Disparities in incident osteoarthritis between sexual minority and heterosexual adults: Findings from a large cohort study

Sexual minorities, including lesbian, gay, and bisexual individuals, experience persistent health disparities due to chronic exposure to minority stressors; however, its relation to osteoarthritis (OA) risk remains unexplored. This study aims to investigate the association between sexual orientation and OA risk and evaluate the mediating effect of health behaviors and psychosocial factors in related disparities.

We conducted a prospective cohort study of 346,320 UK Biobank participants without OA at baseline (2006-2010), followed through December 2021. Coarsened exact matching was applied to balance age, birth cohort, and ethnicity. Sex-stratified Cox models (using age as the time scale) were used to estimate hazard ratios (HRs) for OA risk. Mediation analyses examined the roles of modifiable factors, including body mass index (BMI), socioeconomic status, lifestyle behaviors, and mental health.

Over a median follow-up of 11.3 years, 40,728 participants developed OA. Both bisexual and lesbian women had a higher OA risk than heterosexual women (adjusted HR: 1.17, 95%CI [confidence interval]: 1.07-1.28 and HR: 1.36, 95%CI: 1.10-1.68, respectively). Mediation analysis identified BMI, Townsend index, smoking, and depression as potential mediators, with mediation proportions ranging from 12.1% to 34.2%. In men, gay individuals had lower OA risk (HR: 0.72, 95%CI: 0.60-0.85), with BMI and education explaining 17.5-18.4% of the reduction; no significant difference was observed for bisexual men.

Sexual orientation is associated with OA risk, with bisexual and lesbian women showing higher risk and gay men lower risk than heterosexuals. These disparities are partially explained by BMI, smoking, depression, and socioeconomic status.