Sex bias persists in surgical research: A 5-year follow-up study

Background: Federal initiatives have recently addressed the sex bias that exists in biomedical and clinical research. However, improvement to the inclusion of sex as a biological variable remains unknown. Methods: We performed a 5-year follow-up study of all clinical and biomedical research articles published in 5 surgical journals from January 1, 2017, through December 31, 2018. Human, animal, and cell subjects were analyzed for study/subject type, sex of participants, sex matching, and sex-based data reporting, analysis, and discussion. Results: Comparing 2017 to 2018 with 2011 to 2012, slightly more articles reported the sex of the human studied (87% vs 83%; P = .001). Inclusion of both sexes remained high (94% vs 95%; P = .22), but sex-based data reporting (36% vs 38%; P = .17), analysis (35% vs 33%; P = .39), and discussion of results (10% vs 23%; P < .0001) remained unchanged or worsened. Regarding animal research, the number of articles that stated the sex studied remained unchanged (79% vs 78%; P = .67); if stated, slightly more included both sexes (7% vs 3%; P = .002). Regarding cell research, fewer articles reported the sex of the cells studied (5% vs 24%; P = .0001); if stated, more articles included both sexes, but the difference did not reach statistical significance (25% vs 7%; P = .34). Sex matching remained poor with only 50% of human, 4% of animal, and 9% of cell studies matching the inclusion of both sexes by at least 50%. Conclusion: Sex bias persists in surgical research. The majority of articles failed to report, analyze, or discuss results based on sex, which will negatively affect clinical translatability and outcomes of evidence-based medicine.