Meta-analysis of rare and adverse event data

Measuring the impact of zero-cases studies in evidence synthesis practice using the harms index and benefits index (Hi-Bi)

OBJECTIVES

In evidence synthesis practice, dealing with studies with no cases in both arms has been a tough problem, for which there is no consensus in the research community. In this study, we propose a method to measure the potential impact of studies with no cases for meta-analysis results which we define as harms index (Hi) and benefits index (Bi) as an alternative solution for deciding how to deal with such studies.

METHODS

Hi and Bi are defined by the minimal number of cases added to the treatment arm (Hi) or control arm (Bi) of studies with no cases in a meta-analysis that lead to a change of the direction of the estimates or its statistical significance. Both exact and approximating methods are available to calculate Hi and Bi. We developed the "hibi" module in Stata so that researchers can easily implement the method. A real-world investigation of meta-analyses from Cochrane reviews was employed to evaluate the proposed method.

RESULTS

Based on Hi and Bi, our results suggested that 21.53% (Hi) to 26.55% (Bi) of Cochrane meta-analyses may be potentially impacted by studies with no cases, for which studies with no cases could not be excluded from the synthesis. The approximating method shows excellent specificity (100%) for both Hi and Bi, moderate sensitivity (68.25%) for Bi, and high sensitivity (80.61%) for Hi compared to the exact method.

CONCLUSIONS

The proposed method is practical and useful for systematic reviewers to measure whether studies with no cases impact the results of meta-analyses and may act as an alternative solution for review authors to decide whether to include studies with no events for the synthesis or not.

Reporting Quality of Oral TCM Systematic Reviews Based on the PRISMA Harms Checklist from 2013 to 2020

Background

Systematic reviews focusing on the effectiveness of different kinds of healthcare interventions have been widely published, but there were few guidelines for reporting safety concerns before 2016. The PRISMA harms checklist, which was published in 2016, can standardize reporting quality.

Objectives

To evaluate the safety information reporting quality of oral traditional Chinese medicine (TCM) in systematic reviews before and after the PRISMA harms checklist was published and to explore factors associated with better reporting.

Methods

We searched PubMed, the Cochrane Library, and Embase to identify all systematic reviews using oral TCM as interventions published before (from 2013 to 2015) and after (from 2017 to 2020) the PRISMA harms checklist was published. We used the PRISMA harms checklist to assess the quality of reporting of the safety information to included systematic reviews.

Results

In total, 200 systematic reviews were sampled from eligible studies published between 2013 and 2020. Reviews from 2016 were excluded. Scores on the PRISMA harms checklist (23 items) ranged from 0 to 12. A systematic reviews published after 2016 had better reporting quality compared with studies published before 2016 with regard to the title (P=0.03), results of individual studies (P=0.016), and risk of bias across studies (P=0.043). In all included systematic reviews of our study, the state conclusion in coherence with review findings was reported adequately with the proportion of adherence at 95%; other items had a reporting proportion ranging from 0% to 57%. The four essential reporting items of the PRISMA harms checklist also had a low reporting quality ranging from 0% to 4%.

Conclusions

Oral TCM systematic reviews reported inadequate safety information before and after the PRISMA harms checklist was published. This survey suggested that the PRISMA harms checklist should be recommended more to both original research and systematic review authors.

Bayesian sparse modeling to identify high-risk subgroups in meta-analysis of safety data

Meta-analysis allows researchers to combine evidence from multiple studies, making it a powerful tool for synthesizing information on the safety profiles of new medical interventions. There is a critical need to identify subgroups at high risk of experiencing treatment-related toxicities. However, this remains quite challenging from a statistical perspective as there are a variety of clinical risk factors that may be relevant for different types of adverse events, and adverse events of interest may be rare or incompletely reported. We frame this challenge as a variable selection problem and propose a Bayesian hierarchical model which incorporates a horseshoe prior on the interaction terms to identify high-risk groups. Our proposed model is motivated by a meta-analysis of adverse events in cancer immunotherapy, and our results uncover key factors driving the risk of specific types of treatment-related adverse events.

Different inhaled corticosteroid doses in triple therapy for chronic obstructive pulmonary disease: systematic review and Bayesian network meta-analysis

A systematic review and Bayesian network meta-analysis is necessary to evaluate the efficacy and safety of triple therapy with different doses of inhaled corticosteroids (ICS) in stable chronic obstructive pulmonary disease (COPD). We selected 26 parallel randomized controlled trials (41,366 patients) comparing triple therapy with ICS/long-acting beta-agonist (LABA), LABA/long-acting muscarinic antagonist (LAMA), and LAMA in patients with stable COPD for ≥ 12 weeks from PubMed, EMBASE, the Cochrane Library, and clinical trial registries (search from inception to June 30, 2022). Triple therapy with high dose (HD)-ICS exhibited a lower risk of total exacerbation in pre-specified subgroups treated for ≥ 48 weeks than that with low dose (LD)-ICS (odds ratio [OR] = 0.66, 95% credible interval [CrI] = 0.52–0.94, low certainty of evidence) or medium dose (MD)-ICS (OR = 0.66, 95% CrI = 0.51–0.94, low certainty of evidence). Triple therapy with HD-ICS exhibited a lower risk of moderate-to-severe exacerbation in pre-specified subgroups with forced expiratory volume in 1 s < 65% (OR = 0.6, 95% CrI = 0.37–0.98, low certainty of evidence) or previous exacerbation history (OR = 0.6, 95% CrI = 0.36–0.999, very low certainty of evidence) than triple therapy with MD-ICS. Triple therapy with HD-ICS may reduce acute exacerbation in patients with COPD treated with other drug classes including triple therapy with LD- or MD-ICS or dual therapies.

Benefits and harms of Risperidone and Paliperidone for treatment of patients with schizophrenia or bipolar disorder: a meta-analysis involving individual participant data and clinical study reports

BACKGROUND

Schizophrenia and bipolar disorder are severe mental illnesses which are highly prevalent worldwide. Risperidone and Paliperidone are treatments for either illnesses, but their efficacy compared to other antipsychotics and growing reports of hormonal imbalances continue to raise concerns. As existing evidence on both antipsychotics are solely based on aggregate data, we aimed to assess the benefits and harms of Risperidone and Paliperidone in the treatment of patients with schizophrenia or bipolar disorder, using individual participant data (IPD), clinical study reports (CSRs) and publicly available sources (journal publications and trial registries).

METHODS

We searched MEDLINE, Central, EMBASE and PsycINFO until December 2020 for randomised placebo-controlled trials of Risperidone, Paliperidone or Paliperidone palmitate in patients with schizophrenia or bipolar disorder. We obtained IPD and CSRs from the Yale University Open Data Access project. The primary outcome Positive and Negative Syndrome Scale (PANSS) score was analysed using one-stage IPD meta-analysis. Random-effect meta-analysis of harm outcomes involved methods for coping with rare events. Effect-sizes were compared across all available data sources using the ratio of means or relative risk. We registered our review on PROSPERO, CRD42019140556.

RESULTS

Of the 35 studies, IPD meta-analysis involving 22 (63%) studies showed a significant clinical reduction in the PANSS in patients receiving Risperidone (mean difference - 5.83, 95% CI - 10.79 to - 0.87, I2 = 8.5%, n = 4 studies, 1131 participants), Paliperidone (- 6.01, 95% CI - 8.7 to - 3.32, I2 = 4.3%, n = 13, 3821) and Paliperidone palmitate (- 7.89, 95% CI - 12.1 to - 3.69, I2 = 2.9%, n = 5, 2209). CSRs reported nearly two times more adverse events (4434 vs. 2296 publication, relative difference (RD) = 1.93, 95% CI 1.86 to 2.00) and almost 8 times more serious adverse events (650 vs. 82; RD = 7.93, 95% CI 6.32 to 9.95) than the journal publications. Meta-analyses of individual harms from CSRs revealed a significant increased risk among several outcomes including extrapyramidal disorder, tardive dyskinesia and increased weight. But the ratio of relative risk between the different data sources was not significant. Three treatment-related gynecomastia events occurred, and these were considered mild to moderate in severity.

CONCLUSION

IPD meta-analysis conclude that Risperidone and Paliperidone antipsychotics had a small beneficial effect on reducing PANSS score over 9 weeks, which is more conservative than estimates from reviews based on journal publications. CSRs also contained significantly more data on harms that were unavailable in journal publications or trial registries. Sharing of IPD and CSRs are necessary when performing meta-analysis on the efficacy and safety of antipsychotics.

Geriatrics on beers criteria medications at risk of adverse drug events using real-world data

OBJECTIVES

The established Beers Criteria consider side effects and safety concerns when prescribing drugs to the elderly. As the criteria suggest that attention should be paid toward prescriptions rather than prescription prohibition lists, these Beers Criteria medications (BCMs) are used appropriately under unavoidable circumstances.

METHODS

Patients aged ≥ 65 years and with an experience of being prescribed inappropriate medications at Konyang University Hospital, South Korea, were selected. We analyzed data from the Korea Adverse Event Reporting System (KAERS) and the Food and Drug Administration Adverse Event Reporting System (FAERS) of the United States to identify medication-induced adverse drug events (ADEs). The actual incidence was predicted by multiplying the incidence and number of BCMs prescribed to the patients. The proportional reporting ratio (PRR) and reporting odds ratio (ROR) were calculated using KAERS and FAERS data.

RESULTS

We predicted that the incidence of ADEs would be higher for metoclopramide, chlorpheniramine, and amitriptyline in patients using medications for more than 1 day and metoclopramide, chlorpheniramine, and ketoprofen in patients using medications only for 1 day. Among the ADEs reported to KAERS and FAERS, significant ROR and PRR values were noted for clonazepam (drowsiness), nortriptyline (sleepiness), and zolpidem (amnesia, somnambulism, agitation, dependence, nightmare, and dysgeusia).

CONCLUSION

This study highlighted the actual status of BCM prescriptions in clinical institutions and predicted the incidence of ADEs. We concluded that greater care must be taken while prescribing BCMs to the elderly and indicators, such as PRR and ROR should be monitored regularly.

