Indirect comparisons of treatments based on systematic reviews of randomised controlled trials

The consequences of AI training on human decision-making

AI is now an integral part of everyday decision-making, assisting us in both routine and high-stakes choices. These AI models often learn from human behavior, assuming this training data is unbiased. However, we report five studies that show that people change their behavior to instill desired routines into AI, indicating this assumption is invalid. To show this behavioral shift, we recruited participants to play the ultimatum game, where they were asked to decide whether to accept proposals of monetary splits made by either other human participants or AI. Some participants were informed their choices would be used to train an AI proposer, while others did not receive this information. Across five experiments, we found that people modified their behavior to train AI to make fair proposals, regardless of whether they could directly benefit from the AI training. After completing this task once, participants were invited to complete this task again but were told their responses would not be used for AI training. People who had previously trained AI persisted with this behavioral shift, indicating that the new behavioral routine had become habitual. This work demonstrates that using human behavior as training data has more consequences than previously thought since it can engender AI to perpetuate human biases and cause people to form habits that deviate from how they would normally act. Therefore, this work underscores a problem for AI algorithms that aim to learn unbiased representations of human preferences.

Low awareness of the transitivity assumption in complex networks of interventions: a systematic survey from 721 network meta-analyses

BACKGROUND

The transitivity assumption is the cornerstone of network meta-analysis (NMA). Violating transitivity compromises the credibility of the indirect estimates and, by extent, the estimated treatment effects of the comparisons in the network. The present study offers comprehensive empirical evidence on the completeness of reporting and evaluating transitivity in systematic reviews with multiple interventions.

METHODS

We screened the datasets of two previous empirical studies, resulting in 361 systematic reviews with NMA published between January 2011 and April 2015. We updated our evidence base with an additional 360 systematic reviews with NMA published between 2016 and 2021, employing a pragmatic approach. We devised assessment criteria for reporting and evaluating transitivity using relevant methodological literature and compared their reporting frequency before and after the PRISMA-NMA statement.

RESULTS

Systematic reviews published after PRISMA-NMA were more likely to provide a protocol (odds ratio (OR): 3.94, 95% CI: 2.79-5.64), pre-plan the transitivity evaluation (OR: 3.01, 95% CI: 1.54-6.23), and report the evaluation and results (OR: 2.10, 95% CI: 1.55-2.86) than those before PRISMA-NMA. However, systematic reviews after PRISMA-NMA were less likely to define transitivity (OR: 0.57, 95% CI: 0.42-0.79) and discuss the implications of transitivity (OR: 0.48, 95% CI: 0.27-0.85) than those published before PRISMA-NMA. Most systematic reviews evaluated transitivity statistically than conceptually (40% versus 12% before PRISMA-NMA, and 54% versus 11% after PRISMA-NMA), with consistency evaluation being the most preferred (34% before versus 47% after PRISMA-NMA). One in five reviews inferred the plausibility of the transitivity (22% before versus 18% after PRISMA-NMA), followed by 11% of reviews that found it difficult to judge transitivity due to insufficient data. In justifying their conclusions, reviews considered mostly the comparability of the trials (24% before versus 30% after PRISMA-NMA), followed by the consistency evaluation (23% before versus 16% after PRISMA-NMA).

CONCLUSIONS

Overall, there has been a slight improvement in reporting and evaluating transitivity since releasing PRISMA-NMA, particularly in items related to the systematic review report. Nevertheless, there has been limited attention to pre-planning the transitivity evaluation and low awareness of the conceptual evaluation methods that align with the nature of the assumption.

Twenty years of network meta-analysis: Continuing controversies and recent developments

Network meta-analysis (NMA) is an extension of pairwise meta-analysis (PMA) which combines evidence from trials on multiple treatments in connected networks. NMA delivers internally consistent estimates of relative treatment efficacy, needed for rational decision making. Over its first 20 years NMA's use has grown exponentially, with applications in both health technology assessment (HTA), primarily re-imbursement decisions and clinical guideline development, and clinical research publications. This has been a period of transition in meta-analysis, first from its roots in educational and social psychology, where large heterogeneous datasets could be explored to find effect modifiers, to smaller pairwise meta-analyses in clinical medicine on average with less than six studies. This has been followed by narrowly-focused estimation of the effects of specific treatments at specific doses in specific populations in sparse networks, where direct comparisons are unavailable or informed by only one or two studies. NMA is a powerful and well-established technique but, in spite of the exponential increase in applications, doubts about the reliability and validity of NMA persist. Here we outline the continuing controversies, and review some recent developments. We suggest that heterogeneity should be minimized, as it poses a threat to the reliability of NMA which has not been fully appreciated, perhaps because it has not been seen as a problem in PMA. More research is needed on the extent of heterogeneity and inconsistency in datasets used for decision making, on formal methods for making recommendations based on NMA, and on the further development of multi-level network meta-regression.

Omega-3 fatty acids in parenteral nutrition - A systematic review with network meta-analysis on clinical outcomes

BACKGROUND & AIMS

Accumulating scientific evidence supports the benefits of parenteral nutrition (PN) with fish oil (FO) containing intravenous lipid emulsions (ILEs) on clinical outcomes. Yet, the question of the most effective ILE remains controversial. We conducted a network meta-analysis (NMA) to compare and rank different types of ILEs in terms of their effects on infections, sepsis, ICU and hospital length of stay, and in-hospital mortality in adult patients.

METHODS

MEDLINE, EMBASE, and Web of Science databases were searched for randomized controlled trials (RCTs) published up to May 2022, investigating ILEs as a part of part of PN covering at least 70% of total energy provision. Lipid emulsions were classified in four categories: FO-ILEs, olive oil (OO)-ILEs, medium-chain triglyceride (MCT)/soybean oil (SO)-ILEs, and pure SO-ILEs. Data were statistically combined through Bayesian NMA and the Surface Under the Cumulative RAnking (SUCRA) was calculated for all outcomes.

RESULTS

1651 publications were retrieved in the original search, 47 RCTs were included in the NMA. For FO-ILEs, very highly credible reductions in infection risk versus SO-ILEs [odds ratio (OR) = 0.43 90% credibility interval (CrI) (0.29-0.63)], MCT/soybean oil-ILEs [0.59 (0.43-0.82)], and OO-ILEs [0.56 (0.33-0.91)], and in sepsis risk versus SO-ILEs [0.22 (0.08-0.59)], as well as substantial reductions in hospital length of stay versus SO-ILEs [mean difference (MD) = -2.31 (-3.14 to -1.59) days] and MCT/SO-ILEs (-2.01 (-2.82 to -1.22 days) were shown. According to SUCRA score, FO-ILEs were ranked first for all five outcomes.

CONCLUSIONS

In hospitalized patients, FO-ILEs provide significant clinical benefits over all other types of ILEs, ranking first for all outcomes investigated.

REGISTRATION NO

PROSPERO 2022 CRD42022328660.

Comparative effectiveness and safety of direct acting oral anticoagulants in nonvalvular atrial fibrillation for stroke prevention: a systematic review and meta-analysis

PURPOSE

To systematically review available evidence of indirect comparisons from RCTs and direct comparisons from observational studies regarding the comparative effectiveness and safety of DOACs in patients with AF.

METHODS

Electronic databases including EMBASE, MEDLINE, and PUBMED were searched up to June 5th, 2020. Primary endpoints included effectiveness (stroke or systemic embolism [SE]) and safety (major bleeding) outcomes. Bucher methods and random-effects models were conducted for indirect and direct comparisons among DOACs, respectively. Ranking probability analyses and the number needed to treat for net effect (NNTnet) were applied.

RESULTS

A total of 36 studies, involving 7 RCTs (n = 60,292 patients) and 29 observational studies (n = 1,164,821 patients), were included for analyses. Regarding the risk of stroke/SE, no significant differences were found from indirect comparisons of RCTs among the DOACs. For major bleeding, apixaban tended to be safer than rivaroxaban and dabigatran based on both direct and indirect comparisons (all p < 0.05; evidence quality: very low to moderate). Ranking probability analysis showed that apixaban had a high probability of being the best treatment in decreased risk of stroke/SE and major bleeding (80.30% and 91.30%, respectively). Likewise, apixaban was found to have the highest net clinical benefit (0.02, 95% CI: 0.014-0.029) and smallest NNTnet (48, 95% CI: 35-74).

