Meta-analysis: Methods, strengths, weaknesses, and political uses

Research encouraging off-label use of quetiapine: A systematic meta-epidemiological analysis

BACKGROUND

Researchers often conduct small studies on testing a drug's efficacy in off-label indications. If positive results from these exploratory studies are not followed up by larger, randomized, double-blinded trials, physicians cannot be sure of a drug's clinical value. This may lead to off-label prescriptions of ineffective treatments. We aim to describe the way clinical studies fostered off-label prescription of the antipsychotic drug quetiapine (Seroquel).

METHODS

In this systematic meta-epidemiological analysis, we searched EMBASE, MEDLINE, Cochrane CENTRAL and PsycINFO databases and included clinical studies testing quetiapine for unapproved indications between May 1995 and May 2022. We then assessed the frequency with which publications providing low-level evidence suggesting efficacy of quetiapine for off-label indications was not followed up by large, randomized and double-blinded trials within 5 years.

RESULTS

In total, 176 published studies were identified that reported potential efficacy of quetiapine in at least 26 indications. Between 2000 and 2007, publication of exploratory studies suggesting promise for off-label indications rapidly outpaced publication of confirmatory trials. In the 24 indications with a minimum of 5 years of follow-up from the first positive exploratory study, 19 (79%) were not followed up with large confirmatory trials within 5 years. At least nine clinical practice guidelines recommend the use of quetiapine for seven off-label indications in which published confirmatory evidence is lacking.

CONCLUSION

Many small, post-approval studies suggested the promise of quetiapine for numerous off-label indications. These findings generally went unconfirmed in large, blinded, randomized trials years after first being published. The imbalance of exploratory and confirmatory studies likely encourages ineffective off-label treatment.

Solid-liquid separation of digestate from biogas plants: A systematic review of the techniques' performance

Digestate processing is a strategy to improve the management of digestate from biogas plants. Solid-liquid separation is usually the primary step and can be followed by advanced treatments of the fractions. The knowledge about the performance of the separators and the quality of the fractions is scattered because of many available techniques and large variability in digestate characteristics. We performed a systematic review and found 175 observations of full-scale solid-liquid separation of digestate. We identified 4 separator groups, 4 digestate classes based on substrate, and distinguished whether chemical conditioners were used. We confirmed the hypothesis that the dominant substrate can affect the efficiency of the digestate separation. Furthermore, the results showed that centrifuges separated significantly more dry matter and total P than screw presses. Use of chemical conditioners in combination with a centrifuge lowered the dry matter concentration in the liquid fraction by 30%. Screw presses consumed 4.5 times less energy than centrifuges and delivered 3.3 tonne ammonium N in the liquid fraction and 0.3 tonne total P in the solid fraction using 1 MWh. The results can provide data for systems analyses of biogas solutions and can support practitioners when choosing among full-scale separator techniques depending on the digestate type. In a broader perspective, this work contributes to the continuous improvement of biogas plants operations and to their role as nutrients recovery sites.

The Effects of Pharmacological Treatment of Nightmares: A Systematic Literature Review and Meta-Analysis of Placebo-Controlled, Randomized Clinical Trials

Nightmares are highly prevalent and distressing for the sufferer, which underlines the need for well-documented treatments. A comprehensive literature review and meta-analysis of the effects of different pharmacological placebo-controlled randomized clinical trials, covering the period up to 1 December 2022, was performed. Searches were conducted in PubMed, Embase, Web of Science, PsychInfo, Cinahl, and Google Scholar, resulting in the identification of 1762 articles, of which 14 met the inclusion criteria: pharmacological intervention of nightmares, based on a placebo-controlled randomized trial published in a European language, reporting outcomes either/or in terms of nightmare frequency, nightmare distress, or nightmare intensity, and reporting sufficient information enabling calculation of effect sizes. Most studies involved the effect of the α1-adrenergic antagonist prazosin in samples of veterans or soldiers suffering from posttraumatic stress disorder. Other medications used were hydroxyzine, clonazepam, cyproheptadine, nabilone, and doxazosin. The vast majority of studies were conducted in the USA. The studies comprised a total of 830 participants. The Clinician-Administered PTSD Scale was the most frequently used outcome measure. The results showed an overall effect size of Hedges' g = 0.50 (0.42 after adjustment for publication bias). The synthetic cannabinoid nabilone (one study) showed the highest effect size (g = 1.86), followed by the histamine H1-antagonist hydroxyzine (one study), and prazosin (10 studies), with effect sizes of g = 1.17 and g = 0.54, respectively. Findings and limitations are discussed, and recommendations for future studies are provided.

Potential Biomarkers for Post-Stroke Cognitive Impairment: A Systematic Review and Meta-Analysis

Stroke is a primary debilitating disease in adults, occurring in 15 million individuals each year and causing high mortality and disability rates. The latest estimate revealed that stroke is currently the second leading cause of death worldwide. Post-stroke cognitive impairment (PSCI), one of the major complications after stroke, is frequently underdiagnosed. However, stroke has been reported to increase the risk of cognitive impairment by at least five to eight times. In recent decades, peripheral blood molecular biomarkers for stroke have emerged as diagnostic, prognostic, and therapeutic targets. In this study, we aimed to evaluate some blood-derived proteins for stroke, especially related to brain damage and cognitive impairments, by conducting a systematic review and meta-analysis and discussing the possibility of these proteins as biomarkers for PSCI. Articles published before 26 July 2021 were searched in PubMed, Embase, the Web of Science, and the Cochrane Library to identify all relevant studies reporting blood biomarkers in patients with stroke. Among 1820 articles, 40 were finally identified for this study. We meta-analyzed eight peripheral biomarker candidates: homocysteine (Hcy), high-density lipoprotein cholesterol (HDL-C), C-reactive protein (CRP), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglyceride (TG), uric acid, and glycated hemoglobin (HbA1c). The Hcy, CRP, TC, and LDL-C levels were significantly higher in patients with PSCI than in the non-PSCI group; however, the HDL-C, TG, uric acid, and HbA1c levels were not different between the two groups. Based on our findings, we suggest the Hcy, CRP, TC, and LDL-C as possible biomarkers in patients with post-stroke cognitive impairment. Thus, certain blood proteins could be suggested as effective biomarkers for PSCI.

