Association between central obesity and the risk of glenohumeral joint osteoarthritis: a prospective study.

BACKGROUND: The relationship between obesity and glenohumeral joint osteoarthritis (GJO) has long been a subject of doubt. Although body mass index (BMI) has been recognized as a risk factor by guidelines, it fails to reflect fat distribution, which may limit its clinical application value. Waist-to-height ratio (WHtR), as an indicator of central obesity, has shown good predictive performance in metabolic-related diseases. However, its role in GJO remains unclear. This study aimed to investigate the relationship between central obesity and GJO through a prospective cohort study in the UK Biobank (UKB). METHODS: We conducted a prospective cohort study based on the UK Biobank, including 32,900 adults who participated in the baseline survey between 2006 and 2014 and had no history of GJO. The median follow-up time was 8.85 years (IQR: 7.15 - 10.75). Cox proportional hazards models were used to assess the association between WHtR levels at baseline and the incidence of new GJO at the end of follow-up. Interaction and sensitivity analyses were conducted in different BMI strata. RESULTS: A significant linear correlation was observed between WHtR levels at baseline and the incidence risk of GJO at the end of follow-up (P < 0.001). Compared with individuals with normal WHtR at baseline, those with central obesity had a 1.52-fold increased risk of GJO (AHRs = 1.52, 95% CI: 1.02-2.26, P = 0.039), independent of BMI. Further analysis revealed that this association was more significant in the secondary GJO population (AHR = 1.74, 95% CI: 1.10-2.76, P = 0.019). Additionally, in the population with normal BMI at baseline, individuals with WHtR ≥ 0.5 had a 1.94-fold increased risk of GJO (AHRs = 1.94, 95% CI: 1.01-3.72, P = 0.046), but no significant association was observed in the population with overweight or obese BMI at baseline (P = 0.492;0.998). Subgroup analysis showed that individuals under 65 years old, females, those with insufficient physical activity, and those with lower occupational physical activity had a higher risk (P = 0.014; 0.046; 0.005; 0.007). CONCLUSIONS: Central obesity is significantly associated with the risk of GJO, especially in the secondary GJO and normal BMI populations, suggesting that fat distribution should be included in the early screening and risk assessment system for GJO.