CONCLUSIONS

Apixaban appeared to have a favorable effectiveness-safety profile compared with the other DOACs in AF for stroke prevention, based on evidence from both direct and indirect comparisons. However, additional high-quality evidence is needed to support firm recommendations on clinical decision-making.

Investigation on the Efficiency of Chinese Herbal Injections for Treating Non-small Cell Lung Cancer With Vinorelbine and Cisplatin Based on Multidimensional Bayesian Network Meta-Analysis

Background: As non-small cell lung cancer (NSCLC) seriously threatens human health, several clinical studies have reported that Chinese herbal injections (CHIs) combined with vinorelbine and cisplatin (NP) are beneficial. This multidimensional network meta-analysis was performed to explore the preferable options among different CHIs for treating NSCLC.

Methods: A literature search was performed in several databases to identify randomized controlled trials (RCTs) of CHIs in the treatment of NSCLC from inception to January 31, 2019. Final included studies met the eligibility criteria and methodological quality recommendations. Data analysis was performed using Stata 13.0 and WinBUGS 14.0 software. Each outcome was presented as an odds ratio and the surface under the cumulative ranking curve value (SCURA). The “scatterplot3d” package in R 3.6.1 software was used to perform multidimensional cluster analysis.

Results: Ultimately, 97 eligible RCTs involving 7,440 patients and 14 CHIs were included in this network meta-analysis. Combined with NP chemotherapy, Kanglaite injection plus NP exhibited a better impact on the clinical effectiveness rate (SCURA probability: 78.34%), and Javanica oil emulsion injection plus NP was better in the performance status (95.44%). Huachansu injection plus NP was dominant in reducing thrombocytopenia (92.67%) and gastrointestinal reactions (92.52%). As to multidimensional cluster analysis, Shenmai injection plus NP was superior considering improving the clinical effectiveness rate, performance status and relieving leukopenia.

Conclusions: The combination of CHIs and NP has a better impact on patients with NSCLC than NP alone. Among them, Shenmai injection plus NP, Kanglaite injection plus NP and Javanica oil emulsion injection plus NP were notable. Nevertheless, more multicenter and better designed RCTs are needed to validate our findings.

Comparative Effects Between Direct Oral Anticoagulants for Acute Venous Thromboembolism: Indirect Comparison From Randomized Controlled Trials

Background: There is no direct comparison from clinical trials amongst the direct oral anticoagulants (DOACs) in patients with acute venous thromboembolism (VTE), leaving an evidence gap in decision-making regarding the choice of a DOAC.

Methods: We performed a systematic review for an indirect comparison from randomized controlled trials (RCTs) for comparative effects amongst DOACs in the patients with acute VTE.

Results: A total of 16 RCTs were included for analyses, among which three for dabigatran (n = 7,963 patients), six rivaroxaban (n = 17,935), five apixaban (n = 12,823), and two edoxaban (n = 9,286). There was no significant difference in risk of recurrent VTE (evidence quality: low) and major bleeding (evidence quality: very low) for treatment effects between the four DOACs. Albeit non-significantly, apixaban seemed to have a lowest risk of major bleeding while rivaroxaban had a smallest risk of VTE. Although in general all the included trials were comparable, data from the included trials indicated that the assumption of transitivity may be challenged. Further methodological research including simulation studies, using a net-benefit or benefit-harm approach, running ranking probability analysis, and developing decision aids with machine-learning may be a worthwhile endeavor to help with the choice of DOACs in patients with acute VTE.

Conclusions: To conclude, based on results from the indirect comparison no significant difference in the efficacy and safety was found among the DOACs in patients with acute VTE. More evidence from direct comparative trials is needed to further inform the choice of DOACs in patients with acute VTE.

Safety and efficacy of non-vitamin K antagonist oral anticoagulants in elderly patients with atrial fibrillation: systematic review and meta-analysis of 22 studies and 440 281 patients

AIMS

The aim of the present meta-analysis was to evaluate the efficacy and safety of non-vitamin K oral antagonists (NOACs) vs. vitamin K antagonists (VKAs) in elderly patients with atrial fibrillation (AF) and indirectly compare NOACs in this population.

METHODS AND RESULTS

MEDLINE, Cochrane, ISI Web of Sciences, and SCOPUS were searched for randomized or adjusted observational studies comparing NOACs vs. VKAs for stroke prevention in AF patients ≥75 years. The primary efficacy and safety outcomes of this meta-analysis were the composite of stroke and systemic embolism (SSE) and major bleedings, respectively. Other secondary outcomes were also analysed. The analysis included 22 studies enrolling 440 281 AF patients ≥ 75 years. The risk of SSE was significantly lower with NOACs vs. VKAs [hazard ratio (HR) 0.79; 95% confidence interval (CI) 0.70-0.89], whereas no differences were found for major bleedings (HR 0.94; 95% CI 0.85-1.05). NOACs reduced the risk of intracranial bleeding (HR 0.46; 95% CI 0.38-0.58), haemorrhagic stroke (HR 0.61; 95% CI 0.48-0.79) and fatal bleeding (HR 0.46; 95% CI 0.30-0.72) but increased gastrointestinal (GI) bleedings (HR 1.46; 95% CI 1.30-1.65), compared to VKAs. The adjusted indirect comparison showed no significant differences in term of SSE between NOAC agents. Conversely, the risk of major bleeding was higher for rivaroxaban vs. apixaban (HR 1.69; 95% CI 1.39-2.08) and edoxaban (HR 1.37; 95% CI 1.14-1.67), and for dabigatran vs. apixaban (HR 1.47; 95% CI 1.18-1.85).

CONCLUSION

In elderly patients with AF, NOACs are associated to a lower risk of SSE, intracranial bleeding, haemorrhagic stroke and fatal bleeding than VKAs, but increase GI bleedings. In this analysis, the safety profile of individual NOAC agents was significantly different.

Indirect treatment comparison of valbenazine and deutetrabenazine efficacy and safety in tardive dyskinesia

Aim: Utilize the Bucher indirect treatment comparison (ITC) method to compare valbenazine and deutetrabenazine efficacy using clinical trial data. Methods: Outcomes included mean change from baseline in Abnormal Involuntary Movement Scale (AIMS) total score, AIMS response (≥50% improvement), clinical global impression of change response (score ≤2) and safety outcomes. Data were pooled by trial and dose; outcomes were analyzed at multiple time points. Results: ITC of AIMS score improvement significantly favored valbenazine 80 mg/day at 6 weeks versus deutetrabenazine 36 mg/day at 8 weeks, while valbenazine 40 mg/day was statistically similar to all doses of deutetrabenazine at all time points. No significant differences between drugs were found in AIMS and clinical global impression of change responses and safety outcomes. Conclusion: In this ITC of pooled trial data, valbenazine was generally favorable over deutetrabenazine, although dose titration and equivalency should be considered when interpreting results.

Effectiveness of stop smoking interventions among adults: protocol for an overview of systematic reviews and an updated systematic review

BACKGROUND

Tobacco smoking is the leading cause of cancer, preventable death, and disability. Smoking cessation can increase life expectancy by nearly a decade if achieved in the third or fourth decades of life. Various stop smoking interventions are available including pharmacotherapies, electronic cigarettes, behavioural support, and alternative therapies. This protocol outlines an evidence review which will evaluate the benefits and harms of stop smoking interventions in adults.

METHODS

The evidence review will consist of two stages. First, an overview of systematic reviews evaluating the benefits and harms of various stop smoking interventions delivered in or referred from the primary care setting will be conducted. The second stage will involve updating a systematic review on electronic cigarettes identified in the overview; randomized controlled trials will be considered for outcomes relating to benefits while randomized controlled trials, non-randomized controlled trials, and comparative observational studies will be considered for evaluating harms. Search strategies will be developed and peer-reviewed by medical information specialists. The search strategy for the updated review on e-cigarettes will be developed using that of the candidate systematic review. The MEDLINE®, PsycINFO, Embase, and the Cochrane Library electronic databases will be searched as of 2008 for the overview of reviews and from the last search date of the selected review for the updated review. Organizational websites and trial registries will be searched for unpublished or ongoing reviews/studies. Two reviewers will independently screen the title and abstracts of citations using the liberal accelerated method. Full-text screening will be performed independently by two reviewers. Extracted data will be verified by a second reviewer. Disagreements regarding full-text screening and data extraction will be resolved by consensus or third-party adjudication. The methodological quality of systematic reviews, risk of bias of randomized and non-randomized trials, and methodological quality of cohort studies will be evaluated using AMSTAR 2, the Cochrane risk of bias tool, and a modified version of the Scottish Intercollegiate Guidelines Network critical appraisal tool, respectively. The GRADE framework will be used to assess the quality of the evidence for outcomes.