Relationships of physical activity and sedentary behaviour with the previous and subsequent nights' sleep in children and youth: A systematic review and meta-analysis

The interrelationships between sleep and daytime movement behaviours have been examined at interindividual level. Studies of within-person, temporal relationships of daytime physical activity (PA) and sedentary behaviour with the previous and subsequent nights' sleep are increasing. The present systematic review and meta-analysis synthesised the results of studies in school-aged children and youth. Eight databases (MEDLINE, PsycINFO, EMBASE, Global Health, PubMed, Web of Science, SPORTDiscus, and CINAHL) were searched for peer-reviewed articles that examined the association between daytime movement behaviours (including PA, sedentary time, or sedentary recreational screen time) and night-time sleep on the same day, or the association between night-time sleep and daytime movement behaviours the next day, in children and youth. A total of 11 studies comprising 9,622 children and youth aged 5-15 years met the inclusion criteria. Sedentary time was negatively associated with the subsequent night's sleep duration (r = -0.12, 95% confidence interval -0.23 to -0.00; I²  = 93%; p = .04). Positive relationships between PA and the previous or subsequent night's sleep duration were observed only for studies that adjusted for accelerometer wear time. There was some evidence suggesting that a longer sleep duration was associated with less sedentary time and a higher proportion of the daytime spent being physically active and vice versa, although the association was weak and based on a limited number of studies. From a clinical perspective, promotion of either sleep hygiene or daytime PA should be planned with considerations of the virtuous or vicious circle between these behaviours and monitor concurrent effects on the others.

A comparison of confidence distribution approaches for rare event meta-analysis

Meta-analysis of rare event data has recently received increasing attention due to the challenging issues rare events pose to traditional meta-analytic methods. One specific way to combine information and analyze rare event meta-analysis data utilizes confidence distributions (CDs). While several CD methods exist, no comparisons have been made to determine which method is best suited for homogeneous or heterogeneous meta-analyses with rare events. In this article, we review several CD methods: Fisher's classic P-value combination method, one that combines P-value functions, another that combines confidence intervals, and one that combines confidence log-likelihood functions. We compare these CD approaches, and we propose and compare variations of these methods to determine which method produces reliable results for homogeneous or heterogeneous rare event meta-analyses. We find that for homogeneous rare event data, most CD methods perform very well. On the other hand, for heterogeneous rare event data, there is a clear split in performance between some CD methods, with some performing very poorly and others performing reasonably well.

Janus Kinase Inhibitors and Risk of Venous Thromboembolism: A Systematic Review and Meta-analysis

OBJECTIVE

To assess the risk of venous thromboembolism (VTE) in patients treated with Janus kinase (JAK) inhibitors in clinical trials.

PATIENTS AND METHODS

We performed a literature search of Ovid MEDLINE and ePub Ahead of Print, In-Process & Other Non-Indexed Citations, and Daily; Ovid EMBASE; Ovid Cochrane Central Register of Controlled Trials; Ovid Cochrane Database of Systematic Reviews; and Scopus, from inception to December 4, 2019, for randomized, placebo-controlled trials with JAK inhibitors as an intervention and reported adverse events. Odds ratio with 95% CI was calculated to estimate the VTE risk using a random effects model. Two independent reviewers screened and extracted data. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to assess certainty in estimated VTE risk.

RESULTS

We included 29 trials (13,910 patients). No statistically significant association was found between use of JAK inhibitors and risk of VTE (odds ratio, 0.91; 95% CI, 0.57 to 1.47; P=.70; I²=0; low certainty because of serious imprecision). Results using Bayesian analysis were consistent with those of the primary analysis. Results of stratified and meta-regression analyses suggested no interaction by dose of drug, indication for treatment, or length of follow-up.

CONCLUSION

We found insufficient evidence to support an increased risk of JAK inhibitor-associated VTE based on currently available data.

Applications of simple and accessible methods for meta-analysis involving rare events: A simulation study

Meta-analysis of clinical trials targeting rare events face particular challenges when the data lack adequate number of events and are susceptible to high levels of heterogeneity. The standard meta-analysis methods (DerSimonian Laird (DL) and Mantel–Haenszel (MH)) often lead to serious distortions because of such data sparsity. Applications of the methods suited to specific incidence and heterogeneity characteristics are lacking, thus we compared nine available methods in a simulation study. We generated 360 meta-analysis scenarios where each considered different incidences, sample sizes, between-study variance (heterogeneity) and treatment allocation. We include globally recommended methods such as inverse-variance fixed/random-effect (IV-FE/RE), classical-MH, MH-FE, MH-DL, Peto, Peto-DL and the two extensions for MH bootstrapped-DL (bDL) and Peto-bDL. Performance was assessed on mean bias, mean error, coverage and power. In the absence of heterogeneity, the coverage and power when combined revealed small differences in meta-analysis involving rare and very rare events. The Peto-bDL method performed best, but only in smaller sample sizes involving rare events. For medium-to-larger sample sizes, MH-bDL was preferred. For meta-analysis involving very rare events, Peto-bDL was the best performing method which was sustained across all sample sizes. However, in meta-analysis with 20% or more heterogeneity, the coverage and power were insufficient. Performance based on mean bias and mean error was almost identical across methods. To conclude, in meta-analysis of rare binary outcomes, our results suggest that Peto-bDL is better in both rare and very rare event settings in meta-analysis with limited sample sizes. However, when heterogeneity is large, the coverage and power to detect rare events are insufficient. Whilst this study shows that some of the less studied methods appear to have good properties under sparse data scenarios, further work is needed to assess them against the more complex distributional-based methods to understand their overall performances.

Zero-cell corrections in random-effects meta-analyses

The standard estimator for the log odds ratio (the unconditional maximum likelihood estimator) and the delta-method estimator for its standard error are not defined if the corresponding 2 × 2 table contains at least one "zero cell". This is also an issue when estimating the overall log odds ratio in a meta-analysis. It is well known that correcting for zero cells by adding a small increment should be avoided. Nevertheless, these zero-cell corrections continue to be used. With this Brief Method Note, we want to warn of a particularly bad zero-cell correction. For this, we conduct a simulation study comparing the following two zero-cell corrections under the ordinary random-effects model: (a) adding 1 2 to all cells of all the individual studies' 2 × 2 tables independently of any zero-cell occurrences and (b) adding 1 2 to all cells of only those 2 × 2 tables containing at least one zero cell. The main finding is that correction (a) performs worse than correction (b). Thus, we strongly discourage the use of correction (a).

Systematic review with meta-analysis: comparative risk of lymphoma with anti-tumour necrosis factor agents and/or thiopurines in patients with inflammatory bowel disease

BACKGROUND

The risk of lymphoma in patients with inflammatory bowel disease (IBD) treated with anti-TNF agents remains unclear.

AIM

To assess the comparative risk of lymphoma with anti-TNF agents and/or thiopurines in IBD METHODS: We searched PubMed, EMBASE and Cochrane Library to identify studies that evaluated lymphoproliferative disorders associated with anti-TNF agents with or without thiopurines. The risk of lymphoma was assessed through four comparator groups: combination therapy (anti-TNF plus thiopurine), anti-TNF monotherapy, thiopurine monotherapy and control group. Pooled incidence rate ratios (IRR) were estimated through Poisson-normal models.

RESULTS

Four observational studies comprising 261 689 patients were included. As compared with patients unexposed to anti-TNF and thiopurines, those exposed to anti-TNF monotherapy, thiopurine monotherapy or combination therapy had pooled IRR (per 1000 patient-years) of lymphoma of 1.52 (95% CI: 1.06-2.19; P = 0.023), 2.23 (95% CI: 1.79-2.79; P < 0.001) and 3.71 (95% CI: 2.30-6.00; P ≤ 0.01), respectively. The risk of lymphoma associated with combination therapy was higher than with thiopurines or anti-TNF alone with pooled IRR of 1.70 (95% CI: 1.03-2.81; P = 0.039) and 2.49 (95% CI: 1.39-4.47; P = 0.002), respectively. The risk did not differ between anti-TNF monotherapy and thiopurine monotherapy with pooled IRR of 0.72 (95% CI: 0.48-1.07; P = 0.107). All observational studies were of high quality according to the Newcastle-Ottawa scale.

CONCLUSIONS

There is an increased risk of lymphoma in IBD patients treated with anti-TNF agents, either alone or when combined with thiopurines.

Assessing the quality of meta-analyses in systematic reviews in pharmaceutical research in Iran by 2016: A systematic review

Background: Meta-analyses, like all other studies, may be poorly designed and implemented. This study was designed to determine the quality of meta-analyses in systematic reviews in the field of pharmaceutical research in Iran. Methods: Web of Science Core Collection, EMBASE, Ovid Medline, CINAHL, Scopus, and PubMed were systematically searched on June 4, 2017. The search was limited to the researches in the field of pharmaceutical studies. Based on inclusion criteria, 104 systematic reviews with meta-analysis (SRMA) were selected and assessed using quality assessment tools introduced by Higgins. Results: Participants, experimental interventions, and outcomes were reported in all the articles. Comparator intervention and study design were correctly reported in 103 (99.04%) and 101 (97.12%) articles, respectively. The comprehensive search strategy was available only in 48 articles (46.16%), and there was no evidence of a comprehensive search in 56 articles (53.84%). Risk of bias was investigated in 78 articles (75%). Also, funnel plots were the most commonly used method for reporting the bias in 64 articles (46.42%). Conclusion: In many of the meta-analyses, several items of the tool that represented a high-quality meta-analysis were absent. According to the findings, the comprehensive search and quality assessment were not at an appropriate level. Thus, the importance of reproducibility of information and quality assessment of included studies should be emphasized.

A systematic survey showed important limitations in the methods for assessing drug safety among systematic reviews

OBJECTIVES

This study aimed to examine the design, conduct, and analysis of systematic reviews assessing drug safety through a cross-sectional survey.

STUDY DESIGN AND SETTING

We searched PubMed to identity systematic reviews published in the Cochrane Database of Systematic Reviews and Core Clinical Journals indexed in 2015 and randomly sampled systematic reviews assessing drug effects at a 1:1 ratio of Cochrane and non-Cochrane reviews. Teams of two investigators independently conducted study screening and collected data, using prespecified, standardized questionnaires. In addition to general information, we collected details about the planning and analyses of safety outcomes.

RESULTS

We included 120 systematic reviews, including 60 Cochrane and 60 non-Cochrane reviews. Most reviews searched PubMed/MEDLINE (n = 117, 97.5%), EMBASE (n = 105, 87.5%), and Cochrane CENTRAL (n = 110, 91.7%) and conducted independent and duplicate study selection (n = 98, 81.7%), risk of bias assessment (n = 105, 87.5%), and data collection (n = 105, 87.5%). Only nine (7.5%) reviews clearly defined safety outcomes, and seven (5.8%) defined a primary safety outcome; none stated whether the primary safety outcome was predefined. Among the 80 reviews that pooled the primary dichotomous safety data across studies, less than half (41%, n = 33) conducted subgroup analysis to explore for sources of heterogeneity or reported a GRADE assessment for the overall quality of evidence. Cochrane reviews were more likely to provide a study protocol (100% vs. 23.3%; P < 0.001), involve methodologists (53.3% vs. 20.0%; P < 0.001), and report a GRADE assessment for the primary safety outcome (70.6% vs. 19.6%; P < 0.001).

