Quality Assessment of the Reporting of Cohort Studies before STROBE Statement

Observational studies are not often reported in detail and clear enough, so that assessment of the strengths and weaknesses of these studies is not straightforward. To improve the reporting of observational studies, a checklist of items called ‘Strengthening the Reporting of Observational Studies in Epidemiology’ (STROBE) was developed by some experts in October 2007. The aim of this study was to assess the quality of reporting of observational studies before STROBE statement. We included randomly sixty cohort studies published in six important international journals until October 2007. Then, we used STROBE checklist to assess the strengths and weaknesses of these included studies. On average, more than 81% (95% CI: 77%-87%) of included studies pointed to 43 items of aim of this study. The most reported (100%) items were "scientific background" and "rationale for the investigation" and the less reported (30%) item was “flow chart”. Although, the quality of reported cohort studies’ results was acceptable, the type of study, journal and date of publication could influence on the quality of observational studies.