Associations between total and regional fat-to-muscle mass ratio and osteoarthritis incidence: A prospective cohort study.

OBJECTIVE

To investigate the associations between total and regional fat-to-muscle mass ratio (FMR) and incident osteoarthritis among adults.

DESIGN

This prospective cohort study included 328,549 participants from the UK Biobank. FMR was calculated as the ratio of fat mass to muscle mass for the whole body, trunk, arms, and legs using a body composition analyzer. Incident osteoarthritis was identified via ICD-10 codes. Cox proportional-hazard regression models were used to identify the association between each type of FMR separately and incident osteoarthritis. Subgroup analyses by age, sex and specific joint sites were conducted.

RESULTS

During a median follow-up of 14.4 years, 48,997 incident osteoarthritis cases were identified. We found an increasing trend in incident osteoarthritis with higher FMRs, particularly among females. In the fully adjusted models, each one standard deviation increase in arm FMR was associated with a 6% higher hazard in males and 11% in females. For leg FMR, the corresponding increases were 5% in males and 14% in females, respectively. Whole-body and trunk FMR were significantly associated with osteoarthritis risk only in women.

CONCLUSIONS

FMR was generally positively associated with osteoarthritis risk, with significant associations for arm and leg FMR remaining independent of body mass index across sex and age subgroups. These findings highlight FMR as a valuable marker for identifying those at risk of incident osteoarthritis.