Biological Sex Is Under-Reported in Cartilage-Related Preclinical Research: A Cross-Sectional Analysis.

Background: Intervertebral disc degeneration (IDD) and osteoarthritis (OA) share many similarities in the molecular processes involved in the onset and progression of these musculoskeletal pathologies. Biological sex is a risk factor for both conditions. Sex bias in orthopedic preclinical research affects knowledge, reproducibility, and translational aspects of basic research. This article aims to provide a comprehensive overview of how donor sex is reported in IDD and OA preclinical research using human or animal samples and in vivo models. Methods: We performed a cross-sectional study, searching original articles from journals with the highest impact factor in the field, to determine: (i) whether they report donor sex, and if so, whether they include this data in the analysis; and (ii) whether journals have requirements for sex reporting. Results: Our research has four main outcomes. First, donor sex was reported in only 61.9% of the 284 cases examined. Second, among the studies where sex was reported (176), samples were predominantly from only male donors or animals (56%). Moreover, sex was rarely incorporated as a variable in outcome analysis (3.4% of cases). Finally, although 14 out of 23 journals stipulated sex reporting requirements, 37.7% of papers published in these journals failed to report donor sex. Conclusions: Our results provide evidence for the under-reporting of sample donor sex in OA and IDD research, which may contribute to the poor translation to clinical efficacy and the replication crisis. Our findings could guide journal policies, institutional guidelines for preclinical research, and funder requirements.