CONCLUSION

Our findings highlighted areas for improved planning and analysis in the assessment of drug safety among systematic reviews. Cochrane reviews were superior to non-Cochrane reviews; however, most reviews did not prespecify their safety outcomes or methods for analysis, explore sources of heterogeneity among pooled effects, or assess the overall quality of evidence with the GRADE approach.

Exclusion of studies with no events in both arms in meta-analysis impacted the conclusions

OBJECTIVES

Classical meta-analyses routinely treated studies with no events in both arms noninformative and excluded them from analyses. This study assessed whether such studies contain information and have an influence on the conclusions of meta-analyses.

STUDY DESIGN AND SETTING

We collected meta-analyses of binary outcomes with at least one study having no events in both arms from Cochrane systematic reviews (2003-2018). We used the generalized linear mixed model to reanalyze these meta-analyses by two approaches: one including studies with no events in both arms and one excluding such studies. The magnitude and direction of odds ratio (OR), P value, and width of 95% confidence interval (CI) were compared. A simulation study was conducted to examine the robustness of results.

RESULTS

We identified 442 meta-analyses. In comparing paired meta-analyses that included studies with no events in both arms vs. those not, 8 (1.80%) resulted in different directions on OR; 41 (9.28%) altered conclusions on statistical significance. Substantial changes occurred on P value (55.66% increased and 44.12% decreased) and the width of 95% CI (50.68% inflated and 49.32% declined) when excluding studies with no events. Simulation study confirmed these findings.

CONCLUSION

Studies with no events in both arms are not necessarily noninformative. Excluding such studies may alter conclusions.

Improved inference for fixed-effects meta-analysis of 2 × 2 tables

Meta-analysis of 2 × 2 tables is common and useful in research topics including analysis of adverse events and survey research data. Fixed-effects inference typically centers on measures of association such as the Cochran-Mantel-Haenszel statistic or Woolf's estimator, but relies on assuming exact homogeneity across studies, which is often unrealistic. By showing that estimators of several widely-used methods have meaningful estimands even in the presence of heterogeneity, we derive improved confidence intervals for them under heterogeneity. These improvements over current methods are illustrated by simulation, and we also study which factors affect the coverage levels. We find that our confidence intervals provide coverage closer to the nominal level when heterogeneity is present, in both small and large-sample settings. The conventional confidence intervals derived under homogeneity are often conservative, though anti-conservative inferences occur in some scenarios. We also apply the proposed methods to a meta-analysis of 19 randomized clinical trials on the effect of sclerotherapy in preventing first bleeding for patients with cirrhosis and esophagogastric varices. Our methods provide a more interpretable approach to meta-analyzing binary data and more accuracy in characterizing the uncertainty of the estimators.

Comparisons of exacerbations and mortality among regular inhaled therapies for patients with stable chronic obstructive pulmonary disease: Systematic review and Bayesian network meta-analysis

BACKGROUND

Although exacerbation and mortality are the most important clinical outcomes of stable chronic obstructive pulmonary disease (COPD), the drug classes that are the most efficacious in reducing exacerbation and mortality among all possible inhaled drugs have not been determined.

METHODS AND FINDINGS

We performed a systematic review (SR) and Bayesian network meta-analysis (NMA). We searched Medline, EMBASE, the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, the European Union Clinical Trials Register, and the official websites of pharmaceutical companies (from inception to July 9, 2019). The eligibility criteria were as follows: (1) parallel-design randomized controlled trials (RCTs); (2) adults with stable COPD; (3) comparisons among long-acting muscarinic antagonists (LAMAs), long-acting beta-agonists (LABAs), inhaled corticosteroids (ICSs), combined treatment (ICS/LAMA/LABA, LAMA/LABA, or ICS/LABA), or a placebo; and (4) study duration ≥ 12 weeks. This study was prospectively registered in International Prospective Register of Systematic Reviews (PROSPERO; CRD42017069087). In total, 219 trials involving 228,710 patients were included. Compared with placebo, all drug classes significantly reduced the total exacerbations and moderate to severe exacerbations. ICS/LAMA/LABA was the most efficacious treatment for reducing the exacerbation risk (odds ratio [OR] = 0.57; 95% credible interval [CrI] 0.50-0.64; posterior probability of OR > 1 [P(OR > 1)] < 0.001). In addition, in contrast to the other drug classes, ICS/LAMA/LABA and ICS/LABA were associated with a significantly higher probability of reducing mortality than placebo (OR = 0.74, 95% CrI 0.59-0.93, P[OR > 1] = 0.004; and OR = 0.86, 95% CrI 0.76-0.98, P[OR > 1] = 0.015, respectively). The results minimally changed, even in various sensitivity and covariate-adjusted meta-regression analyses. ICS/LAMA/LABA tended to lower the risk of cardiovascular mortality but did not show significant results. ICS/LAMA/LABA increased the probability of pneumonia (OR for triple therapy = 1.56; 95% CrI 1.19-2.03; P[OR > 1] = 1.000). The main limitation is that there were few RCTs including only less symptomatic patients or patients at a low risk.

CONCLUSIONS

These findings suggest that triple therapy can potentially be the best option for stable COPD patients in terms of reducing exacerbation and all-cause mortality.

Prompt closure versus gradual weaning of extraventricular drainage for hydrocephalus in adult patients with aneurysmal subarachnoid haemorrhage: a systematic review protocol with meta-analysis and trial sequential analysis

INTRODUCTION

In Neuro Intensive Care Units (NICU) and neurosurgical units, patients with an external ventricular drain (EVD) due to hydrocephalus following aneurysmal subarachnoid haemorrhage (SAH) are commonly seen. Cessation of the EVD involves the dilemma of either closing the EVD directly, or gradually weaning it before removal. Development of increased intracranial pressure (ICP) and acute hydrocephalus with subsequent need of a permanent shunt has been associated with prompt closure of theEVD, whereas increased risk of infection with possible spreading to the brain and subsequent patient fatality is suspected in connection to a longer treatment as seen in gradual weaning. Sparse data exist on the recommendation of cessation strategy and patients are currently being treated on the basis of personal experience and expert opinion. The objective of this systematic review is to assess the available evidence from clinical trials on the effects of prompt closure versus gradual weaning of EVD treatment for hydrocephalus in adult patients with SAH.

METHODS AND ANALYSIS

We will search for randomised clinical trials in major international databases. Two authors will independently screen and select references for inclusion, extract data and assess the methodological quality of the included randomised clinical trials using the Cochrane risk of bias tool. Any disagreement will be resolved by consensus. We will analyse the extracted data using Review Manager and trial sequential analysis. To assess the quality of the evidence, we will create a 'Summary of Findings' table containing our primary and secondary outcomes using the GRADE assessment.

ETHICS AND DISSEMINATION

Results will be published widely according to the interest of the society. No possible impact, harm or ethical concerns are expected doing this protocol.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42018108801.

Effects of maternal influenza vaccination on adverse birth outcomes: A systematic review and Bayesian meta-analysis

BACKGROUND

Although pregnant women are a priority group for influenza vaccination, its effect on birth outcomes has long been debated. Numerous observational studies and a few randomized controlled studies have been conducted, with inconsistent results.

OBJECTIVES

To evaluate the association of influenza vaccination in pregnancy with adverse birth outcomes.

DATA SOURCE

The Cochrane Library, PubMed, EMBASE, Web of Science, and Scopus were searched.

STUDY ELIGIBILITY CRITERIA

This analysis included randomized placebo-controlled studies, cohort studies, and case-control studies, in which inactivated influenza vaccination was given during pregnancy and fetal adverse birth outcomes were assessed.

PARTICIPANTS & INTERVENTION

Women who received inactivated influenza vaccine during pregnancy and their offspring.

STUDY APPRAISAL AND SYNTHESIS

Two independent reviewers and a third reviewer collaborated in study selection and data extraction. A Bayesian 3-level random-effects model was utilized to assess the impact of maternal influenza vaccination on birth outcomes, which were presented as odds ratios (ORs) with 95% credible interval (CrIs). Bayesian outcome probabilities (P) of an OR<1 were calculated, and values of at least 90% (0.9) were deemed to indicate a significant result.

RESULTS

Among the 6,249 identified publications, 48 studies were eligible for the meta-analysis, including 2 randomized controlled trials, 41 cohort studies, and 5 case-control studies. The risk of none of the following adverse birth outcomes decreased significantly: preterm birth (OR = 0.945, 95% CrI: 0.736-1.345, P = 73.3%), low birth weight (OR = 0.928, 95% CrI: 0.432-2.112, P = 76.7%), small for gestational age (OR = 0.971, 95% CrI: 0.249-4.217,P = 63.3%), congenital malformation (OR = 1.026, 95% CrI: 0.687-1.600, P = 38.0%), and fetal death (OR = 0.942, 95% CrI: 0.560-1.954, P = 61.6%). Summary estimates including only cohort studies showed significantly decreased risks for preterm birth, small for gestational age and fetal death. However, after adjusting for season at the time of vaccination and countries' income level, only fetal death remained significant.

CONCLUSION

This Bayesian meta-analysis did not find a protective effect of maternal influenza vaccination against adverse birth outcomes, as reported in previous studies. In fact, our results showed evidence of null associations between maternal influenza vaccination and adverse birth outcomes.

Real-world Performance of Meta-analysis Methods for Double-Zero-Event Studies with Dichotomous Outcomes Using the Cochrane Database of Systematic Reviews

BACKGROUND

Meta-analysis combines multiple independent studies, which can increase power and provide better estimates. However, it is unclear how best to deal with studies with zero events; such studies are also known as double-zero-event studies (DZS). Several statistical methods have been proposed, but the agreement among different approaches has not been systematically assessed using real-world published systematic reviews.

METHODS

The agreement of five commonly used methods (i.e., the inverse-variance, Mantel-Haenszel, Peto, Bayesian, and exact methods) was assessed using the Cohen's κ coefficients using 368 meta-analyses with rare events selected from the Cochrane Database of Systematic Reviews. Three continuity corrections, including the correction of a constant 0.5, the treatment arm continuity correction (TACC), and the empirical (EMP) correction, were used to handle DZS when applying inverse-variance and Mantel-Haenszel methods.

RESULTS

When the proportion of DZS studies was lower than 50% in a meta-analysis, different methods had moderately high agreement. However, when this proportion was increased to be over 50%, the agreement among the methods decreased to different extents. For the Bayesian, exact, and Peto methods and the inverse-variance and Mantel-Haenszel methods using the EMP correction, their agreement coefficients with the inverse-variance and Mantel-Haenszel methods using a constant 0.5 and TACC decreased from larger than 0.70 to smaller than 0.30. In contrast, the agreement coefficients only decreased slightly among the Bayesian, exact, and Peto methods and the inverse-variance and Mantel-Haenszel methods using the EMP correction.

