STROBE: new standards for reporting observational epidemiology, a chance to improve.

The shortfalls of observational epidemiology in terms of the generation of contradictory and spurious findings have been highlighted by many commentators—perhaps most memorably by pop-science journalist and general practitioner, James Le Fanu, who stated that ‘the simple expedient of closing down most University departments of Epidemiology could both extinguish this endlessly fertile source of anxiety-mongering while simultaneously releasing funds for serious research’. Serious critiques of observational epidemiology have highlighted its vulnerability to confounding, reverse causation, measurement error and selection bias. However, the closure of University departments and the abandonment of observational epidemiology might be premature without first trying some remedial steps. One important step would be to improve the reporting of observational epidemiology studies. Lessons may be learned from the early days of randomized controlled trials where it was obvious that not all trials were equal—some were clearly better done than others and consequently produced more trustworthy results. Exploration of the sources of bias in the conduct of trials identified characteristics that were linked with the validity of estimates of effect sizes, and led to criteria that could be used to improve trial quality and, importantly, should help users to distinguish well conducted from poorly conducted trials. An interesting issue became apparent as more and more energy was put into abstracting data from published trials for systematic reviews—the quality of a trial is often difficult to assess from the published report of its findings. Published reports are not research protocols. Methods sections are often too brief for adequate understanding of how the trial was done. The vagaries of editors anxious to save space for the more exciting findings over the details of what was actually done, make large cuts to methodological detail but this detail is essential in assessing whether the findings are valid or not. With these concerns in mind the CONSORT—CONsolidated Standards Of Reporting Trials—statement was derived. CONSORT has required revisions to take into account reporting of adverse events in trials, non-inferiority and equivalence trials, and has been updated. Moreover, application of CONSORT appears to have improved the quality of reporting of trials. 10,11 In an effort to improve reporting of observational epidemiology studies, the STROBE (STrengthening the Reporting of OBservational studies in Epidemiology) initiative was established in 2004, including several of the people involved in CONSORT. The group will publish its main statement in several international journals simultaneously and a longer explanatory paper giving a detailed rationale will be published in Epidemiology. STROBE decided to limit its initial work to three major designs—cohort, case-control and cross-sectional. This was wise. If the approach proves applicable in practice and improves reporting of the major study designs, its application to other designs such as case series, audits and database studies can be considered in updates. The authors of STROBE state many things that the checklist of 22 items is not. It is not intended to be prescriptive, to regulate terminology, to be used to assess study quality or to guide the planning or design of studies. So what is it actually for? It is meant to assist authors in writing up their work, help editors and reviewers as part of the peer review process, and make it easier for readers to critically appraise published papers. These purposes and some of the items do seem to overlap with assessing study quality as indicated by the similarity of items identified in a systematic review of tools to assess quality and susceptibility to bias. So how successfully have the STROBE group risen to the challenges of the varied nature of observational epidemiology? The effort to be non-prescriptive has resulted in rather general suggestions for authors, some of which will be found in any epidemiology text targeted at Masters students in the first term of their first year. Despite the companion explanatory long paper, the investigator seeking guidance may end up confused. For example the item ‘State the scientific background and rationale for the investigation being reported’ sounds unambiguous but in long-term cohort studies the original rationale may have been understanding the causes of cardiovascular disease but the purpose of the report is study of a quite different condition—say incontinence of urine. The original purpose of the cohort will have a bearing on the types of covariates available for investigation and will illuminate what is feasible for the investigators to attempt in analyses but ultimately the availability of the latter are the important factor. * Corresponding author. London School of Hygiene & Tropical Medicine, Keppel Street, London WCIE 7HT. E-mail: [email protected] 1 Co-Editor IJE and Coordinating Editor, Cochrane Heart Group, LSHTM. 2 Director UK Cochrane Centre, Oxford. Published by Oxford University Press on behalf of the International Epidemiological Association The Author 2007; all rights reserved. Advance Access publication 21 September 2007 International Journal of Epidemiology 2007;36:946–948 doi:10.1093/ije/dym185