Democracy, Culture and Cancer Patients' Willingness to Pay for Healthcare Services: A Meta-analysis

Cancer is one of the leading causes of death globally and expenditure associated with cancer is quite high. Efficient resource allocation needs information on economic evaluations of healthcare interventions. The purposes of the study are to provide a comprehensive overview of cancer patients’ willingness to pay (WTP) for healthcare services and to investigate the influence of democracies, culture dimensions, and other factors on WTP. A meta-analysis was conducted using PubMed, Scopus, and Google Scholar to identify all studies of stated preference approach to estimate cancer patients’ WTP healthcare services. A set of criteria was constructed for selecting relevant studies. A total of 79 studies were related to selection criteria and held sufficient information for the purposes of meta-analysis. A total of 393 estimates of WTP from 79 healthcare valuation studies were pooled to identify the links between WTP and influential factors. The findings suggest that values of benefits in healthcare services are higher in more democratic nations, but they are lower in cultural traits that are stronger indulgence and uncertainty avoidance. Further, the types of cancer matter. Compared to breast cancer, WTP is higher for skin cancer, yet lower for liver cancer and lymphoma. A higher national income and public health expenditure increase WTP for healthcare services, while a higher death rate by cancer leads to lower values of healthcare benefits.

Efficacy of Porcine Epidemic Diarrhea Vaccines: A Systematic Review and Meta-Analysis

Porcine epidemic diarrhea (PED) is a devastating disease that causes considerable economic damage to the global pig industry. Although the causative agent, the porcine epidemic diarrhea virus (PEDV), was identified about a half century ago, there is still much debate on the preventive measures against the disease, especially regarding the PED vaccine. Recent reports on PEDV variants make the vaccination for PEDV more confusing. Therefore, we systematically reviewed published articles on PED and vaccines against the disease and performed a meta-analysis of vaccine efficacy based on the clinical signs, fecal score and survival rates. A total of 299 articles on the efficacy of PED vaccines were found online, and 21 articles were selected that fulfilled all the criteria. A meta-analysis was performed on the 21 articles based on the fecal scores and survival rates. This analysis showed the efficacy of PED vaccines, and no significant differences in the efficacy depending on vaccine type (killed vs. live) or administration route (intramuscular vs. oral) were found. The results from our study suggest that any vaccination against PED is a useful strategy to control the disease regardless of the type of vaccine and administration route.

Epidemiology of preterm birth in Ethiopia: systematic review and meta-analysis

Background

Globally, complications of preterm birth are among the most common cause of neonatal mortality. In Ethiopia, the neonatal mortality reduction is not worthy of attention. Hence, this study reviewed the prevalence of preterm birth and factors associated with preterm birth in Ethiopia.

Methods

The review protocol of this study has been registered in PROSPERO (CRD42017077356). The PRISMA guideline was followed for this review. Studies that assessed the prevalence and/or associated factors of preterm birth in Ethiopia and published from Jan 01, 2009 to Dec 31, 2019 were considered. Studies were searched from the PubMed and Science Direct among medical electronic databases and Google Scholar. Random-effects model was used for detected heterogeneity among studies. Publication bias and sensitivity analysis were assessed. Pooled estimates with its 95% confidence interval were reported using forest plots. The quality of evidence from the review was assessed using GRADE approach.

Results

Twenty-two studies involving a total of 12,279 participants were included. The overall pooled prevalence of preterm birth in Ethiopia was 10.48% (95% CI: 7.98–12.99). Pooled odds ratio showed rural residence (AOR = 2.34, 95% CI: 1.35–4.05), being anemic (AOR = 2.59, 95% CI: 1.85–3.64), < 4 antenatal care visits (AOR = 2.34, 95%CI: 1.73–3.33), pregnancy induced hypertension (AOR = 3.49, 95% CI: 2.45–4.97), prelabor rapture of membrane (AOR = 4.42, 95% CI: 2.28–8.57), antepartum hemorrhage (AOR = 5.02, 95% CI: 2.90–8.68), multiple pregnancies (AOR = 3.89, 95% CI: 2.52–5.99), past adverse birth outcomes (AOR = 3.24, 95% CI: 2.53–4.15) and chronic illness (AOR = 4.89, 95%CI: 3.12–7.66) were associated with increased likelihood of preterm birth. Further, support during pregnancy was associated with reduced occurrence of preterm birth.

Conclusion

The pooled national level prevalence of preterm birth in Ethiopia is high. Socio demographic, nutritional, health care, obstetric and gynecologic, chronic illness and medical conditions, behavioral and lifestyle factors are the major associated factors of preterm birth in Ethiopia. This evidence is graded as low grade. Thus, efforts should be intensified to address reported risk factors to relieve the burden of preterm birth in the study setting, Ethiopia.

Prevalence and associated factors of preterm birth in Ethiopia: systematic review and meta-analysis protocol

INTRODUCTION

Preterm birth (PTB) complications are the leading cause of death among neonates globally. The reduction in neonatal mortality is not remarkable in Ethiopia. Therefore, this review will assess the magnitude and associated factors of PTB in Ethiopia.

METHODS AND ANALYSIS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline will be followed during the systematic review. We will include all observational studies published from 1 January 2009 to 31 December 2019 that examined the level and/or associated factors of any type of PTB among live births in Ethiopia. Inclusion criteria will be all live births, PTB defined as delivery before 37 weeks gestation. The primary outcome will be PTB <37 weeks, and secondary outcomes including PTB <34, <32 and <28 weeks will be analysed. PubMed and Science Direct databases as well as Google search engine and Google Scholar will be searched. The pooled prevalence of preterm and effect size of association for associated factors will be analysed using the Stata software V.14. The heterogeneity between studies will be measured by I2 statistics. A random-effects model will be used to estimate if heterogeneity detected. Publication bias will be assessed using a funnel plot. Subgroup analysis will be sought based on possible characteristics of the studies, specific morbidity (like pre-eclampsia, hypertension), type of PTB (spontaneous or iotrogenic) and quality of study (high-quality or low-risk). Meta-regression will be considered for major covariates (maternal age and maternal body mass index) related to PTB. Forest plots will be used to present the combined estimate with 95% CIs. The quality of evidence of the outcomes will be assessed with the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach.