DISCUSSION

The evidence review will evaluate the benefits and harms of various stop smoking interventions for adults. Findings will be used to inform a national tobacco cessation guideline by the Canadian Task Force on Preventive Health Care.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42018099691, CRD42018099692).

Which treatment is most effective for patients with patellofemoral pain? A protocol for a living systematic review including network meta-analysis

INTRODUCTION

Patellofemoral pain (PFP) affects 1 in every 14 adults. Many treatments for PFP have been evaluated, but the comparative effectiveness of all available treatments has never been examined. Network meta-analysis is the only design to study the comparative effectiveness of all available treatments in one synthesis. This protocol describes the methods for a systematic review including network meta-analysis to assess which treatment is most likely to be effective for patients with PFP.

METHODS AND ANALYSIS

The primary outcome measures of this network meta-analysis are the global rating of change scale at 6-12 weeks, 13-52 weeks and >52 weeks. The secondary outcome measures are patient-rated pain scales at 6-12 weeks, 13-52 weeks and >52 weeks. Completed published and unpublished randomised controlled trials with full-text reports are eligible for inclusion. We will search Embase, PubMed (including MEDLINE), CENTRAL, Scopus, Web of Science, and CINAHL, SPORTDiscus, OpenGrey, WorldCat, conference Proceedings and multiple trial registers for relevant reports. Two researchers will appraise the study eligibility and perform data extraction. Risk of bias will be assessed with the Cochrane Risk of Bias Tool V.2.0.Bayesian network meta-analyses will be constructed for global rating of change scale and patient-rated pain. Consistency between direct and indirect comparisons will be assessed. Between study variability will be explored, and a threshold analysis for the credibility of the network meta-analyses' conclusions will be performed.

ETHICS AND DISSEMINATION

Ethical approval is not required, as this study will be based on published data. The study commenced at 1 February 2018, and its expected completion date is 15 January 2019. Full publication of the work will be sought in an international peer-reviewed journal, as well as translational articles to disseminate the work to clinical practitioners.

PROSPERO REGISTRATION NUMBER

CRD42018079502.

Partially systematic thoughts on the history of systematic reviews

Six years after the launch of Systematic Reviews by Biomed Central, this article is part of the celebration of the journal. It contains personal reflections on the past, present and future of systematic reviews, using examples relevant to the role of systematic reviews in cataloguing and analysing research, assessing quality and planning new studies. The focus is on the most common of the various types of systematic review in health and social care, namely those assessing the effects of interventions.

Borrowing of strength from indirect evidence in 40 network meta-analyses

OBJECTIVES

Network meta-analysis (NMA) is increasingly being used to synthesize direct and indirect evidence and help decision makers simultaneously compare multiple treatments. We empirically evaluate the incremental gain in precision achieved by incorporating indirect evidence in NMAs.

STUDY DESIGN AND SETTING

We performed both network and pairwise meta-analyses on 40 published data sets of multiple-treatment comparisons. Their results were compared using the recently proposed borrowing of strength (BoS) statistic, which quantifies the percentage reduction in the uncertainty of the effect estimate when adding indirect evidence to an NMA.

RESULTS

We analyzed 915 possible treatment comparisons, from which 484 (53%) had no direct evidence (BoS = 100%). In 181 comparisons with only one study contributing direct evidence, NMAs resulted in reduced precision (BoS < 0) and no appreciable improvements in precision (0 < BoS < 30%) for 104 (57.5%) and 23 (12.7%) comparisons, respectively. In 250 comparisons with at least two studies contributing direct evidence, NMAs provided increased precision with BoS ≥ 30% for 166 (66.4%) comparisons.

CONCLUSION

Although NMAs have the potential to provide more precise results than those only based on direct evidence, the incremental gain may reliably occur only when at least two head-to-head studies are available and treatments are well connected. Researchers should routinely report and compare the results from both network and pairwise meta-analyses.

Vaginal progesterone is as effective as cervical cerclage to prevent preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix: updated indirect comparison meta-analysis

BACKGROUND

An indirect comparison meta-analysis published in 2013 reported that both vaginal progesterone and cerclage are equally efficacious for preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic short cervix. The efficacy of vaginal progesterone has been challenged after publication of the OPPTIMUM study. However, this has been resolved by an individual patient-data meta-analysis (Am J Obstet Gynecol. 2018;218:161-180).

OBJECTIVE

To compare the efficacy of vaginal progesterone and cerclage in preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix.

DATA SOURCES

MEDLINE, EMBASE, LILACS, and CINAHL (from their inception to March 2018); Cochrane databases, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials comparing vaginal progesterone to placebo/no treatment or cerclage to no cerclage in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic cervical length <25 mm.

STUDY APPRAISAL AND SYNTHESIS METHODS

Updated systematic review and adjusted indirect comparison meta-analysis of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator. The primary outcomes were preterm birth <35 weeks of gestation and perinatal mortality. Pooled relative risks (RRs) with 95% confidence intervals were calculated.

RESULTS

Five trials comparing vaginal progesterone vs placebo (265 women) and 5 comparing cerclage vs no cerclage (504 women) were included. Vaginal progesterone, compared to placebo, significantly reduced the risk of preterm birth <35 and <32 weeks of gestation, composite perinatal morbidity/mortality, neonatal sepsis, composite neonatal morbidity, and admission to the neonatal intensive care unit (RRs from 0.29 to 0.68). Cerclage, compared to no cerclage, significantly decreased the risk of preterm birth <37, <35, <32, and <28 weeks of gestation, composite perinatal morbidity/mortality, and birthweight <1500 g (RRs from 0.64 to 0.70). Adjusted indirect comparison meta-analyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Vaginal progesterone and cerclage are equally effective for preventing preterm birth and improving perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix. The choice of treatment will depend on adverse events and cost-effectiveness of interventions and patient/physician's preferences.

History and publication trends in the diffusion and early uptake of indirect comparison meta-analytic methods to study drugs: animated coauthorship networks over time

OBJECTIVE

To characterise the early diffusion of indirect comparison meta-analytic methods to study drugs.

DESIGN

Systematic literature synthesis.

DATA SOURCES

Cochrane Database of Systematic Reviews, EMBASE, MEDLINE, Scopus and Web of Science.

STUDY SELECTION

English language papers that used indirect comparison meta-analytic methods to study the efficacy or safety of three or more interventions, where at least one was a drug.

DATA EXTRACTION

The number of publications and authors was plotted by year and type: methodological contribution, review or empirical application. Author and methodological details were summarised for empirical applications, and animated coauthorship networks were created to visualise contributors by country and affiliation type (academia, industry, government or other) over time.

RESULTS

We identified 477 papers (74 methodological contributions, 42 reviews and 361 empirical applications) by 1689 distinct authors from 1997 to 2013. Prior to 2002, only three applications were published, with contributions from the USA (n=2) and Canada (n=1). The number of applications gradually increased annually with rapid uptake between 2011 and 2013 (n=254, 71%). Early diffusion occurred primarily in Europe with the first application credited to the UK in 2003. Application spread to other European countries in 2005, and may have been supported by regulatory requirements for drug approval. By the end of 2013, contributions included 49% credited to Europe (22% UK, 27% other), 37% credited to North America (11% Canada, 26% USA) and 14% from other regions.

CONCLUSION

Indirect comparison meta-analytic methods are an important innovation for health research. Although Canada and the USA were the first to apply these methods, Europe led their diffusion. The increase in uptake of these methods may have been facilitated by acceptance by regulatory agencies, which are calling for more comparative drug effect data to assist in drug accessibility and reimbursement decisions.

