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.

Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice? 

Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis.

Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4

Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted?

A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …

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Measuring inconsistency in meta-analyses

Systematic review and meta-analysis

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

Consumers and patients are increasingly demanding an active role in health-care access and quality, and associations and pressure groups are interacting directly with national health services and with researchers, doctors and scientific or professional societies. This article describes an Italian project aimed at creating a partnership among lay people, patients associations and the scientific/medical community. In Italy, consumers are generally passive recipients of health information from various sources: doctors and health-care professionals, the health system, media, web and parents or peers. This information is often contradictory and non-evidence-based, leading to misunderstandings and confusion. The Di Bella case, the outcry about an alleged new cure for autism, and the increasing number of health awareness campaigns are all clear examples of the lack of an evidence-based culture among Italian consumers and patients associations (see Box 1). To cope with this, lay people must learn how to develop their scientific literacy, becoming familiar with clinical and epidemiological research and acquiring instruments to critically appraise and understand health information. Although these activities are in their infancy in Italy, there are some good examples of empowerment efforts (see Box 2). The number of consumer and patients associations is steadily growing: a survey in 2003 by the Italian National Statistical Institute identified about 21 000 non-profit organizations across the country, a 50% increase compared with a 1997 survey. These organizations cover a wide spectrum of activities corresponding to a broad definition of health, including psychosocial support and direct services, and the findings confirm the deeply rooted Italian tradition of mutual aid in the health-care field. In the last 10 years, consumers and patients associations have extended their interventions from self-help and care to advocacy, including important efforts to convey more information to the public, and organize awareness raising campaigns. In common with other European and American countries, patients federations are emerging in Italy to boost the impact of individual organizations. Some now lobby at local, national and international level, drawing health authorities attention to the need for improvement in a given area. This has led to the introduction of patients charters and the mandatory presence of lay representatives on local ethics committees, yet the medical and scientific community still fails to see patients and consumer groups as partners with equal rights and weight . Consumers, patients and their associations, on the other hand, often lack doi: 10.1111/j.1369-7625.2007.00444.x

PartecipaSalute, an Italian project to involve lay people, patients' associations and scientific-medical representatives in the health debate.

/pdf/preferred-reporting-items-of-systematic-review-and-meta-f3w9ldpp4v.pdf

Preferred reporting items of systematic review and meta-analyses: the PRISMA statement

The widespread implementation of rationing and priority-setting policies in health care opposes the stochastic practice of medicine induced by professional uncertainty and professional vested interests in market-oriented clinical environments. It also clashes with consumers' overly optimistic and "mythical" view of the effectiveness of medicine, which is bound to support a potentially unlimited provision of health services. Thus, for consumers and society at large, it is necessary to create conditions favorable for a more conscious demand of evidence-based health care. In pursuit of this goal, we suggest the adoption of a community-oriented strategy based upon delivery of information to the public in order a) to generate greater awareness ("healthy skepticism") among consumers, through disclosure of data on the true effectiveness of health care interventions and on the existing variation in their utilization, and b) to provide tools to empower consumers in dealing better with both the uncertainty in their own individual patient-physician relationships and with the health policy issues to be faced in the future. Such a community-oriented strategy could also reinforce and support, through the generation of a "bottom-up" pressure from consumers toward physicians, a wider adoption of evidence-based interventions by health care professionals. This paper, using data from surveys on public opinions and attitudes toward the practice of medicine, focuses on how consumer demand for more evidence-based medical practice can be promoted.

Promoting consumers' demand for evidence-based medicine.

Selective decontamination of digestive tract.

https://www.archives-pmr.org/article/S0003-9993(00)47304-1/pdf

Alessandro Liberati

Papers

PartecipaSalute, an Italian project to involve lay people, patients' associations and scientific-medical representatives in the health debate.

Preferred reporting items of systematic review and meta-analyses: the PRISMA statement

Promoting consumers' demand for evidence-based medicine.

Selective decontamination of digestive tract.

Functional status in patients with spinal cord injury : A new standardized measurement scale