The impact of high BMI on the global burden of osteoarthritis from 1990 to 2021 and future projections.

Introduction: Osteoarthritis (OA) is a major global cause of disability, predominantly affecting weight-bearing joints such as the knee and hip. High body mass index (BMI) is a well-established modifiable risk factor for OA. This study aimed to estimate the global burden of OA attributable to high BMI from 1990 to 2021 and to project its trends through 2036 using the Global Burden of Disease (GBD) 2021 database. Methods: We analyzed OA-related years lived with disability (YLDs) attributable to high BMI, focusing on knee and hip OA. Regional and sociodemographic disparities were evaluated using the Socio-demographic Index (SDI). Future burden trends were projected using a Bayesian Age-Period-Cohort (BAPC) model. Frontier analysis was employed to assess potential gains in health system performance. Results: From 1990 to 2021, global OA YLDs attributable to high BMI increased substantially, driven by rising obesity rates, population aging, and demographic changes. Knee OA showed the greatest increase, especially in low- and middle-SDI regions, whereas hip OA burdens were more concentrated in high-SDI regions. The BAPC model projected continued increases in YLDs through 2036. Frontier analysis revealed substantial gaps between actual and optimal OA burdens, particularly in developing regions. Discussion: Our findings highlight the growing impact of high BMI on OA burden, with pronounced regional inequalities. There is an urgent need for targeted prevention strategies, improved OA management, and optimized resource allocation, especially in low-SDI and rapidly developing areas. These results support the development of precision public health strategies to mitigate the rising burden of BMI-related OA worldwide.