Gender bias in clinical case reports: A cross-sectional study of the "big five" medical journals

Background Gender bias in medical journals can affect the science and the benefit to patients. It has never been investigated in clinical case reports. The oversight is important because of the role clinical case reports play in hypothesis generation and medical education. We investigated contemporary gender bias in case reports for the highest ranked journals in general and internal medicine. Methods PubMed case reports data from 2011 to 2016 were extracted for the Annals of Internal Medicine, British Medical Journal, the Journal of the American Medical Association, The Lancet, and New England Journal of Medicine. The gender of the patients were identified and a text analysis of the Medical Subject Headings conducted. Results A total of 2,742 case reports were downloaded and 2,582 (95.6%) reports contributed to the final analysis. A pooled analysis showed a statistically significant gender bias against female case reports (0.45; 95% CI: 0.43 - 0.47). The Annals of Internal Medicine was the only journal with a point estimate (non significant) in the direction of a bias against male patients. The text analysis identified no substantive difference in the focus of the case reports and no obvious explanation for the bias. Conclusion Gender bias, previously identified in clinical research and in clinical authorship, extends into the patients presented in clinical case reports. Whether it is driven by authors or editors is not clear, but it likely contributes to and supports an overall male bias of clinical medicine.