ETHICS AND DISSEMINATION

No ethical approval is necessary for this systematic review. The findings will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017077356.

Triple Therapy Versus Dual Bronchodilation and Inhaled Corticosteroids/Long-Acting β-Agonists in COPD: Accumulating Evidence from Network Meta-Analyses

Guidelines are mainly based on evidence of well-designed randomized controlled trials (RCTs), but there are limitations to the transferability of conclusions of RCTs to usual care mainly because the patients enrolled in RCTs are selected and not representative of the population encountered in daily practice; moreover, the research environment is substantially different from that of the real world. Because of the scarcity of data generated in large unselected populations in everyday clinical practice, the possibility of using meta-analyses can be considered. Recently, several meta-analyses have attempted to clarify the role of triple therapy containing a long-acting β-agonist (LABA), a long-acting muscarinic antagonist (LAMA) and an inhaled corticosteroid (ICS) delivered from a single inhaler in chronic obstructive pulmonary disease (COPD), also considering that there is a big difference in the use of triple therapy between what is recommended by COPD guidelines or strategies and the prescriptive behaviour of clinicians. Taking into account the results of the most recent meta-analyses, we believe that triple therapy provides modest clinical benefit in the general COPD population, but in patients on LABA/LAMA combination therapy, who still experience acute exacerbations of COPD (AECOPDs) and have blood eosinophil counts ≥ 300 cells·μl⁻¹, it is of clinical relevance. On the contrary, adding a LAMA to an ICS/LABA combination elicits relevant clinical benefit in the general COPD population, supporting the role of dual bronchodilation therapy for the treatment of COPD. The quantitative synthesis of the currently available clinical evidence seems to suggest that, in patients with COPD already on ICS/LABA combination, the therapy can be improved without an increase of cardiovascular severe adverse events (SAEs) when a LAMA is added to the combination.

Guidelines on How to Perform a Meta-Analysis in Spine Surgery: Strengths and Weaknesses of Design

There are many questions in the literature that remain unanswered due to the paucity of available subjects or the large sample size needed to detect a difference. A meta-analysis consists of integrating together data from multiple studies into one larger data set in order to increase the subject size and power of a paper. In essence, it is a systematic review in which one uses statistical methods to summarize the results of these studies. It is important that a meta-analysis be performed in a systematic and orderly manner with the assistance of a statistician. When carried out correctly, these studies serve as powerful tools to help us better address our knowledge. Because of their complexity, they are prone to bias at multiple levels. This article will discuss the steps involved in performing a meta-analysis, select good studies, as well as explain the statistics conducted in these studies. Furthermore, we will discuss examples from the literature that demonstrate a good meta-analysis.

Efficacy and safety profile of xanthines in COPD: a network meta-analysis

Theophylline can still have a role in the management of stable chronic obstructive pulmonary disease (COPD), but its use remains controversial, mainly due to its narrow therapeutic window. Doxofylline, another xanthine, is an effective bronchodilator and displays a better safety profile than theophylline. Therefore, we performed a quantitative synthesis to compare the efficacy and safety profile of different xanthines in COPD.The primary end-point of this meta-analysis was the impact of xanthines on lung function. In addition, we assessed the risk of adverse events by normalising data on safety as a function of person-weeks. Data obtained from 998 COPD patients were selected from 14 studies and meta-analysed using a network approach.The combined surface under the cumulative ranking curve (SUCRA) analysis of efficacy (change from baseline in forced expiratory volume in 1 s) and safety (risk of adverse events) showed that doxofylline was superior to aminophylline (comparable efficacy and significantly better safety), bamiphylline (significantly better efficacy and comparable safety), and theophylline (comparable efficacy and significantly better safety).Considering the overall efficacy/safety profile of the investigated agents, the results of this quantitative synthesis suggest that doxofylline seems to be the best xanthine for the treatment of COPD.

Impact of doxofylline in COPD: A pairwise meta-analysis

Doxofylline is an effective bronchodilator for relieving airway obstruction in patients with asthma or chronic obstructive pulmonary disease (COPD), and displays a better safety profile with respect to theophylline. Herein, we performed a pairwise meta-analysis of the currently available data to provide consistent and homogeneous findings on the impact of this xanthine in COPD patients. Results obtained from 820 patients were selected from 20 clinical trials. Meta-regression was performed to examine the source of heterogeneity between-studies and identify potential confounder covariates. The quality of the evidence was assessed by the GRADE system. Doxofylline induced a significant (P < 0.001) increase in forced expiratory volume in 1 s (FEV₁) of 8.20% (95%CI 4.00-12.41; I² 93%) and 317 ml (95%CI 19-439; I² 87%) compared with baseline. The total administered dose of doxofylline significantly (P < 0.001) interacted with the size of the effect estimates detected for FEV₁. Doxofylline induced a significant (P < 0.001), although moderate, increase in adverse events (AEs) frequency (proportion 0.03, 95%CI 0.02-0.04; I² 88%), but only epigastralgia, nausea, dyspepsia and headache were statistically significant (P < 0.05). The GRADE analysis indicated high quality of evidence (++++) for the impact of doxofylline on FEV₁, and moderate quality of evidence (+++) for the safety profile in COPD patients. Doxofylline is an effective and safe medicine when administered to patients with COPD and can be considered as an alternative to theophylline.

Prevalence of retinopathy of prematurity in Iran: a systematic review and Meta-analysis

AIM

To estimate overall prevalence of retinopathy of prematurity (ROP) in Iran using a systematic review and Meta-analysis.

METHODS

A systematic review and Meta-analysis was performed of all published studies pertaining to prevalence of ROP using international and national electronic databases (ISI Web of Sciences, PubMed, Scopus, Google Scholar, SID, MagIran, and IranMedex) from their inception until May 2016 with standard keywords. Begg and Egger tests were used to examine the publication bias and Cochran test and I² statistics were used to evaluate the statistical heterogeneity. Pooled estimate of the prevalence of ROP were calculated using random effects Meta-analysis.

RESULTS

The publication bias assumption was rejected by Egger tests with P-value equal to 0.024. The results of Cochran test and I² statistics revealed substantial heterogeneity (Q=1099.02, df=25, I²=97.7%, P=0.001). The overall prevalence of ROP using the random effect model in Iran was 26.1% (95% CI: 20.3%-31.8%).