Indirect comparison meta-analysis of two enoxaparin regimens in patients undergoing major orthopaedic surgery

Two enoxaparin dosage regimens are used as comparators to evaluate new anticoagulants for thromboprophylaxis in patients undergoing major orthopaedic surgery, but so far no satisfactory direct comparison between them has been published. Our objective was to compare the efficacy and safety of enoxaparin 3,000 anti-Xa IU twice daily and enoxaparin 4,000 anti-Xa IU once daily in this clinical setting by indirect comparison meta-analysis, using Bucher’s method. We selected randomised controlled trials comparing another anticoagulant, placebo (or no treatment) with either enoxaparin regimen for venous thromboembolism prophylaxis after hip or knee replacement or hip fracture surgery, provided that the second regimen was assessed elsewhere versus the same comparator. Two authors independently evaluated study eligibility, extracted the data, and assessed the risk of bias. The primary efficacy outcome was the incidence of venous thomboembolism. The main safety outcome was the incidence of major bleeding. Overall, 44 randomised comparisons in 56,423 patients were selected, 35 being double-blind (54,117 patients). Compared with enoxaparin 4,000 anti-Xa IU once daily, enoxaparin 3,000 anti-Xa IU twice daily was associated with a reduced risk of venous thromboembolism (relative risk [RR]: 0.53, 95% confidence interval [CI]: 0.40 to 0.69), but an increased risk of major bleeding (RR: 2.01, 95% CI: 1.23 to 3.29). In conclusion, when interpreting the benefit-risk ratio of new anticoagulant drugs versus enoxaparin for thromboprophylaxis after major orthopaedic surgery, the apparently greater efficacy but higher bleeding risk of the twice-daily 3,000 anti-Xa IU enoxaparin regimen compared to the once-daily 4,000 anti-Xa IU regimen should be taken into account.

Lipophilic Statin Versus Rosuvastatin (Hydrophilic) Treatment for Heart Failure: a Meta-Analysis and Adjusted Indirect Comparison of Randomised Trials

OBJECTIVES

This study aims to compare lipophilic and hydrophilic statin therapy on clinical outcomes of heart failure (HF) using a systematic review and an adjusted indirect comparison meta-analysis. Outcomes were all-cause mortality, cardiovascular mortality, cardiovascular hospitalization and hospitalization for worsening HF.

METHODS

We conducted a search of PubMed, EMBASE and Cochrane databases until 31st December 2014 for randomized control trials (RCTs) in HF evaluating statins versus placebo. Identified RCTs and their respective abstracted information were grouped according to statin type evaluated and analyzed separately. Outcomes were initially pooled with the Peto's one-step method, producing odd ratios (OR) and 95 % confidence intervals (CI) for each statin type. Using these pooled estimates, we performed adjusted indirect comparisons of lipophilic versus hydrophilic statin for each outcome.

RESULTS

Thirteen studies involving 10,966 patients were identified and analyzed. Lipophilic statins were superior to hydrophilic rosuvastatin regarding all-cause mortality (OR 0 · 50; 95 % CI, 0 · 11-0 · 89; p = 0 · 01), cardiovascular mortality (OR 0 · 61; 0 · 25-0 · 97; p = 0 · 009), and hospitalization for worsening HF (OR 0 · 52; 0 · 21-0 · 83; p = 0 · 0005). However, both statins were comparable with regards to cardiovascular hospitalization [OR 0 · 80 (0 · 31, 1 · 28); p = 0 · 36].

CONCLUSIONS

Lipophilic statin treatment shows significant decreases in all-cause mortality, cardiovascular mortality and hospitalization for worsening HF compared with rosuvastatin treatment. This meta-analysis provides preliminary evidence that lipophilic statins offer better clinical outcomes in HF till data from head to head comparisons are available.

Efficacy of two noninvasive weaning strategies in intubated patients with chronic obstructive pulmonary disease: A meta-analysis and indirect treatment comparison

The purpose of our indirect comparison was to explore the optimal switching time to noninvasive ventilation for further weaning in patients with chronic obstructive pulmonary disease (COPD) undergoing invasive mechanical ventilation. A comprehensive literature search was performed to identify randomized controlled trials comparing noninvasive weaning at spontaneous breathing trial (SBT) failure after meeting simple weaning criteria or at the pulmonary infection control window (PIC window) with conventional invasive weaning in COPD patients. Using conventional invasive weaning as a bridge, we indirectly compared the two noninvasive weaning strategies using the Bucher approach. Noninvasive weaning at SBT failure after meeting simple weaning criteria was associated with an extended duration of endotracheal mechanical ventilation (standardized mean difference 1.90, 95% CI 1.27-2.53, P < 0.001) compared with noninvasive weaning at the PIC window. No significant differences in mortality or the rate of ventilator-associated pneumonia were observed. Our study suggests that the PIC window may be a promising switching time for noninvasive weaning in COPD patients.

GetReal in network meta-analysis: a review of the methodology

Pairwise meta-analysis is an established statistical tool for synthesizing evidence from multiple trials, but it is informative only about the relative efficacy of two specific interventions. The usefulness of pairwise meta-analysis is thus limited in real-life medical practice, where many competing interventions may be available for a certain condition and studies informing some of the pairwise comparisons may be lacking. This commonly encountered scenario has led to the development of network meta-analysis (NMA). In the last decade, several applications, methodological developments, and empirical studies in NMA have been published, and the area is thriving as its relevance to public health is increasingly recognized. This article presents a review of the relevant literature on NMA methodology aiming to pinpoint the developments that have appeared in the field. Copyright © 2016 John Wiley & Sons, Ltd.

Epidural Corticosteroid Injections for Radiculopathy and Spinal Stenosis: A Systematic Review and Meta-analysis

BACKGROUND

Use of epidural corticosteroid injections is increasing.

PURPOSE

To review evidence on the benefits and harms of epidural corticosteroid injections in adults with radicular low back pain or spinal stenosis of any duration.

DATA SOURCES

Ovid MEDLINE (through May 2015), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, prior systematic reviews, and reference lists.

STUDY SELECTION

Randomized trials of epidural corticosteroid injections versus placebo interventions, or that compared epidural injection techniques, corticosteroids, or doses.

DATA EXTRACTION

Dual extraction and quality assessment of individual studies, which were used to determine the overall strength of evidence (SOE).

DATA SYNTHESIS

30 placebo-controlled trials evaluated epidural corticosteroid injections for radiculopathy, and 8 trials were done for spinal stenosis. For radiculopathy, epidural corticosteroids were associated with greater immediate-term reduction in pain (weighted mean difference on a scale of 0 to 100, -7.55 [95% CI, -11.4 to -3.74]; SOE, moderate), function (standardized mean difference after exclusion of an outlier trial, -0.33 [CI, -0.56 to -0.09]; SOE, low), and short-term surgery risk (relative risk, 0.62 [CI, 0.41 to 0.92]; SOE, low). Effects were below predefined minimum clinically important difference thresholds, and there were no longer-term benefits. Limited evidence showed no clear effects of technical factors, patient characteristics, or comparator interventions on estimates. There were no clear effects of epidural corticosteroid injections for spinal stenosis (SOE, low to moderate). Serious harms were rare, but harms reporting was suboptimal (SOE, low).

LIMITATIONS

The review was restricted to English-language studies. Some meta-analyses were based on small numbers of trials (particularly for spinal stenosis), and most trials had methodological shortcomings.

CONCLUSION

Epidural corticosteroid injections for radiculopathy were associated with immediate reductions in pain and function. However, benefits were small and not sustained, and there was no effect on long-term surgery risk. Limited evidence suggested no effectiveness for spinal stenosis.

An assessment of the methodological quality of published network meta-analyses: a systematic review

OBJECTIVE

To assess the methodological quality of published network meta-analysis.

DESIGN

Systematic review.

METHODS

We searched the medical literature for network meta-analyses of pharmaceuticals. We assessed general study characteristics, study transparency and reproducibility, methodological approach, and reporting of findings. We compared studies published in journals with lower impact factors with those published in journals with higher impact factors, studies published prior to January 1st, 2013 with those published after that date, and studies supported financially by industry with those supported by non-profit institutions or that received no support.

