Abstract
BACKGROUND: Osteoarthritis (OA) is a leading cause of pain, disability, and reduced quality of life among middle-aged and older adults. Understanding its global epidemiological patterns and attributable risk factors is essential for public health planning. This study quantified the burden of OA among adults aged 55 years and older, evaluated temporal trends from 1990 to 2021, and projected future trends through 2050. METHODS: Data on OA incidence, prevalence, and disability-adjusted life years (DALYs) were obtained from the Global Burden of Disease Study 2021 (GBD 2021). OA cases were defined by symptomatic and radiographically confirmed criteria. Age-standardized rates (ASRs) per 100,000 population were calculated, and temporal trends were analyzed using estimated annual percentage change (EAPC). High body mass index (BMI ≥25 kg/m(2)) was assessed as an attributable risk factor. Age-period-cohort (APC) models were applied to assess independent effects of age, calendar period, and birth cohort. Bayesian APC (BAPC) models projected OA burden through 2050. Analyses were stratified by sex, age group, region, and Sociodemographic Index (SDI) quintile. RESULTS: In 2021, 23.86 million older adults were newly diagnosed with OA globally (ASIR 1,610.95 per 100,000), with 453.56 million living with OA (ASPR 30,395.11 per 100,000) and 16.05 million DALYs (ASDR 1,075.70 per 100,000) among adults aged 55 years and older. All metrics showed significant upward trends since 1990. High-SDI regions exhibited the highest burden. Age, period, and cohort analyses revealed rising incidence peaked at 55-59 years, simultaneously, OA risks in more recent birth cohorts and persistent increases with advancing age. Females consistently experienced higher rates than males. Globally, 35.8% of OA-related DALYs were attributable to high BMI, with the greatest burden in High-income North America. Projections indicate further increases by 2050 (ASIR 9%, ASPR 14%, ASDR 12%). CONCLUSION: OA imposes a substantial and increasing health burden on middle-aged and older adults globally, with notable variations across regions, sex, age, and SDI levels. High BMI contributes significantly to this burden. Our projections indicate continued growth in OA incidence and disability, emphasizing the need for targeted prevention and intervention strategies to reduce risk factors and improve population health outcomes.