Sex bias exists in basic science and translational surgical research

Background. Although the Revitalization Act was passed in 1993 to increase enrollment of women in clinical trials, there has been little focus on sex disparity in basic and translational research. We hypothesize that sex bias exists in surgical biomedical research. Methods. Manuscripts from Annals of Surgery, American Journal of Surgery, JAMA Surgery, Journal of Surgical Research, and Surgery from 2011 to 2012 were reviewed. Data abstracted included study type, sex of the animal or cell studied, location, and presence of sex-based reporting of data. Results. Of 2,347 articles reviewed, 618 included animals and/or cells. For animal research, 22% of the publications did not specify the sex of the animals. Of the reports that did specify the sex, 80% of publications included only males, 17% only females, and 3% both sexes. A greater disparity existed in the number of animals studied: 16,152 (84%) male and 3,173 (16%) female (P < .0001). For cell research, 76% of the publications did not specify the sex. Of the papers that did specify the sex, 71% of publications included only males, 21% only females, and 7% both sexes. Only 7 (1 %) studies reported sex-based results. For publications on female-prevalent diseases, 44% did not report the sex studied. Of those reports that specified the sex, only 12% studied female animals. More international than national (ie, United States) publications studied only males (85% vs 71%, P = .004), whereas more national publications did not specify the sex (47% vs 20%, P < .0001). A subanalysis of a single journal showed that across three decades, the number of male-only studies and usage of male animals has become more disparate over time. Conclusion. Sex bias, be it overt, inadvertent, situational, financial, or ignorant, exists in surgical biomedical research. Because biomedical research serves as the foundation for subsequent clinical research and medical decision-making, it is imperative that this disparity be addressed because conclusions derived from such studies may be specific to only one sex.