CONCLUSION

The prevalence of ROP is relatively high in Iran. Low birth weight and gestational age are significant risk factors for the disease. Improved care, including oxygen delivery and monitoring, for preterm babies in all facility settings would reduce the number of babies affected with ROP.

The International College of Neuropsychopharmacology (CINP) Treatment Guidelines for Bipolar Disorder in Adults (CINP-BD-2017), Part 1: Background and Methods of the Development of Guidelines

BACKGROUND

This paper includes a short description of the important clinical aspects of Bipolar Disorder with emphasis on issues that are important for the therapeutic considerations, including mixed and psychotic features, predominant polarity, and rapid cycling as well as comorbidity.

METHODS

The workgroup performed a review and critical analysis of the literature concerning grading methods and methods for the development of guidelines.

RESULTS

The workgroup arrived at a consensus to base the development of the guideline on randomized controlled trials and related meta-analyses alone in order to follow a strict evidence-based approach. A critical analysis of the existing methods for the grading of treatment options was followed by the development of a new grading method to arrive at efficacy and recommendation levels after the analysis of 32 distinct scenarios of available data for a given treatment option.

CONCLUSION

The current paper reports details on the design, method, and process for the development of CINP guidelines for the treatment of Bipolar Disorder. The rationale and the method with which all data and opinions are combined in order to produce an evidence-based operationalized but also user-friendly guideline and a specific algorithm are described in detail in this paper.

Predicting Crashes Using Traffic Offences. A Meta-Analysis that Examines Potential Bias between Self-Report and Archival Data

Background

Traffic offences have been considered an important predictor of crash involvement, and have often been used as a proxy safety variable for crashes. However the association between crashes and offences has never been meta-analysed and the population effect size never established. Research is yet to determine the extent to which this relationship may be spuriously inflated through systematic measurement error, with obvious implications for researchers endeavouring to accurately identify salient factors predictive of crashes.

Methodology and Principal Findings

Studies yielding a correlation between crashes and traffic offences were collated and a meta-analysis of 144 effects drawn from 99 road safety studies conducted. Potential impact of factors such as age, time period, crash and offence rates, crash severity and data type, sourced from either self-report surveys or archival records, were considered and discussed. After weighting for sample size, an average correlation of r = .18 was observed over the mean time period of 3.2 years. Evidence emerged suggesting the strength of this correlation is decreasing over time. Stronger correlations between crashes and offences were generally found in studies involving younger drivers. Consistent with common method variance effects, a within country analysis found stronger effect sizes in self-reported data even controlling for crash mean.

Significance

The effectiveness of traffic offences as a proxy for crashes may be limited. Inclusion of elements such as independently validated crash and offence histories or accurate measures of exposure to the road would facilitate a better understanding of the factors that influence crash involvement.

Incidence and prevalence of Vibrio parahaemolyticus in seafood: a systematic review and meta-analysis

Vibrio parahaemolyticus is an important seafood borne human pathogen worldwide due to it occurrence, prevalence and ability to cause gastrointestinal infections. This current study aim at investigating the incidence and prevalence of V. parahaemolyticus in seafood using systematic review-meta-analysis by exploring heterogeneity among primary studies. A comprehensive systematic review and meta-analysis of peer reviewed primary studies reported between 2003 and 2015 for the occurrence and prevalence of V. parahaemolyticus in seafood was conducted using “isolation”, “detection”, “prevalence”, “incidence”, “occurrence” or “enumeration” and V. parahaemolyticus as search algorithms in Web of Science (Science Direct) and ProQuest of electronic bibliographic databases. Data extracted from the primary studies were then analyzed with fixed effect meta-analysis model for effect rate to explore heterogeneity between the primary studies. Publication bias was evaluated using funnel plot. A total of 10,819 articles were retrieved from the data bases of which 48 studies met inclusion criteria. V. parahaemolyticus could only be isolated from 2761 (47.5 %) samples of 5811 seafood investigated. The result of this study shows that incidence of V. parahaemolyticus was more prevalent in oysters with overall prevalence rate of 63.4 % (95 % CI 0.592–0.674) than other seafood. Overall prevalence rate of clams was 52.9 % (95 % CI 0.490–0.568); fish 51.0 % (95 % CI 0.476–0.544); shrimps 48.3 % (95 % CI 0.454–0.512) and mussels, scallop and periwinkle: 28.0 % (95 % CI 0.255–0.307). High heterogeneity (p value <0.001; I² = 95.291) was observed mussel compared to oysters (I² = 91.024). It could be observed from this study that oysters harbor V. parahaemolyticus based on the prevalence rate than other seafood investigated. The occurrence and prevalence of V. parahaemolyticus is of public health importance, hence, more studies involving seafood such as mussels need to be investigated.

Occurrence and prevalence of Cronobacter spp. in plant and animal derived food sources: a systematic review and meta-analysis

Cronobacter species are motile, non-spore forming, Gram negative emerging opportunistic pathogens mostly associated with bacteremia, meningitis, septicemia, brain abscesses and necrotizing enterocolitis in infected neonates, infants and immunocompromised adults. Members of the genus Cronobacter are previously associated with powdered infant formula although the main reservoir and routes of contamination are yet to be ascertained. This study therefore aim to summarize occurrence and prevalence of Cronobacter spp. from different food related sources. A retrospective systematic review and meta-analysis of peer reviewed primary studies reported between 2008 and 2014 for the occurrence and prevalence of Cronobacter spp. in animal and plant related sources was conducted using “Cronobacter isolation”, “Cronobacter detection” and “Cronobacter enumeration” as search terms in the following databases: Web of Science (Science Direct) and ProQuest. Data extracted from the primary studies were then analyzed with meta-analysis techniques for effect rate and fixed effects was used to explore heterogeneity between the sources. Publication bias was evaluated using funnel plot. A total of 916 articles were retrieved from the data bases of which 28 articles met inclusion criteria. Cronobacter spp. could only be isolated from 103 (5.7 %) samples of animal related food while 123 (19 %) samples of plant related food samples harbors the bacteria. The result of this study shows that occurrence of Cronobacter was more prevalent in plant related sources with overall prevalence rate of 20.1 % (95 % CI 0.168–0.238) than animal originated sources with overall prevalence rate of 8 % (95 % CI 0.066–0.096). High heterogeneity (I² = 84) was observed mostly in plant related sources such as herbs, spices and vegetables compared to animal related sources (I² = 82). It could be observed from this study that plant related sources serve as reservoir and contamination routes of Cronobacter spp.

