Distribution of study designs in four major US journals of obstetrics and gynecology

To classify and compare articles, based on the study design, in four leading US obstetrics and gynecology journals.

One year of each journal, American Journal of Obstetrics and Gynecology (AJOG), Obstetrics and Gynecology (O&G), Gynecologic Oncology (GO), and Fertility and Sterility (F&S), beginning May 1997, was reviewed. Supplementary issues were excluded from review. The percentage of articles devoted to observational versus experimental study design was determined, and the quality of evidence was assessed including how heavily randomized controlled trials were represented versus other study designs.

1,517 articles were reviewed. The average percentage of clinical research articles was 90.4. The percentage of animal studies were 10.7 (AJOG), 1.1 (O&G), 1.1 (GO) and 4.2 (F&S) (chi(2) p < 0.001). There were 5.3, 1.9, 6.5, and 7.5% basic science articles, respectively (chi(2) p = 0.007). The average percentage of observational articles was 68.2 and that of experimental articles was 14.1. The percentages of total articles classified as controlled experimental were 10.9 (AJOG), 14.6 (O&G), 5.1 (GO), and 15.2 (F&S) (chi(2) p = 0.01). There were 8.7, 11.1, 3.3 and 9.5% randomized controlled trials, respectively (chi(2) p = 0.008).

The majority of research reviewed was clinical, and more than half of the articles were observational. Under the US Preventative Services Task Force rating system, the randomized control trial is given the highest rating - class I evidence. The drive toward evidence-based clinical practice may not be fully supported by researchers in obstetrics and gynecology, as reflected by submissions to and publications in the major obstetrics and gynecology journals.