RESULTS

The systematic literature search identified 854 citations. Three hundred and eighteen studies met our inclusion criteria. The number of network meta-analyses has grown rapidly, with 48% of studies published since January 2013. The majority of network meta-analyses were supported by a non-profit institution or received no support (68%). We found considerable inconsistencies among reviewed studies. Eighty percent reported search terms, 61% a network diagram, 65% sufficient data to replicate the analysis, and 90% the characteristics of included trials. Seventy percent performed a risk of bias assessment of included trials, 40% an assessment of model fit, and 56% a sensitivity analysis. Among studies with a closed loop, 69% examined the consistency of direct and indirect evidence. Sixty-four percent of studies presented the full matrix of head-to-head treatment comparisons. For Bayesian studies, 41% reported the probability that each treatment was best, 31% reported treatment ranking, and 16% included the model code or referenced publicly-available code. Network meta-analyses published in higher impact factors journals and those that did not receive industry support performed better across the assessment criteria. We found few differences between older and newer studies.

CONCLUSIONS

There is substantial variation in the network meta-analysis literature. Consensus among guidelines is needed improve the methodological quality, transparency, and consistency of study conduct and reporting.

Clinical efficacy of fidaxomicin compared with vancomycin and metronidazole in Clostridium difficile infections: a meta-analysis and indirect treatment comparison

OBJECTIVES

To evaluate the efficacy of fidaxomicin treatment, which has a limited effect on the normal gut flora, compared with vancomycin and metronidazole treatment in Clostridium difficile infections (CDIs).

METHODS

A systematic literature review was conducted in July to August 2011 and updated in July 2013. For fidaxomicin versus vancomycin, efficacy was evaluated using meta-analysis of data from two Phase III direct comparative studies (n = 1164). As there were no studies comparing fidaxomicin and metronidazole, an indirect comparison was made using data from three vancomycin versus metronidazole studies (n = 345), using the methodology of Bucher et al. (J Clin Epidemiol 1997; 50: 683-91). This provides an OR for the indirect comparison of fidaxomicin versus metronidazole when direct evidence of fidaxomicin versus vancomycin and vancomycin versus metronidazole is available.

RESULTS

Clinical cure rates were similar for fidaxomicin and vancomycin; the OR (95% CI) was 1.17 (0.82, 1.66). Recurrence [0.47 (0.34, 0.65)] was significantly lower and sustained cure rates [1.75 (1.35, 2.27)] significantly higher for fidaxomicin than vancomycin. Similar results were obtained in patient subgroups with severe CDI and with non-severe CDI. From the indirect comparison, the likelihood of recurrence [0.42 (0.18, 0.96)] and sustained cure [2.55 (1.44, 4.51)] were significantly improved for fidaxomicin versus metronidazole. Again, similar results were obtained in those with severe and non-severe CDI.

CONCLUSIONS

Fidaxomicin provides improved sustained cure rates in patients with CDI compared with vancomycin. An indirect comparison indicates that the same is also true for fidaxomicin versus metronidazole. In view of these data, fidaxomicin may be considered as first-line therapy for CDI.

Analgesic efficacy of opioids in chronic pain: recent meta-analyses

Opioids are regularly administered in acute and cancer pain. In chronic non-cancer pain (CNCP), however, their use is controversial. Previous meta-analyses and randomized controlled trials (RCTs) lack methodological homogeneity and comparable data. Here we analysed the maximum analgesic efficacies of opioids and non-opioids compared with placebo, and of physiotherapy and psychotherapy compared with active or waiting-list controls. We screened 3647 citations and included RCTs if treatment duration was at least 3 weeks, data were sufficient for meta-analysis, and criteria for high quality were met. Only 46 studies (10 742 patients) met the criteria. Weighted and standardized mean differences (WMD, SMD) between pain intensities were pooled to conduct separate meta-analyses for each treatment category. At the end of treatment the WMD for pain reduction (100-point scale) was 12.0 for 'strong' opioids, 10.6 for 'weak' opioids, 8.4 for non-opioids (each vs. placebo), 5.5 for psychotherapy and 4.5 for physiotherapy (each vs. active controls). Dropout rates were high in pharmacological studies. The 95% confidence intervals using the outcomes of control groups did not indicate statistical differences between efficacies of the five interventions. Because not enough eligible head-to-head trials were available, our analysis is limited to adjusted indirect comparisons. The heterogeneity of pre-post pain differences in control groups did not allow the definition of a common comparator. In conclusion, although there were statistically significant differences between maximum treatment efficacies, no intervention per se produced clinically important improvements in average pain intensity. Thus, opioids alone are inappropriate and multimodal treatment programmes may be required for CNCP.

LINKED ARTICLES

This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.

Edoxaban in the evolving scenario of non vitamin K antagonist oral anticoagulants imputed placebo analysis and multiple treatment comparisons

Background

Edoxaban recently proved non-inferior to warfarin for prevention of thromboembolism in patients with non-valvular atrial fibrillation (AF). We conducted an imputed-placebo analysis with estimates of the proportion of warfarin effect preserved by each non vitamin K antagonist oral anticoagulant (NOAC) and indirect comparisons between edoxaban and different NOACs.

Methods and Findings

We performed a literature search (up to January 2014), clinical trials registers, conference proceedings, and websites of regulatory agencies. We selected non-inferiority randomised controlled phase III trials of dabigatran, rivaroxaban, apixaban and edoxaban compared with adjusted-dose warfarin in non-valvular AF. Compared to imputed placebo, all NOACs reduced the risk of stroke (ORs between 0.24 and 0.42, all p<0.001) and all-cause mortality (ORs between 0.55 and 0.59, all p<0.05). Edoxaban 30 mg and 60 mg preserved 87% and 112%, respectively, of the protective effect of warfarin on stroke, and 133% and 121%, respectively, of the protective effect of warfarin on all-cause mortality. The risk of primary outcome (stroke/systemic embolism), all strokes and ischemic strokes was significantly higher with edoxaban 30 mg than dabigatran 150 mg and apixaban. There were no significant differences between edoxaban 60 mg and other NOACs for all efficacy outcomes except stroke, which was higher with edoxaban 60 mg than dabigatran 150 mg. The risk of major bleedings was lower with edoxaban 30 mg than any other NOAC, odds ratios (ORs) ranging between 0.45 and 0.67 (all p<0.001).

Conclusions

This study suggests that all NOACs preserve a substantial or even larger proportion of the protective warfarin effect on stroke and all-cause mortality. Edoxaban 30 mg is associated with a definitely lower risk of major bleedings than other NOACs. This is counterbalanced by a lower efficacy in the prevention of thromboembolism, although with a final benefit on all-cause mortality.

Reporting of results from network meta-analyses: methodological systematic review

OBJECTIVE

To examine how the results of network meta-analyses are reported.

DESIGN

Methodological systematic review of published reports of network meta-analyses.

DATA SOURCES

Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Medline, and Embase, searched from inception to 12 July 2012.

STUDY SELECTION

All network meta-analyses comparing the clinical efficacy of three or more interventions in randomised controlled trials were included, excluding meta-analyses with an open loop network of three interventions.

DATA EXTRACTION AND SYNTHESIS

The reporting of the network and results was assessed. A composite outcome included the description of the network (number of interventions, direct comparisons, and randomised controlled trials and patients for each comparison) and the reporting of effect sizes derived from direct evidence, indirect evidence, and the network meta-analysis.

RESULTS

121 network meta-analyses (55 published in general journals; 48 funded by at least one private source) were included. The network and its geometry (network graph) were not reported in 100 (83%) articles. The effect sizes derived from direct evidence, indirect evidence, and the network meta-analysis were not reported in 48 (40%), 108 (89%), and 43 (36%) articles, respectively. In 52 reports that ranked interventions, 43 did not report the uncertainty in ranking. Overall, 119 (98%) reports of network meta-analyses did not give a description of the network or effect sizes from direct evidence, indirect evidence, and the network meta-analysis. This finding did not differ by journal type or funding source.

CONCLUSIONS

The results of network meta-analyses are heterogeneously reported. Development of reporting guidelines to assist authors in writing and readers in critically appraising reports of network meta-analyses is timely.