CONCLUSIONS

To utilize all available information and reduce research waste and avoid overestimating the effect, meta-analysts should incorporate DZS, rather than simply removing them. The Peto and other conventional methods with continuity correction should be avoided when the proportion of DZS is extremely high. The exact and Bayesian methods are highly recommended, except when none of the included studies have an event in one or both treatment arms.

Adverse side effects of dexamethasone in surgical patients

BACKGROUND

In the perioperative period, dexamethasone is widely and effectively used for prophylaxis of postoperative nausea and vomiting (PONV), for pain management, and to facilitate early discharge after ambulatory surgery.Long-term treatment with steroids has many side effects, such as adrenal insufficiency, increased infection risk, hyperglycaemia, high blood pressure, osteoporosis, and development of diabetes mellitus. However, whether a single steroid load during surgery has negative effects during the postoperative period has not yet been studied.

OBJECTIVES

To assess the effects of a steroid load of dexamethasone on postoperative systemic or wound infection, delayed wound healing, and blood glucose change in adult surgical patients (with planned subgroup analysis of patients with and without diabetes).

SEARCH METHODS

We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library, and the Web of Science for relevant articles on 29 January 2018. We searched without language or date restriction two clinical trial registries to identify ongoing studies, and we handsearched the reference lists of relevant publications to identify all eligible trials.

SELECTION CRITERIA

We searched for randomized controlled trials comparing an incidental steroid load of dexamethasone versus a control intervention for adult patients undergoing surgery. We required that studies include a follow-up of 30 days for proper assessment of the number of postoperative infections, delayed wound healing, and the glycaemic response.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for eligibility, extracted data from relevant studies, and assessed all included studies for bias. We resolved differences by discussion and pooled included studies in a meta-analysis. We calculated Peto odds ratios (ORs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes. Our primary outcomes were postoperative systemic or wound infection, delayed wound healing, and glycaemic response within 24 hours. We created a funnel plot for the primary outcome postoperative (wound or systemic) infection. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included in the meta-analysis 37 studies that included adults undergoing a large variety of surgical procedures (i.e. abdominal surgery, cardiac surgery, neurosurgery, and orthopaedic surgery). We excluded one previously included study, as this study was recently retracted. Age range of participants was 18 to 80 years. There is probably little or no difference in the risk of postoperative (wound or systemic) infection with dexamethasone compared with no treatment, placebo, or active control (ramosetron, ondansetron, or tropisetron) (Peto OR 1.01, 95% confidence interval (CI) 0.80 to 1.27; 4603 participants, 26 studies; I² = 32%; moderate-quality evidence). The effects of dexamethasone on delayed wound healing are unclear because the wide confidence interval includes both meaningful benefit and harm (Peto OR 0.99, 95% CI 0.28 to 3.43; 1072 participants, eight studies; I² = 0%; low-quality evidence). Dexamethasone may produce a mild increase in glucose levels among participants without diabetes during the first 12 hours after surgery (MD 13 mg/dL, 95% CI 6 to 21; 10 studies; 595 participants; I² = 50%; low-quality evidence). We identified two studies reporting on glycaemic response after dexamethasone in participants with diabetes within 24 hours after surgery (MD 32 mg/dL, 95% CI 15 to 49; 74 participants; I² = 0%; very low-quality evidence).

AUTHORS' CONCLUSIONS

A single dose of dexamethasone probably does not increase the risk for postoperative infection. It is uncertain whether dexamethasone has an effect on delayed wound healing in the general surgical population owing to imprecision in trial results. Participants with increased risk for delayed wound healing (e.g. participants with diabetes, those taking immunosuppressive drugs) were not included in the randomized studies reporting on delayed wound healing included in this meta-analysis; therefore our findings should be extrapolated to the clinical setting with caution. Furthermore, one has to keep in mind that dexamethasone induces a mild increase in glucose. For patients with diabetes, very limited evidence suggests a more pronounced increase in glucose. Whether this influences wound healing in a clinically relevant way remains to be established. Once assessed, the two studies awaiting classification and three that are ongoing may alter the conclusions of this review.

Comparison of universal prophylaxis and preemptive approach for cytomegalovirus associated outcome measures in renal transplant patients: A meta-analysis of available data

Cytomegalovirus (CMV) is a ubiquitous latent human virus that often causes complications in renal transplantation recipients. Universal prophylaxis and preemptive therapy are alternative strategies to prevent CMV associated complications. This meta-analysis aimed to assess available data comparing the effectiveness of prophylaxis and preemptive therapy for preventing adverse outcomes. We searched the PubMed, Ovid, Web of Science, Cochrane Library, and Open Grey databases using a combination of keywords. Random effects models along with the Paule-Mandel estimator were used to synthesize pooled effect estimates. Eleven studies were eligible for the final analysis. Universal prophylaxis was better at preventing CMV disease than the preemptive approach (risk difference = -0.0459; confidence intervals = -0.0791, -0.0127; P-value = 0.0067; number needed to treat [NNT] = 22 [1/0.0459]; high, 79 [1/0.0127] patients; low, 13 [1/0.0791] patients). Subgroup analysis revealed a more consistent effect among studies published after 2010, with negligible between-study heterogeneity. The NNT for universal prophylaxis to prevent one excess CMV disease concerning preemptive therapy was 16 (1/0.0630) patients (high, 25 [1/0.0394]; low, 12 [1/0.0867] patients) in the subgroup of studies performed after 2010. We detected no significant difference between the two strategies regarding acute rejection and graft loss, with negligible variability due to heterogeneity between studies. Although universal prophylaxis performed better than the preemptive strategy for the prevention of CMV disease, the high NNT value may discourage the use of CMV prophylaxis. Since there were no differences between the strategies concerning acute rejection and graft loss, this study supports the use of the preemptive approach as an alternative to universal prophylaxis.

The reporting of safety among drug systematic reviews was poor before the implementation of the PRISMA harms checklist

OBJECTIVES

To examine, through a cross-sectional survey, how well safety information was reported among drug systematic reviews predating PRISMA harms checklist and explore factors associated with better reporting.

STUDY DESIGN AND SETTING

We searched PubMed to identify all systematic reviews published in the Cochrane Database of Systematic Review or the core clinical journals in 2015, one year before the PRISMA harms checklist was published. We randomly selected, in a 1:1 ratio, Cochrane and non-Cochrane systematic reviews assessing drug effects (including both efficacy and safety). We used the PRISMA harms checklist published in 2016 to assess the quality of reporting of drug safety information. Multivariable linear regression analyses were used to explore the association of six prespecified variables with more complete reporting of PRISMA harms items.

RESULTS

We included 120 systematic reviews, including 60 Cochrane and 60 non-Cochrane reviews. Scores on the PRISMA harms checklist (23 items) were low (median 4, [first, third quartile: 2, 6]), with no difference between Cochrane and non-Cochrane reviews (4.5 [2, 7] vs. 4 [2.5, 5]; P = 0.29). Among all eligible reviews, only one item (i.e., state conclusions in coherence with the review findings) was reported adequately (proportion of adherence 81.6%); proportion of reporting for other items ranged from 1.7% to 68.3%. The four essential reporting items from PRISMA harms checklist were also poorly complied (proportion of adherence ranged from 1.7% to 9.2%). Multivariable linear regression analyses found no significant associations between any study characteristic and reporting on the PRISMA harms, likely because of limited variability in scores across studies.

CONCLUSIONS

The reporting of safety information was poor both for Cochrane and non-Cochrane drug systematic reviews predating PRISMA harms checklist. The findings suggested a strong need to use the PRISMA harms checklist for reporting safety among drug systematic reviews.

Comparing Long-term Mortality After Carotid Endarterectomy vs Carotid Stenting Using a Novel Instrumental Variable Method for Risk Adjustment in Observational Time-to-Event Data

IMPORTANCE

Choosing between competing treatment options is difficult for patients and clinicians when results from randomized and observational studies are discordant. Observational real-world studies yield more generalizable evidence for decision making than randomized clinical trials, but unmeasured confounding, especially in time-to-event analyses, can limit validity.

OBJECTIVES

To compare long-term survival after carotid endarterectomy (CEA) and carotid artery stenting (CAS) in real-world practice using a novel instrumental variable method designed for time-to-event outcomes, and to compare the results with traditional risk-adjustment models used in observational research for survival analyses.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter cohort study was performed. The Vascular Quality Initiative, an observational quality improvement registry, was used to compare long-term mortality after CEA vs CAS. The study included 86 017 patients who underwent CEA (n = 73 312) or CAS (n = 12 705) between January 1, 2003, and December 31, 2016. Patients were followed up for long-term mortality assessment by linking the registry data to Medicare claims. Medicare claims data were available through September 31, 2015.

EXPOSURE

Procedure type (CEA vs CAS).

MAIN OUTCOMES AND MEASURES

The hazard ratios (HRs) of all-cause mortality using unadjusted, adjusted, propensity-matched, and instrumental variable methods were examined. The instrumental variable was the proportion of CEA among the total carotid procedures (endarterectomy and stenting) performed at each hospital in the 12 months before each patient's index operation and therefore varies over the study period.

RESULTS

Participants who underwent CEA had a mean (SD) age of 70.3 (9.4) years compared with 69.1 (10.4) years for CAS, and most were men (44 191 [60.4%] for CEA and 8117 [63.9%] for CAS). The observed 5-year mortality was 12.8% (95% CI, 12.5%-13.2%) for CEA and 17.0% (95% CI, 16.0%-18.1%) for CAS. The unadjusted HR of mortality for CEA vs CAS was 0.67 (95% CI, 0.64-0.71), and Cox-adjusted and propensity-matched HRs were similar (0.69; 95% CI, 0.65-0.74 and 0.71; 95% CI, 0.65-0.77, respectively). These findings are comparable with published observational studies of CEA vs CAS. However, the association between CEA and mortality was more modest when estimated by instrumental variable analysis (HR, 0.83; 95% CI, 0.70-0.98), a finding similar to data reported in randomized clinical trials.

CONCLUSIONS AND RELEVANCE

The study found a survival advantage associated with CEA over CAS in unadjusted and Cox-adjusted analyses. However, this finding was more modest when using an instrumental variable method designed for time-to-event outcomes for risk adjustment. The instrumental variable-based results were more similar to findings from randomized clinical trials, suggesting this method may provide less biased estimates of time-dependent outcomes in observational analyses.

Adverse side effects of dexamethasone in surgical patients

BACKGROUND

In the perioperative period, dexamethasone is widely and effectively used for prophylaxis of postoperative nausea and vomiting (PONV), for pain management, and to facilitate early discharge after ambulatory surgery.Long-term treatment with steroids has many side effects, such as adrenal insufficiency, increased infection risk, hyperglycaemia, high blood pressure, osteoporosis, and development of diabetes mellitus. However, whether a single steroid load during surgery has negative effects during the postoperative period has not yet been studied.

