Obstetrics & Gynecology in 1996: marking the progress toward evidence-based medicine by classifying studies based on methodology.

OBJECTIVE

To test the hypothesis that researchers in obstetrics and gynecology favor an observational type of study design.

DATA SOURCES

The 12 regular issues of Obstetrics & Gynecology published during 1996 were analyzed.

METHOD OF STUDY SELECTION

All articles in the journal Obstetrics & Gynecology were reviewed for the year 1996, except that separate issues covering case reports, case condensations, and reviews were excluded.

TABULATION, INTEGRATION, AND RESULTS: Studies were classified as observational or experimental. Observational studies were subclassified as either descriptive, case-control, or cohort. Experimental studies were subclassified as either randomized controlled trial (RCT) or uncontrolled trial. Other study designs were noted. Of the 316 studies published during 1996, 241 (76%) were observational, 43 (14%) experimental, and 32 (10%) other. There were 162 (51%) descriptive studies, 44 (14%) case-control studies, 35 (11%) cohort studies, 35 (11%) RCTs, and eight (3%) uncontrolled trials.

CONCLUSION

Researchers who publish in Obstetrics & Gynecology favor an observational study design. With evidence-based medicine growing in popularity as a new standard or paradigm, the reliance on observational studies may have implications.