A systematic review and meta-analysis of the evidence base for add-on treatment for patients with major depressive disorder who have not responded to antidepressant treatment: a European perspective

Previous comparative reviews of add-on therapies for patients with major depressive disorder (MDD) with an inadequate response to antidepressants have not used meta-analytic techniques to compare different drug classes and have included non-licensed therapies. This meta-analysis reviewed all published peer-reviewed evidence for the efficacy of EU-licensed therapies in patients with MDD and an inadequate response to antidepressant monotherapy. Papers concerning randomized clinical trials (RCTs) were identified using criteria from the Cochrane Handbook for Systematic Reviews of Interventions. Add-on therapies reviewed were antidepressants, quetiapine XR, lithium, and S-adenosyl-l-methionine (SAMe). Seven RCTs that reported response and remission in a way that allowed quantitative analysis were included in this meta-analysis. Comparison of the different drug classes indicated that most interventions had similar efficacy. The likelihood of response was significantly greater with SAMe versus placebo and lithium and with quetiapine XR versus placebo. Most add-on interventions demonstrated comparable efficacy in patients with MDD and an inadequate response to initial antidepressants. However, there is currently a paucity of high-quality data regarding the use of add-on treatments in patients with MDD who are inadequate responders to antidepressants, with quetiapine XR presenting the most comprehensive evidence base to date.

Progesterone to prevent spontaneous preterm birth

Preterm birth is the leading cause of perinatal morbidity and mortality worldwide, and its prevention is an important healthcare priority. Preterm parturition is one of the 'great obstetrical syndromes' and is caused by multiple etiologies. One of the mechanisms of disease is the untimely decline in progesterone action, which can present as a clinically silent sonographic short cervix in the midtrimester. The detection of a short cervix in the midtrimester is a powerful risk factor for preterm delivery. Vaginal progesterone can reduce the rate of preterm delivery by 45% and the rate of neonatal morbidity (admission to the neonatal intensive care unit, respiratory distress syndrome, need for mechanical ventilation, etc.). To prevent one case of spontaneous preterm birth <33 weeks of gestation, 11 patients with a short cervix would need to be treated (based on an individual patient meta-analysis). Vaginal progesterone reduces the rate of spontaneous preterm birth in women with a short cervix, both with and without a prior history of preterm birth. In patients with a prior history of preterm birth, vaginal progesterone is as effective as cervical cerclage to prevent preterm delivery. 17α-Hydroxyprogesterone caproate has not been shown to be effective in reducing the rate of spontaneous preterm birth in women with a short cervix.

Characteristics of networks of interventions: a description of a database of 186 published networks

Systematic reviews that employ network meta-analysis are undertaken and published with increasing frequency while related statistical methodology is evolving. Future statistical developments and evaluation of the existing methodologies could be motivated by the characteristics of the networks of interventions published so far in order to tackle real rather than theoretical problems. Based on the recently formed network meta-analysis literature we aim to provide an insight into the characteristics of networks in healthcare research. We searched PubMed until end of 2012 for meta-analyses that used any form of indirect comparison. We collected data from networks that compared at least four treatments regarding their structural characteristics as well as characteristics of their analysis. We then conducted a descriptive analysis of the various network characteristics. We included 186 networks of which 35 (19%) were star-shaped (treatments were compared to a common comparator but not between themselves). The median number of studies per network was 21 and the median number of treatments compared was 6. The majority (85%) of the non-star shaped networks included at least one multi-arm study. Synthesis of data was primarily done via network meta-analysis fitted within a Bayesian framework (113 (61%) networks). We were unable to identify the exact method used to perform indirect comparison in a sizeable number of networks (18 (9%)). In 32% of the networks the investigators employed appropriate statistical methods to evaluate the consistency assumption; this percentage is larger among recently published articles. Our descriptive analysis provides useful information about the characteristics of networks of interventions published the last 16 years and the methods for their analysis. Although the validity of network meta-analysis results highly depends on some basic assumptions, most authors did not report and evaluate them adequately. Reviewers and editors need to be aware of these assumptions and insist on their reporting and accuracy.

Review of mixed treatment comparisons in published systematic reviews shows marked increase since 2009

OBJECTIVES

To identify and summarize published systematic reviews that report results of meta-analyses that combined direct and indirect comparisons.

STUDY DESIGN AND SETTING

Narrative review of mixed treatment comparisons (MTCs) reported in systematic reviews of health interventions. MEDLINE, MEDLINE In-Process, Embase, CINAHL, DARE, the Cochrane Database of Systematic Reviews, and SIGLE were searched for reviews published up to June 2012 in which a meta-analysis had been conducted that combined direct and indirect comparisons among more than two interventions.

RESULTS

Reviews reporting MTCs are difficult to identify when searching major databases. These databases offer no way to identify MTCs, and authors use various names when reporting them. Of the 201 eligible reviews identified, more than three-quarters had been published in full. MTC methods have been used to study a wide range of clinical topics. The reported use of these methods has increased rapidly since 2009, and results from MTCs are commonly used in health policy decisions, through the evidence considered in health technology assessments.

CONCLUSION

In view of the increasing use of MTCs, indexing of this study type in databases and a consensus on terminology and standards for conduct and reporting would be timely.

The efficacy and tolerability of perampanel and other recently approved anti-epileptic drugs for the treatment of refractory partial onset seizure: a systematic review and Bayesian network meta-analysis

OBJECTIVES

This paper compares the efficacy and tolerability of perampanel (PER) relative to other recently approved anti-epileptic drug (AEDs) - lacosamide (LCS), retigabine (RTG), and eslicarbazepine (ESL) for the adjunctive treatment of partial onset seizures with or without secondary generalization and specifically in the secondary generalization subgroup.

MATERIALS AND METHODS

A systematic literature review of all RCTs of PER and selected AEDs in EMBASE, Medline, and the Cochrane Central from 1998 to January 2011 with an update in PubMed in March 2013 was performed. A network meta-analysis was conducted for 50% responder rate for overall seizures; withdrawal due to adverse events; seizure freedom; and 50% responder rate for secondary generalized seizures.

RESULTS

Twelve RCTs (three PER, three LCS, three RTG and three ESL) were included. PER performed significantly better than placebo for 'responder rate' (OR 2.151, 95% CrI 1.348-3.472) and 'seizure freedom' (OR 2.507, 95% CrI 1.067-7.429). When compared to other agents, PER was found to be equally effective. For 'withdrawal due to adverse events', PER had the lowest odds ratio vs. placebo compared with other AEDs. In the analysis for the subgroup of patients with secondary generalization, only four RCTs (three PER and one LCS) met the inclusion criteria for one outcome (responder rate) for LCS. In this subgroup, PER was statistically significantly better than placebo (OR 2.448, 95% CrI 1.088-5.828).

CONCLUSION

PER was statistically significantly superior to placebo in responder rate, seizure freedom, and responder rate in the secondary generalization population. Though PER had statistically significant greater withdrawal compared to placebo, it had the lowest ORs vs. placebo, suggesting a superior safety profile among the comparators included in this analysis. In patients with partial onset seizure with secondary generalization, PER had a statistically significant effect on responder rate compared to placebo.

Assessing key assumptions of network meta-analysis: a review of methods

BACKGROUND

Homogeneity and consistency assumptions underlie network meta-analysis (NMA). Methods exist to assess the assumptions but they are rarely and poorly applied. We review and illustrate methods to assess homogeneity and consistency.

METHODS

Eligible articles focussed on indirect comparison or NMA methodology. Articles were sought by hand-searching and scanning references (March 2013). Assumption assessment methods described in the articles were reviewed, and applied to compare anti-malarial drugs.

RESULTS

116 articles were included. Methods to assess homogeneity were: comparing characteristics across trials; comparing trial-specific treatment effects; using hypothesis tests or statistical measures; applying fixed-effect and random-effects pair-wise meta-analysis; and investigating treatment effect-modifiers. Methods to assess consistency were: comparing characteristics; investigating treatment effect-modifiers; comparing outcome measurements in the referent group; node-splitting; inconsistency modelling; hypothesis tests; back transformation; multidimensional scaling; a two-stage approach; and a graph-theoretical method. For the malaria example, heterogeneity existed for some comparisons that was unexplained by investigating treatment effect-modifiers. Inconsistency was detected using node-splitting and inconsistency modelling. It was unclear whether the covariates explained the inconsistency.

CONCLUSIONS

Presently, we advocate applying existing assessment methods collectively to gain the best understanding possible regarding whether assumptions are reasonable. In our example, consistency was questionable; therefore the NMA results may be unreliable.

Indirect comparison of randomised controlled trials: comparative efficacy of dexlansoprazole vs. esomeprazole in the treatment of gastro-oesophageal reflux disease

BACKGROUND

Dexlansoprazole is a new proton pump inhibitor (PPI) with a dual delayed-release system. Both dexlansoprazole and esomeprazole are an enantiomer of lansoprazole and omeprazole respectively. However, there is no head-to-head trial data or indirect comparison analyses between dexlansoprazole and esomeprazole.