OBJECTIVES

To assess the effects of a steroid load of dexamethasone on postoperative systemic or wound infection, delayed wound healing, and blood glucose change in adult surgical patients (with planned subgroup analysis of patients with and without diabetes).

SEARCH METHODS

We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library, and the Web of Science for relevant articles on 29 January 2018. We searched without language or date restriction two clinical trial registries to identify ongoing studies, and we handsearched the reference lists of relevant publications to identify all eligible trials.

SELECTION CRITERIA

We searched for randomized controlled trials comparing an incidental steroid load of dexamethasone versus a control intervention for adult patients undergoing surgery. We required that studies include a follow-up of 30 days for proper assessment of the number of postoperative infections, delayed wound healing, and the glycaemic response.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for eligibility, extracted data from relevant studies, and assessed all included studies for bias. We resolved differences by discussion and pooled included studies in a meta-analysis. We calculated Peto odds ratios (ORs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes. Our primary outcomes were postoperative systemic or wound infection, delayed wound healing, and glycaemic response within 24 hours. We created a funnel plot for the primary outcome postoperative (wound or systemic) infection. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included in the meta-analysis 38 studies that included adults undergoing a large variety of surgical procedures (i.e. abdominal surgery, cardiac surgery, neurosurgery, and orthopaedic surgery). Age range of participants was 18 to 80 years. There is probably little or no difference in the risk of postoperative (wound or systemic) infection with dexamethasone compared with no treatment, placebo, or active control (ramosetron, ondansetron, or tropisetron) (Peto OR 1.01, 95% confidence interval (CI) 0.80 to 1.27; 4931 participants, 27 studies; I² = 27%; moderate-quality evidence). The effects of dexamethasone on delayed wound healing are unclear because the wide confidence interval includes both meaningful benefit and harm (Peto OR 0.99, 95% CI 0.28 to 3.43; 1072 participants, eight studies; I² = 0%; low-quality evidence). Dexamethasone may produce a mild increase in glucose levels among participants without diabetes during the first 12 hours after surgery (MD 13 mg/dL, 95% CI 6 to 21; 10 studies; 595 participants; I² = 50%; low-quality evidence). We identified two studies reporting on glycaemic response after dexamethasone in participants with diabetes within 24 hours after surgery (MD 32 mg/dL, 95% CI 15 to 49; 74 participants; I² = 0%; very low-quality evidence).

AUTHORS' CONCLUSIONS

A single dose of dexamethasone probably does not increase the risk for postoperative infection. It is uncertain whether dexamethasone has an effect on delayed wound healing in the general surgical population owing to imprecision in trial results. Participants with increased risk for delayed wound healing (e.g. participants with diabetes, those taking immunosuppressive drugs) were not included in the randomized studies reporting on delayed wound healing included in this meta-analysis; therefore our findings should be extrapolated to the clinical setting with caution. Furthermore, one has to keep in mind that dexamethasone induces a mild increase in glucose. For patients with diabetes, very limited evidence suggests a more pronounced increase in glucose. Whether this influences wound healing in a clinically relevant way remains to be established. Once assessed, the three studies awaiting classification and two that are ongoing may alter the conclusions of this review.

Methods to systematically review and meta-analyse observational studies: a systematic scoping review of recommendations

Background

Systematic reviews and meta-analyses of observational studies are frequently performed, but no widely accepted guidance is available at present. We performed a systematic scoping review of published methodological recommendations on how to systematically review and meta-analyse observational studies.

Methods

We searched online databases and websites and contacted experts in the field to locate potentially eligible articles. We included articles that provided any type of recommendation on how to conduct systematic reviews and meta-analyses of observational studies. We extracted and summarised recommendations on pre-defined key items: protocol development, research question, search strategy, study eligibility, data extraction, dealing with different study designs, risk of bias assessment, publication bias, heterogeneity, statistical analysis. We summarised recommendations by key item, identifying areas of agreement and disagreement as well as areas where recommendations were missing or scarce.

Results

The searches identified 2461 articles of which 93 were eligible. Many recommendations for reviews and meta-analyses of observational studies were transferred from guidance developed for reviews and meta-analyses of RCTs. Although there was substantial agreement in some methodological areas there was also considerable disagreement on how evidence synthesis of observational studies should be conducted. Conflicting recommendations were seen on topics such as the inclusion of different study designs in systematic reviews and meta-analyses, the use of quality scales to assess the risk of bias, and the choice of model (e.g. fixed vs. random effects) for meta-analysis.

Conclusion

There is a need for sound methodological guidance on how to conduct systematic reviews and meta-analyses of observational studies, which critically considers areas in which there are conflicting recommendations.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0495-9) contains supplementary material, which is available to authorized users.

SGLT-2 inhibitors and the risk of infections: a systematic review and meta-analysis of randomized controlled trials

AIMS

There is concern about the infection-related safety profile of sodium-glucose co-transporter 2 (SGLT-2) inhibitors. We aimed to determine the effect of SGLT-2 inhibitors on genitourinary and other infections via systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

We conducted a systematic search of Medline, EMBASE, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov to identify double-blinded RCTs enrolling ≥ 50 patients with type 2 diabetes which compared an SGLT-2 inhibitor to placebo or active comparator. Two independent reviewers extracted data and appraised study quality. Data were pooled using random-effects models.

RESULTS

Eighty-six RCTs enrolling 50,880 patients were included. SGLT-2 inhibitors increased the risk of genital infections compared to placebo (relative risk [RR] 3.37, 95% CI 2.89-3.93, I² 0%) and active comparator (RR 3.89, 95% CI 3.14-4.82, I² 0.3%). The risk of urinary tract infection (UTI) was not increased with SGLT-2 inhibitors compared to placebo (RR 1.03, 95% CI 0.96-1.11, I² 0%) or active comparator (RR 1.08, 95% CI 0.93-1.25, I² 22%). In drug-specific analyses, only dapagliflozin 10 mg daily was associated with a significantly increased risk of UTI compared to placebo (RR 1.33, 95% CI 1.10-1.61, I² 0%). SGLT-2 inhibitors were associated with a reduced risk of gastroenteritis (RR 0.38, 95% CI 0.20-0.72, I² 0%) but did not affect the risk of respiratory tract infections.

CONCLUSIONS/INTERPRETATION

SGLT-2 inhibitors are associated with an increased risk of genital tract infections. Although there is no association overall between SGLT-2 inhibitors and UTI, higher doses of dapagliflozin are associated with an increased risk.

Early major complications after bariatric surgery in the USA, 2003-2014: a systematic review and meta-analysis

The effectiveness of bariatric surgery has been well-studied. However, complications after bariatric surgery have been understudied. This review assesses <30-d major complications associated with bariatric procedures, including anastomotic leak, myocardial infarction and pulmonary embolism. This review included 71 studies conducted in the USA between 2003 and 2014 and 107,874 patients undergoing either gastric bypass, adjustable gastric banding or sleeve gastrectomy, with mean age of 44 years and pre-surgery body mass index of 46.5 kg m^-2 . Less than 30-d anastomotic leak rate was 1.15%; myocardial infarction rate was 0.37%; pulmonary embolism rate was 1.17%. Among all patients, mortality rate following anastomotic leak, myocardial infarction and pulmonary embolism was 0.12%, 0.37% and 0.18%, respectively. Among surgical procedures, <30-d after surgery, sleeve gastrectomy (1.21% [95% confidence interval, 0.23-2.19%]) had higher anastomotic leak rate than gastric bypass (1.14% [95% confidence interval, 0.84-1.43%]); gastric bypass had higher rates of myocardial infarction and pulmonary embolism than adjustable gastric banding or sleeve gastrectomy. During the review, we found that the quality of complication reporting is lower than the reporting of other outcomes. In summary, <30-d rates of the three major complications after either one of the procedures range from 0% to 1.55%. Mortality following these complications ranges from 0% to 0.64%. Future studies reporting complications after bariatric surgery should improve their reporting quality.

Evidence Synthesis in Harm Assessment of Medicines Using the Example of Rosiglitazone and Myocardial Infarction

The current system of harm assessment of medicines has been criticized for relying on intuitive expert judgment. There is a call for more quantitative approaches and transparency in decision-making. Illustrated with the case of cardiovascular safety concerns for rosiglitazone, we aimed to explore a structured procedure for the collection, quality assessment, and statistical modeling of safety data from observational and randomized studies. We distinguished five stages in the synthesis process. In Stage I, the general research question, population and outcome, and general inclusion and exclusion criteria are defined and a systematic search is performed. Stage II focusses on the identification of sub-questions examined in the included studies and the classification of the studies into the different categories of sub-questions. In Stage III, the quality of the identified studies is assessed. Coding and data extraction are performed in Stage IV. Finally, meta-analyses on the study results per sub-question are performed in Stage V. A Pubmed search identified 30 randomized and 14 observational studies meeting our search criteria. From these studies, we identified 4 higher level sub-questions and 4 lower level sub-questions. We were able to categorize 29 individual treatment comparisons into one or more of the sub-question categories, and selected study duration as an important covariate. We extracted covariate, outcome, and sample size information at the treatment arm level of the studies. We extracted absolute numbers of myocardial infarctions from the randomized study, and adjusted risk estimates with 95% confidence intervals from the observational studies. Overall, few events were observed in the randomized studies that were frequently of relatively short duration. The large observational studies provided more information since these were often of longer duration. A Bayesian random effects meta-analysis on these data showed no significant increase in risk of rosiglitazone for any of the sub-questions. The proposed procedure can be of additional value for drug safety assessment because it provides a stepwise approach that guides the decision-making in increasing process transparency. The procedure allows for the inclusion of results from both randomized an observational studies, which is especially relevant for this type of research.

Short- and long-term mortality after bariatric surgery: A systematic review and meta-analysis

AIMS

The objective of this study was to investigate short- (≤ 30 days) and long-term (≥ 2 years) all-cause mortality after bariatric surgery among adult patients with obesity.

MATERIALS AND METHODS

For short-term mortality, eligible studies comprised randomized controlled trials (RCTs) reporting perioperative mortality. For long-term mortality, eligible studies comprised RCTs and observational studies comparing mortality between obese patients after bariatric surgery and non-operated controls. Random-effects models using a Bayesian or frequentist approach were used to pool effect estimates of short- and long-term mortality, respectively.

RESULTS

Short-term all-cause mortality based on 38 RCTs involving 4030 patients was 0.18% (95% CI, 0.04%-0.38%) and was higher for open surgeries (0.31%; 95% CI, 0.03%-0.97%) and similar in mixed surgeries (0.17%; 95% CI, 0.03%-0.43%) and restrictive surgeries (0.17%; 95% CI, 0.03%-0.45%). For long-term mortality, 12 observational studies involving 27 258 operated patients and 97 154 non-operated obese controls were included. Of these, 8 studies were eligible for the meta-analysis, which showed a reduction of 41% in all-cause mortality (hazard ratio, 0.59; 95% CI, 0.52-0.67; P < .001). Additionally, operated patients were 0.42 times as likely (95% CI, 0.25-0.72, P < .001) and 0.47 times as likely (95% CI, 0.36-0.63, P < .001) as non-operated obese controls to die from cardiovascular diseases and cancer, respectively.