Sparse meta-analysis with high-dimensional data

Meta-analysis plays an important role in summarizing and synthesizing scientific evidence derived from multiple studies. With high-dimensional data, the incorporation of variable selection into meta-analysis improves model interpretation and prediction. Existing variable selection methods require direct access to raw data, which may not be available in practical situations. We propose a new approach, sparse meta-analysis (SMA), in which variable selection for meta-analysis is based solely on summary statistics and the effect sizes of each covariate are allowed to vary among studies. We show that the SMA enjoys the oracle property if the estimated covariance matrix of the parameter estimators from each study is available. We also show that our approach achieves selection consistency and estimation consistency even when summary statistics include only the variance estimators or no variance/covariance information at all. Simulation studies and applications to high-throughput genomics studies demonstrate the usefulness of our approach.

Importance of meta-analysis and practical obstacles in oncological and epidemiological studies: statistics very close but also far!

Studies of epidemiological and prognostic factors are very important for oncology practice. There is a rapidly increasing amount of research and resultant knowledge in the scientific literature. This means that health professionals have major challenges in accessing relevant information and they increasingly require best available evidence to make their clinical decisions. Meta-analyses of prognostic and other epidemiological factors are very practical statistical approaches to define clinically important parameters. However, they also feature many obstacles in terms of data collection, standardization of results from multiple centers, bias, and commentary for intepretation. In this paper, the obstacles of meta-analysis are briefly reviewed, and potential problems with this statistical method are discussed.

Meta-epidemiology

The concept of meta-epidemiology has been introduced with considering the methodological limitations of systematic review for intervention trials. The paradigm of meta-epidemiology has shifted from a statistical method into a new methodology to close gaps between evidence and practice. Main interest of meta-epidemiology is to control potential biases in previous quantitative systematic reviews and draw appropriate evidences for establishing evidence-base guidelines. Nowadays, the network meta-epidemiology was suggested in order to overcome some limitations of meta-epidemiology. To activate meta-epidemiologic studies, implementation of tools for risk of bias and reporting guidelines such as the Consolidated Standards for Reporting Trials (CONSORT) should be done.

Analysis of multiple genetic polymorphisms in aggressive-growing and slow-growing abdominal aortic aneurysms

BACKGROUND

The natural history of abdominal aortic aneurysms (AAAs) suggests that some remain slow in growth rate whereas many develop a more accelerated growth rate and reach a threshold for intervention. We hypothesized that different mechanisms are responsible for AAAs that remain slow growing and never become actionable vs the aggressive AAAs that require intervention and may be reflected by distinct associations with genetic polymorphisms.

METHODS

AAA growth rate was determined from serial imaging data in 168 control and 141 AAA patients with ultrasound or computed tomography imaging studies covering ∼5 years. Genetic polymorphisms all previously reported as showing a significant correlation with AAA with functional effects on the expression or function were determined by analysis of the genomic DNA, including angiotensin 1 receptor (rs5186), interleukin-10 (IL-10; rs1800896), methyl-tetrahydrofolate reductase (rs1801133), low-density lipoprotein receptor-related protein 1 (LRP1; rs1466535), angiotensin-converting enzyme (rs1799752), and several matrix metalloproteinase 9 (MMP-9) single nucleotide polymorphisms.

RESULTS

Of the AAA patients, 81 were classified as slow AAA growth rate (<3.25 mm/y) vs 60 with aggressive AAA growth rate (>3.25 mm/y, those presenting with a rupture, or those with maximal aortic diameter >5.5 cm [male] or >5.0 cm [female]). Discriminating confounds between the groups were identified by logistic regression. Analyses identified MMP-9 p-2502 single nucleotide polymorphism (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.31-0.94; P = .029) as a significant confound discriminating between control vs slow-growth AAA, MMP-9 D165N (OR, 0.49; 95% CI, 0.26-0.95; P = .035) and LRP1 (OR, 4.99; 95% CI, 1.13-22.1; P = .034) between control vs aggressive-growth AAAs, and methyltetrahydrofolate reductase (OR, 2.99; 95% CI, 1.01-8.86; P = .048), MMP-9 p-2502 (OR, 2.19; 95% CI, 1.05-4.58; P = .037), and LRP1 (OR, 4.96; 95% CI, 1.03-23.9; P = .046) as the statistically significant confounds distinguishing slow-growth AAAs vs aggressive-growth AAAs.

CONCLUSIONS

Logistic regression identified different genetic confounds for the slow-growth and aggressive-growth AAAs, indicating a potential for different genetic influences on AAAs of distinct aggressiveness. Future logistic regression studies investigating for potential genetic or clinical confounds for this disease should take into account the growth rate and size of the AAA to better identify confounds likely to be associated with aggressive AAAs likely to require intervention.

Meta-analysis of the use of narrative exposure therapy for the effects of trauma among refugee populations

BACKGROUND

Narrative therapies, especially narrative exposure therapy, are used to treat the effects of trauma in refugees and to prevent psychiatric illness. These methods involve helping the person to tell the story of what happened to them until it no longer elicits anxiety.

METHODS

We reviewed all quantitative studies related to narrative exposure methods for treating trauma or posttraumatic stress disorder in refugees. We focused on studies with sufficient information to calculate effect sizes and statistical power.

RESULTS

We found 7 quantitative studies for which effect size and power could be calculated. The total average effect size for all interventions was 0.63 (medium). The average effect size for studies in which interventions were administered by physicians, adequately trained graduate students, or both was 0.53. The effect size for studies in which the counselors were themselves refugees was 1.02. The 95% confidence intervals for the effect sizes of narrative exposure therapy did not reach below 0.

CONCLUSION

Studies demonstrating the effectiveness of narrative methods have adequate effect sizes and statistical power. Empowering lay counselors to treat their fellow refugees in future studies is warranted.