AIM

To compare the efficacy of dexlansoprazole with esomeprazole in healing erosive oesophagitis (EO), the maintenance of healed EO and the treatment of non-erosive reflux disease (NERD).

METHODS

Randomised Controlled Trials (RCTs) comparing dexlansoprazole or esomeprazole with either placebo or another PPI were systematically reviewed. Random-effect meta-analyses and adjusted indirect comparisons were conducted to compare the treatment effect of dexlansoprazole and esomeprazole using a common comparator. The relative risk (RR) and 95% confidence interval (CI) were calculated.

RESULTS

The indirect comparisons revealed significant differences in symptom control of heartburn in patients with NERD at 4 weeks. Dexlansoprazole 30 mg was more effective than esomeprazole 20 mg or 40 mg (RR: 2.01, 95% CI: 1.15-3.51; RR: 2.17, 95% CI: 1.39-3.38). However, there were no statistically significant differences between the two drugs in EO healing and maintenance of healed EO. Comparison of symptom control in healed EO was not able to be made due to different definitions used in the RCTs.

CONCLUSIONS

Adjusted indirect comparisons based on currently available RCT data suggested significantly better treatment effect in symptom control of heartburn in patients with NERD for dexlansoprazole against esomeprazole. No statistically significant differences were found in other EO outcomes. However, these study findings need to be interpreted with caution due to small number of studies and other limitations.

Analysis of the systematic reviews process in reports of network meta-analyses: methodological systematic review

OBJECTIVE

To examine whether network meta-analyses, increasingly used to assess comparative effectiveness of healthcare interventions, follow the key methodological recommendations for reporting and conduct of systematic reviews.

DESIGN

Methodological systematic review of reports of network meta-analyses.

DATA SOURCES

Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Medline, and Embase, searched from inception to 12 July 2012.

REVIEW METHODS

All network meta-analyses comparing clinical efficacy of three or more interventions based on randomised controlled trials, excluding meta-analyses with an open loop network of three interventions. We assessed the reporting of general characteristics and key methodological components of the systematic review process using two composite outcomes. For some components, if reporting was adequate, we assessed their conduct quality.

RESULTS

Of 121 network meta-analyses covering a wide range of medical areas, 100 (83%) assessed pharmacological interventions and 11 (9%) non-pharmacological interventions; 56 (46%) were published in journals with a high impact factor. The electronic search strategy for each database was not reported in 88 (73%) network meta-analyses; for 36 (30%), the primary outcome was not clearly identified. Overall, 61 (50%) network meta-analyses did not report any information regarding the assessment of risk of bias of individual studies, and 103 (85%) did not report any methods to assess the likelihood of publication bias. Overall, 87 (72%) network meta-analyses did not report the literature search, searched only one database, did not search other sources, or did not report an assessment of risk of bias of individual studies. These methodological components did not differ by publication in a general or specialty journal or by public or private funding.

CONCLUSIONS

Essential methodological components of the systematic review process-conducting a literature search and assessing risk of bias of individual studies-are frequently lacking in reports of network meta-analyses, even when published in journals with high impact factors.

Prevention of venous thromboembolism with new oral anticoagulants versus standard pharmacological treatment in acute medically ill patients: a systematic review and meta-analysis

INTRODUCTION

Venous thromboembolism (VTE) is a common and potentially avoidable cause of morbidity and mortality in patients hospitalized for acute medical illness.

OBJECTIVE

Our objective was to conduct a systematic review of studies that assessed the efficacy and safety of new oral anticoagulant (OAC) drugs versus standard pharmacological drugs and/or placebo in prevention of VTE in acute medically ill patients.

METHODS

PubMed.org and ClinicalTrials.gov databases were searched to identify studies that evaluated the efficacy and safety of a new OAC versus the standard pharmacological treatment and/or placebo in the prevention of VTE in medically ill patients. Relative risks (RR), weighted means and 95% CIs were calculated. Statistical heterogeneity was evaluated using Chi2 and I2 statistics. Two studies were included in the meta-analysis. The primary outcome in both studies was the composite of VTE-related death, symptomatic non-fatal pulmonary embolism (PE), symptomatic deep venous thrombosis (DVT) and asymptomatic proximal DVT. Both studies compared a factor (F)Xa inhibitor with enoxaparin in standard short-term thromboprophylaxis followed by a period where the FXa inhibitor was compared with placebo as prolonged thromboprophylaxis in medically ill patients. The primary major safety outcome in both studies was a composite of treatment-related major bleeding and clinically relevant non-major bleeding. A total of 14 629 patients were randomized.

RESULTS

Compared with subjects treated with enoxaparin followed by placebo, the RR of the primary outcome during the prolonged treatment period was 0.79 (95% CI 0.66, 0.94), the RR for the primary outcome during the first short-term treatment period was 1.03 (95% CI 0.81, 1.31). For major bleeding during the prolonged treatment period, the RR was 2.69 (95% CI 1.65, 4.39) for patients treated with an FXa inhibitor compared with enoxaparin/placebo. For major bleeding during the shorter treatment period, the RR was 2.01 (95% CI 1.10, 3.65) in favour of enoxaparin.

CONCLUSION

In acute medically ill patients, prolonged thromboprophylaxis with an oral FXa inhibitor is more protective than regular short-term treatment with enoxaparin. However, treatment with FXa inhibitors is significantly associated with major bleeding, both in long- and short-term treatment compared with enoxaparin.

Vaginal progesterone vs. cervical cerclage for the prevention of preterm birth in women with a sonographic short cervix, previous preterm birth, and singleton gestation: a systematic review and indirect comparison metaanalysis

OBJECTIVE

No randomized controlled trial has compared vaginal progesterone and cervical cerclage directly for the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous spontaneous preterm birth. We performed an indirect comparison of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator.

STUDY DESIGN

Adjusted indirect metaanalysis of randomized controlled trials.

RESULTS

Four studies that evaluated vaginal progesterone vs placebo (158 patients) and 5 studies that evaluated cerclage vs no cerclage (504 patients) were included. Both interventions were associated with a statistically significant reduction in the risk of preterm birth at <32 weeks of gestation and composite perinatal morbidity and mortality compared with placebo/no cerclage. Adjusted indirect metaanalyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Based on state-of-the-art methods for indirect comparisons, either vaginal progesterone or cerclage are equally efficacious in the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous preterm birth. Selection of the optimal treatment needs to consider adverse events, cost and patient/clinician preferences.

Methods for the drug effectiveness review project

The Drug Effectiveness Review Project was initiated in 2003 in response to dramatic increases in the cost of pharmaceuticals, which lessened the purchasing power of state Medicaid budgets. A collaborative group of state Medicaid agencies and other organizations formed to commission high-quality comparative effectiveness reviews to inform evidence-based decisions about drugs that would be available to Medicaid recipients. The Project is coordinated by the Center for Evidence-based Policy (CEbP) at Oregon Health & Science University (OHSU), and the systematic reviews are undertaken by the Evidence-based Practice Centers (EPCs) at OHSU and at the University of North Carolina. The reviews adhere to high standards for comparative effectiveness reviews. Because the investigators have direct, regular communication with policy-makers, the reports have direct impact on policy and decision-making, unlike many systematic reviews. The Project was an innovator of methods to involve stakeholders and continues to develop its methods in conducting reviews that are highly relevant to policy-makers. The methods used for selecting topics, developing key questions, searching, determining eligibility of studies, assessing study quality, conducting qualitative and quantitative syntheses, rating the strength of evidence, and summarizing findings are described. In addition, our on-going interactions with the policy-makers that use the reports are described.

Simulation evaluation of statistical properties of methods for indirect and mixed treatment comparisons

BACKGROUND

Indirect treatment comparison (ITC) and mixed treatment comparisons (MTC) have been increasingly used in network meta-analyses. This simulation study comprehensively investigated statistical properties and performances of commonly used ITC and MTC methods, including simple ITC (the Bucher method), frequentist and Bayesian MTC methods.