CONCLUSIONS

Bariatric surgery is associated with low short-term mortality and may be associated with long-term reductions in all-cause, cardiovascular and cancer-related mortality.

Avoidance versus use of neuromuscular blocking agents for improving conditions during tracheal intubation or direct laryngoscopy in adults and adolescents

BACKGROUND

Tracheal intubation during induction of general anaesthesia is a vital procedure performed to secure a patient's airway. Several studies have identified difficult tracheal intubation (DTI) or failed tracheal intubation as one of the major contributors to anaesthesia-related mortality and morbidity. Use of neuromuscular blocking agents (NMBA) to facilitate tracheal intubation is a widely accepted practice. However, because of adverse effects, NMBA may be undesirable. Cohort studies have indicated that avoiding NMBA is an independent risk factor for difficult and failed tracheal intubation. However, no systematic review of randomized trials has evaluated conditions for tracheal intubation, possible adverse effects, and postoperative discomfort.

OBJECTIVES

To evaluate the effects of avoiding neuromuscular blocking agents (NMBA) versus using NMBA on difficult tracheal intubation (DTI) for adults and adolescents allocated to tracheal intubation with direct laryngoscopy. To look at various outcomes, conduct subgroup and sensitivity analyses, examine the role of bias, and apply trial sequential analysis (TSA) to examine the level of available evidence for this intervention.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, BIOSIS, International Web of Science, LILACS, advanced Google, CINAHL, and the following trial registries: Current Controlled Trials; ClinicalTrials.gov; and www.centerwatch.com, up to January 2017. We checked the reference lists of included trials and reviews to look for unidentified trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared the effects of avoiding versus using NMBA in participants 14 years of age or older.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We conducted random-effects and fixed-effect meta-analyses and calculated risk ratios (RRs) and their 95% confidence intervals (CIs). We used published data and data obtained by contacting trial authors. To minimize the risk of systematic error, we assessed the risk of bias of included trials. To reduce the risk of random errors caused by sparse data and repetitive updating of cumulative meta-analyses, we applied TSA.

MAIN RESULTS

We identified 34 RCTs with 3565 participants that met our inclusion criteria. All trials reported on conditions for tracheal intubation; seven trials with 846 participants described 'events of upper airway discomfort or injury', and 13 trials with 1308 participants reported on direct laryngoscopy. All trials used a parallel design. We identified 18 dose-finding studies that included more interventions or control groups or both. All trials except three included only American Society of Anesthesiologists (ASA) class I and II participants, 25 trials excluded participants with anticipated DTI, and obesity or overweight was an excluding factor in 13 studies. Eighteen trials used suxamethonium, and 18 trials used non-depolarizing NMBA.Trials with an overall low risk of bias reported significantly increased risk of DTI with no use of NMBA (random-effects model) (RR 13.27, 95% CI 8.19 to 21.49; P < 0.00001; 508 participants; four trials; number needed to treat for an additional harmful outcome (NNTH) = 1.9, I² = 0%, D² = 0%, GRADE = moderate). The TSA-adjusted CI for the RR was 1.85 to 95.04. Inclusion of all trials resulted in confirmation of results and of significantly increased risk of DTI when an NMBA was avoided (random-effects model) (RR 5.00, 95% CI 3.49 to 7.15; P < 0.00001; 3565 participants; 34 trials; NNTH = 6.3, I² = 70%, D² = 82%, GRADE = low). Again the cumulative z-curve crossed the TSA monitoring boundary, demonstrating harmful effects of avoiding NMBA on the proportion of DTI with minimal risk of random error. We categorized only one trial reporting on upper airway discomfort or injury as having overall low risk of bias. Inclusion of all trials revealed significant risk of upper airway discomfort or injury when an NMBA was avoided (random-effects model) (RR 1.37, 95% CI 1.09 to 1.74; P = 0.008; 846 participants; seven trials; NNTH = 9.1, I² = 13%, GRADE = moderate). The TSA-adjusted CI for the RR was 1.00 to 1.85. None of these trials reported mortality. In terms of our secondary outcome 'difficult laryngoscopy', we categorized only one trial as having overall low risk of bias. All trials avoiding NMBA were significantly associated with difficult laryngoscopy (random-effects model) (RR 2.54, 95% CI 1.53 to 4.21; P = 0.0003; 1308 participants; 13 trials; NNTH = 25.6, I² = 0%, D²= 0%, GRADE = low); however, TSA showed that only 6% of the information size required to detect or reject a 20% relative risk reduction (RRR) was accrued, and the trial sequential monitoring boundary was not crossed.

AUTHORS' CONCLUSIONS

This review supports that use of an NMBA may create the best conditions for tracheal intubation and may reduce the risk of upper airway discomfort or injury following tracheal intubation. Study results were characterized by indirectness, heterogeneity, and high or uncertain risk of bias concerning our primary outcome describing difficult tracheal intubation. Therefore, we categorized the GRADE classification of quality of evidence as moderate to low. In light of defined outcomes of individual included trials, our primary outcomes may not reflect a situation that many clinicians consider to be an actual difficult tracheal intubation by which the patient's life or health may be threatened.

An appraisal of meta-analysis guidelines: how do they relate to safety outcomes?

Although well developed to assess efficacy questions, meta-analyses and, more generally, systematic reviews, have received less attention in application to safety-related questions. As a result, many open questions remain on how best to apply meta-analyses in the safety setting. This appraisal attempts to: (i) summarize the current guidelines for assessing individual studies, systematic reviews, and network meta-analyses; (ii) describe several publications on safety meta-analytic approaches; and (iii) present some of the questions and issues that arise with safety data. A number of gaps in the current quality guidelines are identified along with issues to consider when performing a safety meta-analysis. While some work is ongoing to provide guidance to improve the quality of safety meta-analyses, this review emphasizes the critical need for better reporting and increased transparency regarding safety data in the systematic review guidelines. Copyright © 2016 John Wiley & Sons, Ltd.

Thromboelastography (TEG) or thromboelastometry (ROTEM) to monitor haemostatic treatment versus usual care in adults or children with bleeding

BACKGROUND

Severe bleeding and coagulopathy are serious clinical conditions that are associated with high mortality. Thromboelastography (TEG) and thromboelastometry (ROTEM) are increasingly used to guide transfusion strategy but their roles remain disputed. This review was first published in 2011 and updated in January 2016.

OBJECTIVES

We assessed the benefits and harms of thromboelastography (TEG)-guided or thromboelastometry (ROTEM)-guided transfusion in adults and children with bleeding. We looked at various outcomes, such as overall mortality and bleeding events, conducted subgroup and sensitivity analyses, examined the role of bias, and applied trial sequential analyses (TSAs) to examine the amount of evidence gathered so far.

SEARCH METHODS

In this updated review we identified randomized controlled trials (RCTs) from the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1); MEDLINE; Embase; Science Citation Index Expanded; International Web of Science; CINAHL; LILACS; and the Chinese Biomedical Literature Database (up to 5 January 2016). We contacted trial authors, authors of previous reviews, and manufacturers in the field. The original search was run in October 2010.

SELECTION CRITERIA

We included all RCTs, irrespective of blinding or language, that compared transfusion guided by TEG or ROTEM to transfusion guided by clinical judgement, guided by standard laboratory tests, or a combination. We also included interventional algorithms including both TEG or ROTEM in combination with standard laboratory tests or other devices. The primary analysis included trials on TEG or ROTEM versus any comparator.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data; we resolved any disagreements by discussion. We presented pooled estimates of the intervention effects on dichotomous outcomes as risk ratio (RR) with 95% confidence intervals (CIs). Due to skewed data, meta-analysis was not provided for continuous outcome data. Our primary outcome measure was all-cause mortality. We performed subgroup and sensitivity analyses to assess the effect based on the presence of coagulopathy of a TEG- or ROTEM-guided algorithm, and in adults and children on various clinical and physiological outcomes. We assessed the risk of bias through assessment of trial methodological components and the risk of random error through TSA.

MAIN RESULTS

We included eight new studies (617 participants) in this updated review. In total we included 17 studies (1493 participants). A total of 15 trials provided data for the meta-analyses. We judged only two trials as low risk of bias. The majority of studies included participants undergoing cardiac surgery.We found six ongoing trials but were unable to retrieve any data from them. Compared with transfusion guided by any method, TEG or ROTEM seemed to reduce overall mortality (7.4% versus 3.9%; risk ratio (RR) 0.52, 95% CI 0.28 to 0.95; I(2) = 0%, 8 studies, 717 participants, low quality of evidence) but only eight trials provided data on mortality, and two were zero event trials. Our analyses demonstrated a statistically significant effect of TEG or ROTEM compared to any comparison on the proportion of participants transfused with pooled red blood cells (PRBCs) (RR 0.86, 95% CI 0.79 to 0.94; I(2) = 0%, 10 studies, 832 participants, low quality of evidence), fresh frozen plasma (FFP) (RR 0.57, 95% CI 0.33 to 0.96; I(2) = 86%, 8 studies, 761 participants, low quality of evidence), platelets (RR 0.73, 95% CI 0.60 to 0.88; I(2) = 0%, 10 studies, 832 participants, low quality of evidence), and overall haemostatic transfusion with FFP or platelets (low quality of evidence). Meta-analyses also showed fewer participants with dialysis-dependent renal failure.We found no difference in the proportion needing surgical reinterventions (RR 0.75, 95% CI 0.50 to 1.10; I(2) = 0%, 9 studies, 887 participants, low quality of evidence) and excessive bleeding events or massive transfusion (RR 0.38, 95% CI 0.38 to 1.77; I(2) = 34%, 2 studies, 280 participants, low quality of evidence). The planned subgroup analyses failed to show any significant differences.We graded the quality of evidence as low based on the high risk of bias in the studies, large heterogeneity, low number of events, imprecision, and indirectness. TSA indicates that only 54% of required information size has been reached so far in regards to mortality, while there may be evidence of benefit for transfusion outcomes. Overall, evaluated outcomes were consistent with a benefit in favour of a TEG- or ROTEM-guided transfusion in bleeding patients.

AUTHORS' CONCLUSIONS

There is growing evidence that application of TEG- or ROTEM-guided transfusion strategies may reduce the need for blood products, and improve morbidity in patients with bleeding. However, these results are primarily based on trials of elective cardiac surgery involving cardiopulmonary bypass, and the level of evidence remains low. Further evaluation of TEG- or ROTEM-guided transfusion in acute settings and other patient categories in low risk of bias studies is needed.

