David Moher and colleagues introduce PRISMA, an update of the QUOROM guidelines for reporting systematic reviews and meta-analyses

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Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement

Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field,1,2 and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research,3 and some health care journals are moving in this direction.4 As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews.

Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in 4 leading medical journals in 1985 and 1986 and found that none met all 8 explicit scientific criteria, such as a quality assessment of included studies.5 In 1987, Sacks and colleagues6 evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in 6 domains. Reporting was generally poor; between 1 and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement.7

In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials.8 In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1).



Box 1

Conceptual issues in the evolution from QUOROM to PRISMA

Preferred reporting items for systematic reviews and meta-analyses: the PRISMA Statement.

Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews . Main outcome measure: Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision. Results: In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias. Conclusions: A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution. Key messages Systematic reviews of randomised trials are the best strategy for appraising evidence; however, the findings of some meta-analyses were later contradicted by large trials Funnel plots, plots of the trials9 effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials Funnel plot asymmetry was found in 38% of meta-analyses published in leading general medicine journals and in 13% of reviews from the Cochrane Database of Systematic Reviews Critical examination of systematic reviews for publication and related biases should be considered a routine procedure

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Bias in meta-analysis detected by a simple, graphical test

Systematic review and meta-analysis

Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement

The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for Reporting Observational Studies Much biomedical research is observational. The reporting of such research is often inadequate, which hampers the assessment of its strengths and weaknesses and of a study's generalisability. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Initiative developed recommendations on what should be included in an accurate and complete report of an observational study. We defined the scope of the recommendations to cover three main study designs: cohort, case-control, and cross-sectional studies. We convened a 2-day workshop in September 2004, with methodologists, researchers, and journal editors to draft a checklist of items. This list was subsequently revised during several meetings of the coordinating group and in email discussions with the larger group of STROBE contributors, taking into account empirical evidence and methodological considerations. The workshop and the subsequent iterative process of consultation and revision resulted in a checklist of 22 items (the STROBE Statement) that relate to the title, , introduction, methods, results, and discussion sections of articles. 18 items are common to all three study designs and four are specific for cohort, case-control, or cross-sectional studies. A detailed Explanation and Elaboration document is published separately and is freely available on the Web sites of PLoS Medicine, Annals of Internal Medicine, and Epidemiology. We hope that the STROBE Statement will contribute to improving the quality of reporting of observational studies.

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Strobe bi̇ldi̇ri̇mi̇: epi̇demi̇yoloji̇de gözlemsel araştirma raporu yaziminin güçlendi̇ri̇lmesi̇ i̇çi̇n bi̇r rehber

A noninferiority trial seeks to determine, whether a new intervention is not inferior to a reference intervention within a prespecified noninferiority interval (-Delta to 0) for the primary outcome. An equivalence trial aims to determine whether two interventions have a similar effect within a prespecified interval (-Delta to +Delta). These trials are controversial and difficult to grasp and very often poorly reported and conducted. Any claims regarding efficacy of new treatments, based on these trials, should be interpreted with caution, and it should be noted that Delta is often far too large to be clinically meaningful.

[Noninferiority and equivalence randomized trials: lessons and reservations--secondary publication].

This chapter argues two evidence-based conclusions: not only are psychiatric drugs dramatically overprescribed and overvalued but the harms they unleash completely overwhelm any benefits accrued. While accepting numerous reasons for our current prescribing epidemic, this chapter focuses on the manipulation of most placebo controlled trials, the systematic underreporting of drug harms, the industry-led misrepresentation of drug safety and efficacy and the medical denial of the substantial role withdrawal and abstinence symptoms play in convincing patients to stay on drugs. This chapter concludes that a thorough and independent review of the evidence base reveals that psychiatric drugs, apart from calming some people down when taken short term, “have failed to deliver what patients want, which is to work specifically for specific mental or emotional problems.” Since mental illness is rarely chronic and lifelong, it argues there is no scientific justification for the widespread lifelong use of psychiatric drugs. If we are to restore balance, and reverse these harms, a total reappraisal of what the evidence teaches must be translated into reformed prescribing guidelines.

Psychopharmacology Is Not Evidence-Based Medicine

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Erratum: Impact of allocation concealment on conclusions drawn from meta-analyses of randomized trials (International Journal of Epidemiology) (2007) vol. 36 (847-857))

Peter C Gøtzsche

Papers

Strobe bi̇ldi̇ri̇mi̇: epi̇demi̇yoloji̇de gözlemsel araştirma raporu yaziminin güçlendi̇ri̇lmesi̇ i̇çi̇n bi̇r rehber

[Noninferiority and equivalence randomized trials: lessons and reservations--secondary publication].

Psychopharmacology Is Not Evidence-Based Medicine

Erratum: Impact of allocation concealment on conclusions drawn from meta-analyses of randomized trials (International Journal of Epidemiology) (2007) vol. 36 (847-857))

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