To describe the trends of research design in publications from high-impact medical journals. Methods: A cross-sectional, descriptive study was conducted by searching the 2011 electronic publications of the journals: New England Journal of Medicine, Journal of the American Medical Association, The Lancet, British Medical Journal, and Annals of Internal Medicine. Studies were classified as primary and secondary. The journal impact factor was taken from the Journal Citation Report website. Descriptive statistics were used to analyze and interpret the data. Results: We analyzed 1130 publications: 804 primary and 326 secondary studies, which represented
71.2% and 28.8% of the total publications, respectively. Among the primary studies, randomized clinical trials (30.4%) were the most prevalent, followed by cohort studies (21.9%) and case reports (9.0%). Conclusions: These findings can have implications in Evidence-Based Medicine programs. Literature review should focus on reviewing secondary articles first, then experimental studies and finally, observational studie