Pirfenidone, nintedanib and N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis: A systematic review and meta-analysis

BACKGROUND

The prevalence of idiopathic pulmonary fibrosis (IPF) is increasing every year. Pirfenidone and nintedanib were approved for treatment of IPF in 2014, but they received only a conditional recommendation for use and, thus, to date no drugs are strongly recommended for IPF. The aim of this study was to assess the effectiveness and safety of the currently approved drugs for IPF and N-acetylcysteine (NAC), the most debated drug in the last update of guidelines for IPF treatment.

METHODS

RCTs in IPF were identified searching from databases of published and unpublished studies. The influence of pirfenidone, nintedanib and NAC on clinical outcomes, safety, and mortality was assessed via pair-wise meta-analysis.

RESULTS

Ten papers (3847 IPF patients; 2254 treated; 1593 placebo) were included in this study. Our results showed that both pirfenidone and nintedanib, but not NAC, were significantly effective in reducing FVC decline and the risk of FVC ≥10% decline in percent predicted over 12 months. Nintenadib significantly protected against the risk of acute exacerbation and mortality. Pirfenidone and nintedanib showed a similar and good safety profile, whereas NAC provided a signal for increased adverse events.

CONCLUSIONS

The rank of effectiveness emerging from this meta-analysis represents an indirect indicator of potential differences between currently approved doses of pirfenidone and nintedanib. Direct comparisons are necessary to assess this matter, and well designed bench-to-bedside studies would permit to understand the potential of combined, sequential, or adjunctive treatment regimens in which perhaps NAC may have a role for specific clusters of IPF patients.

Central venous catheter (CVC) removal for patients of all ages with candidaemia

BACKGROUND

Candida bloodstream infections most often affect those already suffering serious, potentially life-threatening conditions and often cause significant morbidity and mortality. Most affected persons have a central venous catheter (CVC) in place. The best CVC management in these cases has been widely debated in recent years, while the incidence of candidaemia has markedly increased.

OBJECTIVES

The main purpose of this review is to examine the impact of removing versus retaining a CVC on mortality in adults and children with candidaemia who have a CVC in place.

SEARCH METHODS

We searched the following databases from inception to 3 December 2015: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), EMBASE (Ovid SP), the Commonwealth Agricultural Bureau (CAB), Web of Science and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We searched for missed, unreported and ongoing trials in trial registries and in reference lists of excluded articles.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) and quasi-RCTs involving adults and children with candidaemia and in which participants were randomized for removal of a CVC (the intervention under study), irrespective of publication status, date of publication, blinding status, outcomes published or language.However, two major factors make the conduct of RCTs in this population a difficult task: the large sample size required to document the impact of catheter removal in terms of overall mortality; and lack of economic interest from the industry in conducting such a trial.

DATA COLLECTION AND ANALYSIS

Our primary outcome measure was mortality. Several secondary outcome measures such as required time for clearance of blood cultures for Candida species, frequency of persistent candidaemia, complications, duration of mechanical ventilation and length of stay in the intensive care unit (ICU) and in the hospital were planned, as were various subgroup and sensitivity analyses, according to our protocol. We assessed papers and abstracts for eligibility and resolved disagreements by discussion. However, we were not able to include any RCTs or quasi-RCTS in this review and, as a result, have carried out no meta-analyses. However, we have chosen to provide a brief overview of excluded observational studies.

MAIN RESULTS

We found no RCT and thus no available data for evaluation of the primary outcome (mortality) nor secondary outcomes or adverse effects. Therefore, we conducted no statistical analysis.A total of 73 observational studies reported on various clinically relevant outcomes following catheter removal or catheter retention. Most of these excluded, observational studies reported a beneficial effect of catheter removal in patients with candidaemia. None of the observational studies reported results in favour of retaining a catheter. However, the observational studies were very heterogeneous with regards to population, pathogens and interventions. Furthermore, they suffered from confounding by indication and an overall high risk of bias. As a consequence, we are not able to provide recommendations or to draw firm conclusions because of the difficulties involved in interpreting the results of these observational studies (very low quality of evidence, GRADE - Grades of Recommendation, Assessment, Development and Evaluation Working Group).

AUTHORS' CONCLUSIONS

Despite indications from observational studies in favour of early catheter removal, we found no eligible RCTs or quasi-RCTs to support these practices and therefore could draw no firm conclusions. At this stage, RCTs have provided no evidence to support the benefit of early or late catheter removal for survival or other important outcomes among patients with candidaemia; no evidence with regards to assessment of harm or benefit with prompt central venous catheter removal and subsequent re-insertion of new catheters to continue treatment; and no evidence on optimal timing of insertion of a new central venous catheter.

Intravenous immune globulin and thromboembolic adverse events: A systematic review and meta-analysis of RCTs

Prior case reports and observational studies indicate that intravenous immune globulin (IVIg) products may cause thromboembolic events (TEEs), leading the FDA to require a boxed warning in 2013. The effect of IVIg treatment on the risk of serious TEEs (acute myocardial infarction, ischemic stroke, or venous thromboembolism) was assessed using adverse event data reported in randomized controlled trials (RCTs) of IVIg. RCTs of IVIg in adult patients from 1995 to 2015 were identified from Pubmed, Embase, ClinicalTrials.Gov, and two large prior reviews of IVIg's therapeutic applications. Trials at high risk of detection or reporting bias for serious adverse events were excluded. 31 RCTs with a total of 4,129 participants (2,318 IVIg-treated, 1,811 control) were eligible for quantitative synthesis. No evidence was found of increased TEE risk among IVIg-treated patients compared with control patients (odds ratio = 1.10, 95% CI: 0.44, 2.88; risk difference = 0.0%, 95% CI: -0.7%, 0.7%, I(2)  = 0%). No significant increase in risk was found when arterial and venous TEEs were analyzed as separate endpoints. Trial publications provided little specific information concerning the methods used to ascertain potential adverse events. Care should be taken in extrapolating the results to patients with higher baseline risks of TEE. Am. J. Hematol. 91:594-605, 2016. © 2016 Wiley Periodicals, Inc.

Comparative Safety of Pharmacologic Treatments for Persistent Depressive Disorder: A Systematic Review and Network Meta-Analysis

We aimed to compare the safety of antidepressants for the treatment of persistent depressive disorder (PDD) with each other and with placebo. We conducted a systematic electronic search and included randomized controlled trials that investigated antidepressants for the treatment of PDD in adults. Outcomes were the incidence of experiencing any adverse event, specific adverse events and related treatment discontinuations. We analyzed the data using traditional and network meta-analyses. Thirty-four studies that comprised 4,769 patients and examined 20 individual agents in nine substance classes were included. Almost all analyzed substance classes were associated with higher discontinuation rates than placebo including tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), antipsychotics, and the serotonin antagonist and reuptake inhibitor (SARI) trazodone. The odds of experiencing any adverse event were significantly higher for TCAs and serotonin noradrenaline reuptake inhibitors (SNRIs) compared to placebo. Pairwise comparisons among the substance classes revealed that more patients receiving TCAs or SNRIs experienced any adverse event and that more patients receiving TCAs or the SARI trazodone discontinued treatment. The complementary treatment with acetyl-l-carnitine showed lower rates of experiencing any adverse event and related discontinuations than all other comparators. TCAs were primarily associated with (anti-)cholinergic and sedating adverse events. SSRIs primarily showed gastrointestinal adverse events. Patients treated with the antipsychotic amisulpride were more likely to manifest weight gain and endocrine adverse events. The comparative evidence for further agents was insufficient or lacking. The identified safety differences may be used to inform the selection among the antidepressants.

Reporting of harms outcomes: a comparison of journal publications with unpublished clinical study reports of orlistat trials

BACKGROUND

The quality of harms reporting in journal publications is often poor, which can impede the risk-benefit interpretation of a clinical trial. Clinical study reports can provide more reliable, complete, and informative data on harms compared to the corresponding journal publication. This case study compares the quality and quantity of harms data reported in journal publications and clinical study reports of orlistat trials.

METHODS

Publications related to clinical trials of orlistat were identified through comprehensive literature searches. A request was made to Roche (Genentech; South San Francisco, CA, USA) for clinical study reports related to the orlistat trials identified in our search. We compared adverse events, serious adverse events, and the reporting of 15 harms criteria in both document types and compared meta-analytic results using data from the clinical study reports against the journal publications.

RESULTS

Five journal publications with matching clinical study reports were available for five independent clinical trials. Journal publications did not always report the complete list of identified adverse events and serious adverse events. We found some differences in the magnitude of the pooled risk difference between both document types with a statistically significant risk difference for three adverse events and two serious adverse events using data reported in the clinical study reports; these events were of mild intensity and unrelated to the orlistat. The CONSORT harms reporting criteria were often satisfied in the methods section of the clinical study reports (70-90 % of the methods section criteria satisfied in the clinical study reports compared to 10-50 % in the journal publications), but both document types satisfied 80-100 % of the results section criteria, albeit with greater detail being provided in the clinical study reports.

CONCLUSIONS

In this case study, journal publications provided insufficient information on harms outcomes of clinical trials and did not specify that a subset of harms data were being presented. Clinical study reports often present data on harms, including serious adverse events, which are not reported or mentioned in the journal publications. Therefore, clinical study reports could support a more complete, accurate, and reliable investigation, and researchers undertaking evidence synthesis of harm outcomes should not rely only on incomplete published data that are presented in the journal publications.

Drug safety meta-analysis: promises and pitfalls

Meta-analysis has increasingly been used to identify adverse effects of drugs and vaccines, but the results have often been controversial. In one respect, meta-analysis is an especially appropriate tool in these settings. Efficacy studies are often too small to reliably assess risks that become important when a medication is in widespread use, so meta-analysis, which is a statistically efficient way to pool evidence from similar studies, seems like a natural approach. But, as the examples in this paper illustrate, different syntheses can come to qualitatively different conclusions, and the results of any one analysis are usually not as precise as they seem to be. There are three reasons for this: the adverse events of interest are rare, standard meta-analysis methods may not be appropriate for the clinical and methodological heterogeneity that is common in these studies, and adverse effects are not always completely or consistently reported. To address these problems, analysts should explore heterogeneity and use random-effects or more complex statistical methods, and use multiple statistical models to see how dependent the results are to the choice of models.

The efficacy and safety of triple inhaled treatment in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis using Bayesian methods

PURPOSE

Although tiotropium (TIO) and inhaled corticosteroid (ICS)/long-acting β-agonists are frequently prescribed together, the efficacy of "triple therapy" has not been scientifically demonstrated. We conducted a systematic review and meta-analysis using Bayesian methods to compare triple therapy and TIO monotherapy.