METHODS

A simple network of three sets of two-arm trials with a closed loop was simulated. Different simulation scenarios were based on different number of trials, assumed treatment effects, extent of heterogeneity, bias and inconsistency. The performance of the ITC and MTC methods was measured by the type I error, statistical power, observed bias and mean squared error (MSE).

RESULTS

When there are no biases in primary studies, all ITC and MTC methods investigated are on average unbiased. Depending on the extent and direction of biases in different sets of studies, ITC and MTC methods may be more or less biased than direct treatment comparisons (DTC). Of the methods investigated, the simple ITC method has the largest mean squared error (MSE). The DTC is superior to the ITC in terms of statistical power and MSE. Under the simulated circumstances in which there are no systematic biases and inconsistencies, the performances of MTC methods are generally better than the performance of the corresponding DTC methods. For inconsistency detection in network meta-analysis, the methods evaluated are on average unbiased. The statistical power of commonly used methods for detecting inconsistency is very low.

CONCLUSIONS

The available methods for indirect and mixed treatment comparisons have different advantages and limitations, depending on whether data analysed satisfies underlying assumptions. To choose the most valid statistical methods for research synthesis, an appropriate assessment of primary studies included in evidence network is required.

Indirect and mixed-treatment comparison, network, or multiple-treatments meta-analysis: many names, many benefits, many concerns for the next generation evidence synthesis tool

The ever increasing number of alternative treatment options and the plethora of clinical trials have put systematic reviews and meta-analysis under a new perspective by emphasizing the need to make inferences about competing treatments for the same condition. The statistical component in reviews that compare multiple interventions, network meta-analysis, is the next generation evidence synthesis toolkit which, when properly applied, can serve decision-making better than the established pairwise meta-analysis. The criticism and enthusiasm for network meta-analysis echo those that greeted the advent of simple meta-analysis. The main criticism is associated with the difficulty in evaluating the assumption underlying the statistical synthesis of direct and indirect evidence. In the present article, the assumption of the network meta-analysis are presented using various formulations, the statistical and nonstatistical methodological considerations are elucidated, and the progress achieved in this field is summarized. Throughout, focus is put on highlighting the analogy between the concerns and difficulties that the scientific community had some time ago when advancing from individual trials to their quantitative synthesis via meta-analysis and those currently expressed about the transition from head-to-head meta-analyses to network meta-analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Indirect comparisons of new oral anticoagulant drugs for efficacy and safety when used for stroke prevention in atrial fibrillation

OBJECTIVES

This study sought to perform an indirect comparison analysis of dabigatran etexilate (2 doses), rivaroxaban, and apixaban for their relative efficacy and safety against each other.

BACKGROUND

Data for warfarin compared against the new oral anticoagulants (OACs) in large phase III clinical trials of stroke prevention in atrial fibrillation (AF) are now available for the oral direct thrombin inhibitor, dabigatran etexilate, in 2 doses (150 mg twice daily [BID], 110 mg BID), and the oral Factor Xa inhibitors, rivaroxaban and apixaban. A "head-to-head" direct comparison of drugs is the standard method for comparing different treatments, but in the absence of such head-to-head direct comparisons, another alternative to assess the relative effect of different treatment interventions would be to perform indirect comparisons, using a common comparator. Nonetheless, any inter-trial comparison is always fraught with major difficulties, and an indirect comparison analysis has many limitations, especially with the inter-trial population differences and thus, should not be overinterpreted.

METHODS

Indirect comparison analysis was performed using data from the published trials.

RESULTS

There was a significantly lower risk of stroke and systemic embolism (by 26%) for dabigatran (150 mg BID) compared with rivaroxaban, as well as hemorrhagic stroke and nondisabling stroke. There were no significant differences for apixaban versus dabigatran (both doses) or rivaroxaban; or rivaroxaban versus dabigatran 110 mg BID in preventing stroke and systemic embolism. For ischemic stroke, there were no significant differences between the new OACs. Major bleeding was significantly lower with apixaban compared with dabigatran 150 mg BID (by 26%) and rivaroxaban (by 34%), but not significantly different from dabigatran 110 mg BID. There were no significant differences between apixaban and dabigatran 110 mg BID in safety endpoints. Apixaban also had lower major or clinically relevant bleeding (by 34%) compared with rivaroxaban. When compared with rivaroxaban, dabigatran 110 mg BID was associated with less major bleeding (by 23%) and intracranial bleeding (by 54%). There were no significant differences in myocardial infarction events between the dabigatran (both doses) and apixaban.

CONCLUSIONS

Notwithstanding the limitations of an indirect comparison study, we found no profound significant differences in efficacy between apixaban and dabigatran etexilate (both doses) or rivaroxaban. Dabigatran 150 mg BID was superior to rivaroxaban for some efficacy endpoints, whereas major bleeding was significantly lower with dabigatran 110 mg BID or apixaban. Only a head-to-head direct comparison of the different new OACs would fully answer the question of efficacy/safety differences between the new drugs for stroke prevention in AF.

Treating pneumonia in critical care in the United Kingdom following failure of initial antibiotic: a cost-utility analysis comparing meropenem with piperacillin/tazobactam

BACKGROUND

Treating patients admitted to critical care with severe pneumonia requires timely intervention with an effective antibiotic. This reduces the risk of dying of pneumonia and minimises complications associated with a prolonged stay in critical care.

OBJECTIVE

To compare the cost-effectiveness of meropenem 1 g/8 h with piperacillin/tazobactam 4.5 g/8 h for treating pneumonia in UK critical care.

METHODS

A Markov model was built to estimate lifetime costs and quality-adjusted life years (QALYs) of using meropenem versus piperacillin/tazobactam to treat severe pneumonia. Estimates of effectiveness, utility weights and costs were obtained from published sources. Probabilistic sensitivity analysis was conducted to address uncertainty in the model results.

RESULTS

Cost of treating a patient with severe pneumonia was estimated as £19,026 with meropenem and £19,978 with piperacillin/tazobactam, respectively. QALYs gained were 4.768 with meropenem and 4.654 with piperacillin/tazobactam. Probabilistic sensitivity analysis showed meropenem to be consistently less costly and more effective than piperacillin/tazobactam.

CONCLUSION

The additional efficacy of meropenem translates into more patients surviving critical care and leaving this high-cost service more quickly than if they had been treated with piperacillin/tazobactam. As meropenem is more effective and less expensive than piperacillin/tazobactam at treating patients with severe pneumonia, it is the dominant treatment option.

Economic evaluation of duloxetine as a first-line treatment for painful diabetic peripheral neuropathy in Mexico

OBJECTIVE

To perform an economic evaluation of duloxetine, pregabalin, and both branded and generic gabapentin for managing pain in patients with painful diabetic peripheral neuropathy (PDPN) in Mexico.

RESEARCH DESIGN AND METHODS

The analysis was conducted using a 3-month decision model, which compares duloxetine 60 mg once daily (DUL), pregabalin 150 mg twice daily (PGB), and gabapentin 600 mg three-times daily (GBP) for PDPN patients with moderate-to-severe pain. A systematic review was performed and placebo-adjusted risk ratios for achieving good pain relief (GPR), adverse events (AE), and withdrawal owing to intolerable AE were calculated. Direct medical costs included drug acquisition and additional visits due to lack of efficacy (poor pain relief) or intolerable AE. Unit costs were taken from local sources. Adherence rates were used to estimate the expected drug costs. All costs are expressed in 2010 Mexican Pesos (MXN). Utility values drawn from published literature were applied to health states. The proportion of patients with GPR and quality-adjusted life years (QALY) were assessed.

RESULTS

Branded-GBP was dominated by all the other options. PGB was more costly and less effective than DUL. Compared with branded-GBP and PGB, DUL led to savings of 1.01 and 1.74 million MXN (per 1000 patients). The incremental cost per QALY gained with DUL used instead of generic-GBP was $102 433 MXN. This amount is slightly lower than the estimated gross domestic product per capita in Mexico for 2010. During a second-order Monte Carlo simulation, DUL had the highest probability of being cost-effective (61%), followed by generic-GBP (25%) and PGB (14%).

LIMITATIONS

Study limitations include a short timeframe and using data from different dosage schemes for GBP and PGB.

CONCLUSIONS

This study suggests that DUL provides overall savings and better health outcomes compared with branded-GBP and PGB. Administering DUL rather than generic-GBP is a cost-effective intervention to manage PDPN in Mexico.