Metformin and cancer

Type 2 diabetes mellitus is a rising cause of cardiovascular morbidity and mortality. A number of studies have also identified diabetic patients as having increased risk for the development of cancer. Metformin is a widely prescribed antidiabetic drug with an established efficacy coupled with a favorable safety profile and low cost. An increasing number of studies have associated metformin treatment with a decrease of cancer risk. Moreover, metformin has also been associated with improved outcomes in cancer patients. These possible pleiotropic effects of metformin may establish metformin as a cancer prevention and treatment option. However, any favorable effects of metformin on cancer are not always corroborated by clinical trials. Larger studies are expected to better investigate the possible antineoplastic effects of metformin.

Efficacy of pharmacotherapy in bipolar disorder: a report by the WPA section on pharmacopsychiatry

The current statement is a systematic review of the available data concerning the efficacy of medication treatment of bipolar disorder (BP). A systematic MEDLINE search was made concerning the treatment of BP (RCTs) with the names of treatment options as keywords. The search was updated on 10 March 2012. The literature suggests that lithium, first and second generation antipsychotics and valproate and carbamazepine are efficacious in the treatment of acute mania. Quetiapine and the olanzapine-fluoxetine combination are also efficacious for treating bipolar depression. Antidepressants should only be used in combination with an antimanic agent, because they can induce switching to mania/hypomania/mixed states/rapid cycling when utilized as monotherapy. Lithium, olanzapine, quetiapine and aripiprazole are efficacious during the maintenance phase. Lamotrigine is efficacious in the prevention of depression, and it remains to be clarified whether it is also efficacious for mania. There is some evidence on the efficacy of psychosocial interventions as an adjunctive treatment to medication. Electroconvulsive therapy is an option for refractory patients. In acute manic patients who are partial responders to lithium/valproate/carbamazepine, adding an antipsychotic is a reasonable choice. The combination with best data in acute bipolar depression is lithium plus lamotrigine. Patients stabilized on combination treatment might do worse if shifted to monotherapy during maintenance, and patients could benefit with add-on treatment with olanzapine, valproate, an antidepressant, or lamotrigine, depending on the index acute phase. A variety of treatment options for BP are available today, but still unmet needs are huge. Combination therapy may improve the treatment outcome but it also carries more side-effect burden. Further research is necessary as well as the development of better guidelines and algorithms for the step-by-step rational treatment.

Meta-analysis of food safety training on hand hygiene knowledge and attitudes among food handlers

Research has shown that traditional food safety training programs and strategies to promote hand hygiene increases knowledge of the subject. However, very few studies have been conducted to evaluate the impact of food safety training on food handlers' attitudes about good hand hygiene practices. The objective of this meta-analytical study was to assess the extent to which food safety training or intervention strategies increased knowledge of and attitudes about hand hygiene. A systematic review of food safety training articles was conducted. Additional studies were identified from abstracts from food safety conferences and food science education conferences. Search terms included combinations of "food safety," "food hygiene," "training," "education," "hand washing," "hand hygiene," "knowledge," "attitudes," "practices," "behavior," and "food handlers." Only before- and after-training approaches and cohort studies with training (intervention group) and without training (control group) in hand hygiene knowledge and including attitudes in food handlers were evaluated. All pooled analyses were based on a random effects model. Meta-analysis values for nine food safety training and intervention studies on hand hygiene knowledge among food handlers were significantly higher than those of the control (without training), with an effect size (Hedges' g) of 1.284 (95% confidence interval [CI] ∼ 0.830 to 1.738). Meta-analysis of five food safety training and intervention studies in which hand hygiene attitudes and self-reported practices were monitored produced a summary effect size of 0.683 (95% CI ∼ 0.523 to 0.843). Food safety training increased knowledge and improved attitudes about hand hygiene practices. Refresher training and long-term reinforcement of good food handling behaviors may also be beneficial for sustaining good hand washing practices.

What the Tortoise said to Achilles

Practitioners and investigators often view clinical trials from very different perspectives-the former in terms of individuals and the latter in terms of groups. The following whimsical dialogue highlights the philosophical foundations of these contrasting perspectives and illustrates their potential impact on patient care and public policy. The title alludes to a piece by Lewis Carroll regarding Zeno's paradox, purportedly proving that the fleet-footed Achilles cannot outrun the plodding Tortoise in a foot race.

Self-study of values, beliefs, and conflict of interest: the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders

STUDY DESIGN

Observation and survey of values, beliefs, and conflicts of interest.

OBJECTIVE

To study the values, beliefs, and potential conflicts of interest that the Neck Pain Task Force brought to their deliberations.

SUMMARY OF BACKGROUND DATA

Researchers' values and beliefs were studied to uncover areas of divergence and to develop guiding principles to assist decision making.

METHODS

An observer used direct observation and survey of the Neck Pain Task Force, facilitated discussion, and developed a "disclosure tool" to collect information about relationships between researchers, funders, and others with a vested interest in the outcome.

RESULTS

Clinicians and research methodologists brought different imperatives to the research process. Clinicians focused on offering useful advice, whereas methodologists guarded investigative rigor to ensure that evidence actually supported advice. Group conflict did not polarize along "clinical discipline lines." The Advisory Committee had greater impact when given a clear task and time to work as a group. The Neck Pain Task Force agreed on a set of "guiding principles," which became an overarching doctrine to guide their work. The disclosure questionnaires described relationships between Neck Pain Task Force members and other entities that might have had a financial interest in the topic.

CONCLUSION

This study describes a process used to assess values, beliefs, and conflicts of interest among members of a scientific task force, and how this was used to create "guiding principles" to assist the research team in deliberations, particularly when conflict arose. Most members of the Neck Pain Task Force had potential conflicts of interest with various stakeholders, but there was marked diffusion of these potential conflicts and no evidence that any funder or other vested interest stakeholder was likely to have a significant impact on the deliberations or conclusions of the Neck Pain Task Force.