METHODS

We searched the MEDLINE, EMBASE, and Cochrane Library databases for randomized controlled trials comparing the efficacy and safety of triple therapy and TIO monotherapy in patients with chronic obstructive pulmonary disease (COPD). We conducted a meta-analysis to compare the effectiveness and safety of triple therapy and TIO monotherapy using Bayesian random effects models.

RESULTS

Seven trials were included, and the risk of bias in the majority of the studies was acceptable. There were no statistically significant differences in the incidence of death and acute exacerbation of disease in the triple therapy and TIO monotherapy groups. Triple therapy improved the prebronchodilator forced expiratory volume in 1 second (mean difference [MD], 63.68 mL; 95% credible interval [CrI], 45.29-82.73), and patients receiving triple therapy showed more improvement in St George Respiratory Questionnaire scores (MD, -3.11 points; 95% CrI, -6.00 to -0.80) than patients receiving TIO monotherapy. However, both of these differences were lower than the minimal clinically important difference (MCID). No excessive adverse effects were reported in triple therapy group.

CONCLUSION

Triple therapy with TIO and ICSs/long-acting β-agonists was only slightly more efficacious than TIO monotherapy in treating patients with COPD. Further investigations into the efficacy of new inhaled drugs are needed.

Prothrombin complex concentrate for reversal of vitamin K antagonist treatment in bleeding and non-bleeding patients

BACKGROUND

Treatment with vitamin K antagonists is associated with increased morbidity and mortality. Reversal therapy with prothrombin complex concentrate (PCC) is used increasingly and is recommended in the treatment of patients with bleeding complications undertaking surgical interventions, as well as patients at high risk of bleeding. Evidence is lacking regarding indication, dosing, efficacy and safety.

OBJECTIVES

We assessed the benefits and harms of PCC compared with fresh frozen plasma in the acute medical and surgical setting involving vitamin K antagonist-treated bleeding and non-bleeding patients. We investigated various outcomes and predefined subgroups and performed sensitivity analysis. We examined risks of bias and applied trial sequential analyses (TSA) to examine the level of evidence, and we prepared a 'Risk of bias' table to test the quality of the evidence.

SEARCH METHODS

We searched the following databases from inception to 1 May 2013: Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE (Ovid SP); EMBASE (Ovid SP); International Web of Science; Latin American and Caribbean Health Sciences Literature (LILACS) (via BIREME); the Chinese Biomedical Literature Database; advanced Google and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We applied a systematic and sensitive search strategy to identify relevant randomized clinical trials and imposed no language or date restrictions. We adapted our MEDLINE search strategy for searches in all other databases. We reran the search in October 2014 and found one potential new study of interest. We added this study to a list of 'Studies awaiting classification', and we will incorporate this study into the formal review findings at the time of the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), irrespective of publication status, date of publication, blinding status, outcomes published or language. We contacted investigators and study authors to request relevant data.

DATA COLLECTION AND ANALYSIS

Three review authors independently abstracted data and resolved disagreements by discussion. Our primary outcome measures were 'overall mortality longest follow-up' and 'overall 28-day mortality'. We performed subgroup analyses to assess the effects of PCC in adults in terms of various clinical and physiological outcomes. We presented pooled estimates of the effects of interventions on dichotomous outcomes as risk ratios (RRs), and on continuous outcomes as mean differences (MDs), with 95% confidence intervals (CIs). We assessed risk of bias by assessing trial methodological components and risk of random error through TSA.

MAIN RESULTS

We included four RCTs with a total of 453 participants and determined that none of these trials had overall low risk of bias. We found six ongoing trials from which we were unable to retrieve further data. Three trials provided data on mortality. Meta-analysis showed no statistical effect on overall mortality (RR 0.93, 95% CI 0.37 to 2.33; very low quality of evidence). We were unable to associate use of PCC with the number of complications probably related to the intervention (RR 0.92, 95% CI 0.78 to 1.09; very low quality of evidence). Lack of transfusion data and apparent differences in study design prevented review authors from finding a beneficial effect of PCC in reducing the volume of fresh frozen plasma (FFP) transfused to reverse the effect of vitamin K antagonist treatment. The number of new occurrences of transfusion of red blood cells (RBCs) did not seem to be associated with the use of PCC (RR 1.08, 95% CI 0.82 to 1.43; very low quality of evidence). Still, the included studies demonstrate the possibility of equally reversing vitamin K-induced coagulopathy using PCC without the need for transfusion of FFP. No effect on other predefined outcomes was observed.

AUTHORS' CONCLUSIONS

In the four included RCTs, use of prothrombin complex concentrate does not appear to reduce mortality or transfusion requirements but demonstrates the possibility of reversing vitamin K-induced coagulopathy without the need for transfusion of fresh frozen plasma. All included trials have high risk of bias and are underpowered to detect mortality, benefit or harm. Clinical and statistical heterogeneity is high, and definitions of clinically important outcomes such as adverse events are highly dissimilar between trials. Only weak observational evidence currently supports the use of PCC in vitamin K antagonist-treated bleeding and non-bleeding patients, and the current systematic review of RCTs does not support the routine use of PCC over FFP. Additional high-quality research is urgently needed.

The effects of high perioperative inspiratory oxygen fraction for adult surgical patients

BACKGROUND

Available evidence on the effects of a high fraction of inspired oxygen (FIO2) of 60% to 90% compared with a routine fraction of inspired oxygen of 30% to 40%, during anaesthesia and surgery, on mortality and surgical site infection has been inconclusive. Previous trials and meta-analyses have led to different conclusions on whether a high fraction of supplemental inspired oxygen during anaesthesia may decrease or increase mortality and surgical site infections in surgical patients.

OBJECTIVES

To assess the benefits and harms of an FIO2 equal to or greater than 60% compared with a control FIO2 at or below 40% in the perioperative setting in terms of mortality, surgical site infection, respiratory insufficiency, serious adverse events and length of stay during the index admission for adult surgical patients.We looked at various outcomes, conducted subgroup and sensitivity analyses, examined the role of bias and applied trial sequential analysis (TSA) to examine the level of evidence supporting or refuting a high FIO2 during surgery, anaesthesia and recovery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, BIOSIS, International Web of Science, the Latin American and Caribbean Health Science Information Database (LILACS), advanced Google and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) up to February 2014. We checked the references of included trials and reviews for unidentified relevant trials and reran the searches in March 2015. We will consider two studies of interest when we update the review.

SELECTION CRITERIA

We included randomized clinical trials that compared a high fraction of inspired oxygen with a routine fraction of inspired oxygen during anaesthesia, surgery and recovery in individuals 18 years of age or older.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We conducted random-effects and fixed-effect meta-analyses, and for dichotomous outcomes, we calculated risk ratios (RRs). We used published data and data obtained by contacting trial authors.To minimize the risk of systematic error, we assessed the risk of bias of the included trials. To reduce the risk of random errors caused by sparse data and repetitive updating of cumulative meta-analyses, we applied trial sequential analyses. We used Grades of Recommendation, Assessment, Development and Evaluation (GRADE) to assess the quality of the evidence.

MAIN RESULTS

We included 28 randomized clinical trials (9330 participants); in the 21 trials reporting relevant outcomes for this review, 7597 participants were randomly assigned to a high fraction of inspired oxygen versus a routine fraction of inspired oxygen.In trials with an overall low risk of bias, a high fraction of inspired oxygen compared with a routine fraction of inspired oxygen was not associated with all-cause mortality (random-effects model: RR 1.12, 95% confidence interval (CI) 0.93 to 1.36; GRADE: low quality) within the longest follow-up and within 30 days of follow-up (Peto odds ratio (OR) 0.99, 95% CI 0.61 to 1.60; GRADE: low quality). In a trial sequential analysis, the required information size was not reached and the analysis could not refute a 20% increase in mortality. Similarly, when all trials were included, a high fraction of inspired oxygen was not associated with all-cause mortality to the longest follow-up (RR 1.07, 95% CI 0.87 to 1.33) or within 30 days of follow-up (Peto OR 0.83, 95% CI 0.54 to 1.29), both of very low quality according to GRADE. Neither was a high fraction of inspired oxygen associated with the risk of surgical site infection in trials with low risk of bias (RR 0.86, 95% CI 0.63 to 1.17; GRADE: low quality) or in all trials (RR 0.87, 95% CI 0.71 to 1.07; GRADE: low quality). A high fraction of inspired oxygen was not associated with respiratory insufficiency (RR 1.25, 95% CI 0.79 to 1.99), serious adverse events (RR 0.96, 95% CI 0.65 to 1.43) or length of stay (mean difference -0.06 days, 95% CI -0.44 to 0.32 days).In subgroup analyses of nine trials using preoperative antibiotics, a high fraction of inspired oxygen was associated with a decrease in surgical site infections (RR 0.76, 95% CI 0.60 to 0.97; GRADE: very low quality); a similar effect was noted in the five trials adequately blinded for the outcome assessment (RR 0.79, 95% CI 0.66 to 0.96; GRADE: very low quality). We did not observe an effect of a high fraction of inspired oxygen on surgical site infections in any other subgroup analyses.

AUTHORS' CONCLUSIONS

As the risk of adverse events, including mortality, may be increased by a fraction of inspired oxygen of 60% or higher, and as robust evidence is lacking for a beneficial effect of a fraction of inspired oxygen of 60% or higher on surgical site infection, our overall results suggest that evidence is insufficient to support the routine use of a high fraction of inspired oxygen during anaesthesia and surgery. Given the risk of attrition and outcome reporting bias, as well as other weaknesses in the available evidence, further randomized clinical trials with low risk of bias in all bias domains, including a large sample size and long-term follow-up, are warranted.

The prevalence of occult leiomyosarcoma at surgery for presumed uterine fibroids: a meta-analysis

There is a concern regarding the risk of occult leiomyosarcomas found at surgery for presumed benign fibroids. We sought to produce a comprehensive review of published data addressing this issue and provide high-quality prevalence estimates for clinical practice and future research. A comprehensive literature search using the PubMed/MEDLINE database and the Cochrane Library was performed. Inclusion criteria were human studies, peer-reviewed, with original data, involving cases for surgery in which fibroid-related indications were the primary reason for surgery, and histopathology was provided. Candidate studies (4864) were found; 3844 were excluded after review of the abstract. The remaining 1020 manuscripts were reviewed in their entirety, and 133 were included in the Bayesian binomial random effect meta-analysis. The estimated rate of leiomyosarcoma was 0.51 per 1000 procedures (95 % credible interval (CrI) 0.16–0.98) or approximately 1 in 2000. Restricting the meta-analysis to the 64 prospective studies resulted in a substantially lower estimate of 0.12 leiomyosarcomas per 1000 procedures (95 % CrI <0.01–0.75) or approximately 1 leiomyosarcoma per 8300 surgeries. Results suggest that the prevalence of occult leiomyosarcomas at surgery for presumed uterine fibroids is much less frequent than previously estimated. This rate should be incorporated into both clinical practice and future research.