Background and Aim: Although the prevalence of knee osteoarthritis (OA) in Asian populations has been explored, there is limited documentation on the incidence of knee OA. This study sought to determine the incidence and progression of radiographic knee OA, as well as identify its risk factors, within the Vietnam Osteoporosis Study (VOS).
Methods: This population-based longitudinal study included 2,284 participants aged 40 years and older, who were randomly recruited from Ho Chi Minh City, Vietnam. Knee radiographs were classified from grades 0 to 4 using the Kellgren and Lawrence scale, with grades 2 or higher indicating knee OA. Whole body fat mass and lean mass was measured using DXA (Hologic Corp, USA). Incidence and progression rates were calculated, and multiple logistic regression models were employed to identify risk factors, including age, sex, body mass index (BMI), fat mass, and lean mass.
Results: During a two-year follow-up period, the incidence of radiographic knee OA was 8.9% (95% confidence interval [CI]: 7.4-10.5). Women had a higher incidence rate (10.0%) compared to men (6.6%). Progression of knee OA was observed in 11.1% (95% CI: 8.3-14.5) of participants who had OA at baseline. Significant risk factors for the incidence of knee OA included advancing age (odds ratio [OR]: 1.3 per 5 years, 95% CI: 1.2-1.4), female sex (OR: 1.6, 95% CI: 1.0-2.5), and higher fat mass (OR: 1.27 per 5 kg, 95% CI: 1.0-1.5). For the progression of knee OA, higher fat mass (OR: 1.34 per 5 kg, 95% CI: 1.0-1.8) was the only significant risk factor.
Conclusion: These findings suggest a substantial incidence of knee OA, with high fat mass being a key risk factor. The finding underscores the importance of addressing modifiable risk factors such as body fat to potentially reduce the burden of knee OA in this population.