A meta-analysis study of the effect of chilling on prevalence of Salmonella on pig carcasses

In the field of food safety, meta-analysis can be used to combine results of prevalence studies of pathogens at critical stages within the food processing chain so that policy makers can access reliable and concise information on the effectiveness of interventions for controlling and preventing foodborne illnesses in humans. The objective of this work was to demonstrate the applicability of a parametric approach of meta-analysis to the specific case of determining the overall effect of chilling on Salmonella prevalence on pig carcasses. A meta-analysis was performed on each of two parameters measuring effect size for binary outcomes (relative risk and risk difference). Both meta-analyses confirmed that the chilling operation has a significant beneficial effect (P < 0.001) on the reduction of Salmonella prevalence on pig carcasses. Because risk difference is a parameter sensitive to the differences across studies in carcass swab areas and Salmonella detection methods, its meta-analysis highly reflected this heterogeneity (P < 0.001). However, parameterization of relative risk, not being biased by the above sources of variability, did not give rise to heterogeneity among studies and produced a fixed-effects meta-analysis solution, which is deemed more suitable for compilations based on a small number of individual studies (n = 9). Because of the systematic approach of meta-analysis (i.e., individual studies are weighed according to precision) and its reliance for actual data, the output distribution of the relative risk effect size (approximately eN(-0.868,0.166)) merits consideration for inclusion in the chilling stage of quantitative risk assessments modeling the prevalence of this pathogen along the pork production chain.

Albendazole versus praziquantel in the treatment of neurocysticercosis: a meta-analysis of comparative trials

Background

Neurocysticercosis, infection of the brain with larvae of Taenia solium (pork tapeworm), is one of several forms of human cysticercosis caused by this organism. We investigated the role of albendazole and praziquantel in the treatment of patients with parenchymal neurocysticercosis by performing a meta-analysis of comparative trials of their effectiveness and safety.

Methods and Principal Findings

We performed a search in the PubMed database, Cochrane Database of Controlled Trials, and in references of relevant articles. Six studies were included in the meta-analysis. Albendazole was associated with better control of seizures than praziquantel in the pooled data analysis, when the generic inverse variance method was used to combine the incidence of seizure control in the included trials (patients without seizures/[patients×years at risk]) (156 patients in 4 studies, point effect estimate [incidence rate ratio] = 4.94, 95% confidence interval 2.45–9.98). In addition, albendazole was associated with better effectiveness than praziquantel in the total disappearance of cysts (335 patients in 6 studies, random effects model, OR = 2.30, 95% CI 1.06–5.00). There was no difference between albendazole and praziquantel in reduction of cysts, proportion of patients with adverse events, and development of intracranial hypertension due to the administered therapy.

Conclusions

A critical review of the available data from comparative trials suggests that albendazole is more effective than praziquantel regarding clinically important outcomes in patients with neurocysticercosis. Nevertheless, given the relative scarcity of trials, more comparative interventional studies—especially randomized controlled trials—are required to draw a safe conclusion about the best regimen for the treatment of patients with parenchymal neurocysticercosis.

Neurocysticercosis is a parasitic disease caused by the pork tapeworm, Taenia solium, when the larval form of the parasite lodges in the central nervous system. This disease is most commonly found among members of agricultural societies with poor sanitary conditions and economies based on breeding livestock (especially pigs) with low hygiene standards. It is a disease with long history in humans, and the usual therapeutic intervention was surgery until the development of antiparasitic cysticidal agents, the most common being praziquantel and albendazole. T. solium infection can take many different forms in humans, but we concentrated on parenchymal neurocysticercosis with viable cysts. A consensus statement by a panel of experts on the subject supports the use of antiparasitic treatment, but does not indicate either albendazole or praziquantel as the drug of choice for this type of neurocysticercosis, because data from single relevant clinical trials are not conclusive. We conducted a meta-analysis to further evaluate the comparative effectiveness and safety of albendazole and praziquantel for this particular type of neurocysticercosis. The outcomes of our meta-analysis suggest that albendazole is more effective than praziquantel in controlling seizures in affected patients and in leading to the total disappearance of cysts and subsequently cure of patients with neurocysticercosis.

Protecting People With Decisional Impairments and Legal Incapacity Against Biomedical Research Abuse

Ethical and legal principles are provided for reviewing the ethics of recent cases of biomedical research abuse involving persons with decisional impairments or legal incapacity who were unable to understand the risks and benefits of the research to which they were subjected. Research abuse continues to occur despite guidance from the Nuremburg Code, the Declaration of Helsinki, the U.S. Belmont Report, extensive federal regulations governing human participant research, and several professional and disciplinary codes of ethics with which, the authors believe, the majority of researchers comply. Contributing to research abuse are weaknesses in the institutional review board and research ethics board review process; conflicting opinions about applicable ethical principles; mounting evidence of pervasive conflicts of interest; and dubious conflated research and marketing practices involving researchers, pharmaceutical and medical device manufacturers, and government research sponsors and regulatory agencies. Several recommendations are made to correct identifiable weaknesses and failures in the governance of biomedical research.

Schizophrenia, "Just the Facts": what we know in 2008 part 1: overview

For every disorder, there is a set of established findings and accepted constructs upon which further understanding is built. The concept of schizophrenia as a disease entity has been with us for a little more than a century, although descriptions resembling this condition predate this conceptualization. In 1988, for the inaugural issue of Schizophrenia Research, at the invitation of the founding editors, a senior researcher, since deceased (RJ Wyatt) published a summary of generally accepted ideas about the disorder, which he termed "the facts" of schizophrenia. Ten years later, in conjunction with two of the authors (MSK, RT), he compiled a more extensive set of "facts" for the purpose of evaluating conceptual models or theoretical constructs developed to understand the nature of schizophrenia. On the 20th anniversary of this journal, we update and substantially expand our effort to periodically summarize the current body of information about schizophrenia. We compile a body of seventy-seven representative major findings and group them in terms of their specific relevance to schizophrenia -- etiologies, pathophysiology, clinical manifestations, and treatments. We rate each such "fact" on a 0-3 scale for measures of reproducibility, whether primary to schizophrenia, and durability over time. We also pose one or more critical questions with reference to each "fact", answers to which might help better elucidate the meaning of that finding for our understanding of schizophrenia. We intend to follow this paper with the submission to the journal of a series of topic-specific articles, critically reviewing the evidence.

World Psychiatric Association Pharmacopsychiatry Section statement on comparative effectiveness of antipsychotics in the treatment of schizophrenia

Data from two major government-funded studies of comparative antipsychotic effectiveness in schizophrenia contradict the widely prevalent belief that the newer second-generation medications are vastly superior to the older first-generation drugs. This has caused uncertainty among patients, clinicians and policy-makers about the relative utility of first- and second- generation antipsychotic agents in its treatment. To reduce confusion and provide a contextual understanding of the new data, the World Psychiatry Association Section on Pharmacopsychiatry comprehensively reviewed the literature on the comparative effectiveness of different antipsychotic treatments for schizophrenia and developed this update. Utilizing data from the approximately 1,600 randomized controlled trials of antipsychotic treatment in schizophrenia, we applied the two indirect and one direct method to comparing the effectiveness of 62 currently-available antipsychotic agents. The subclasses of 51 first-generation and 11 second-generation antipsychotics were both found to be very heterogeneous, with substantial differences in side-effect profiles among members. Second-generation antipsychotic agents were found to be inconsistently more effective than first-generation agents in alleviating negative, cognitive, and depressive symptoms and had a lower liability to cause tardive dyskinesia; these modest benefits were principally driven by the ability of second-generation antipsychotics to provide equivalent improvement in positive symptoms along with a lower risk of causing extrapyramidal side-effects. Clozapine was found to be more efficacious than other agents in treatment-refractory schizophrenia. There were no consistent differences in efficacy among other second-generation antipsychotic agents; if such differences exist, they are likely small in magnitude. Dosing was found to be a key variable in optimizing effectiveness of both first- and second- generation antipsychotic agents. There was enormous individual variability in antipsychotic response and vulnerability to various adverse effects. In contrast to their relatively similar efficacy in treating positive symptoms, there were substantial differences among both first- and second- generation antipsychotic agents with regard to their propensity to cause extrapyramidal, metabolic and other adverse effects; second-generation agents have a lower liability to cause acute extrapyramidal symptoms and tardive dyskinesia along with a tendency to cause greater metabolic side-effects than first-generation agents. Based on these data about the comparative effectiveness of different antipsychotic treatment options, we summarize elements of current best antipsychotic practice for the treatment of schizophrenia and discuss the role of government and the pharmaceutical industry in obtaining and disseminating information which can facilitate best practice.

Self-study of values, beliefs, and conflict of interest: the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders

STUDY DESIGN

Observation and survey of values, beliefs, and conflicts of interest.

OBJECTIVE

To study the values, beliefs, and potential conflicts of interest that the Neck Pain Task Force brought to their deliberations.

SUMMARY OF BACKGROUND DATA

Researchers' values and beliefs were studied to uncover areas of divergence and to develop guiding principles to assist decision making.

METHODS

An observer used direct observation and survey of the Neck Pain Task Force, facilitated discussion, and developed a "disclosure tool" to collect information about relationships between researchers, funders, and others with a vested interest in the outcome.

RESULTS

Clinicians and research methodologists brought different imperatives to the research process. Clinicians focused on offering useful advice, whereas methodologists guarded investigative rigor to ensure that evidence actually supported advice. Group conflict did not polarize along "clinical discipline lines." The Advisory Committee had greater impact when given a clear task and time to work as a group. The Neck Pain Task Force agreed on a set of "guiding principles," which became an overarching doctrine to guide their work. The disclosure questionnaires described relationships between Neck Pain Task Force members and other entities that might have had a financial interest in the topic.

CONCLUSION

This study describes a process used to assess values, beliefs, and conflicts of interest among members of a scientific task force, and how this was used to create "guiding principles" to assist the research team in deliberations, particularly when conflict arose. Most members of the Neck Pain Task Force had potential conflicts of interest with various stakeholders, but there was marked diffusion of these potential conflicts and no evidence that any funder or other vested interest stakeholder was likely to have a significant impact on the deliberations or conclusions of the Neck Pain Task Force.

A meta-analysis of N-acetylcysteine in contrast-induced nephrotoxicity: unsupervised clustering to resolve heterogeneity

BACKGROUND

Meta-analyses of N-acetylcysteine (NAC) for preventing contrast-induced nephrotoxicity (CIN) have led to disparate conclusions. Here we examine and attempt to resolve the heterogeneity evident among these trials.

METHODS

Two reviewers independently extracted and graded the data. Limiting studies to randomized, controlled trials with adequate outcome data yielded 22 reports with 2746 patients.

RESULTS

Significant heterogeneity was detected among these trials (I2 = 37%; p = 0.04). Meta-regression analysis failed to identify significant sources of heterogeneity. A modified L'Abbé plot that substituted groupwise changes in serum creatinine for nephrotoxicity rates, followed by model-based, unsupervised clustering resolved trials into two distinct, significantly different (p < 0.0001) and homogeneous populations (I2 = 0 and p > 0.5, for both). Cluster 1 studies (n = 18; 2445 patients) showed no benefit (relative risk (RR) = 0.87; 95% confidence interval (CI) 0.68-1.12, p = 0.28), while cluster 2 studies (n = 4; 301 patients) indicated that NAC was highly beneficial (RR = 0.15; 95% CI 0.07-0.33, p < 0.0001). Benefit in cluster 2 was unexpectedly associated with NAC-induced decreases in creatinine from baseline (p = 0.07). Cluster 2 studies were relatively early, small and of lower quality compared with cluster 1 studies (p = 0.01 for the three factors combined). Dialysis use across all studies (five control, eight treatment; p = 0.42) did not suggest that NAC is beneficial.

CONCLUSION

This meta-analysis does not support the efficacy of NAC to prevent CIN.

Basic concepts in meta-analysis: A primer for clinicians

With the expanding volume of medical literature, meta-analysis, a form of systematic review, has become indispensable for clinicians for evidence-based decision making. While the number of meta-analyses has substantially increased during recent years, there are still controversial issues regarding their methodology, interpretation and clinical application. In this review, the basic concepts of meta-analysis have been discussed from a clinician's perspective in order to facilitate its understanding, appraising and applicability in clinical practice. Although randomised controlled trials are the usual source for meta-analysis, observational studies are also being increasingly considered for meta-analysis. Like every other research design, meta-analysis starts with formulating a question, followed by searching for related data, based on predefined criteria and strategies. Inclusion of studies must be carried out with careful consideration of their quality and assessment of homogeneity using graphical means as well as statistical tools such as Q statistics, I(2) statistics and meta-regression. The pooled effect size is commonly calculated using either a 'fixed effect model' or 'random effect model'. Publication bias and other source of bias should be investigated and the impact of potential confounders should be eliminated as required. Given the above-mentioned considerations, meta-analysis can provide a more precise estimate of an effect size to be used in clinical decision making.