Global and regional temporal changes in cross-country inequalities of site-specific osteoarthritis burden, 1990 to 2021

Objective: This study examined the global and regional temporal changes in cross-country inequalities of site-specific osteoarthritis (OA) burden from 1990 to 2021. Methods: Age-standardized years lived with disability rates (ASYRs) for site-specific OA across 204 countries and territories were obtained from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021. The slope index of inequality (SII) and the concentration index (CCI) were calculated to quantify the absolute and relative cross-country inequalities. Average annual percent change (AAPC) was used to assess the temporal changes. Results: From 1990 to 2021, the ASYR of OA increased regardless of the joint affected globally. The SII of total OA exhibited an improving cross-country inequality among higher sociodemographic index (SDI) countries and territories, decreasing from 77.26 (95% confidence interval [CI] 69.32–85.20) to 69.85 (95% CI 60.67–79.02). Similarly, the CCI of total OA decreased from 0.0815 (95% CI 0.0732–0.0897) to 0.0622 (95% CI 0.0551–0.0693). However, most regions exhibited worsening cross-country inequalities among higher SDI countries and territories. Central sub-Saharan Africa showed the largest worsening inequality in SII (AAPC 4.55, 95% CI 2.83–6.29), whereas east Asia showed the largest worsening inequality in CCI (AAPC 1.96, 95% CI 1.48–2.43). Hand OA showed consistently improving absolute and relative cross-country inequalities among higher SDI countries and territories, whereas other OA showed consistently worsening inequalities. Conclusion: The cross-country inequalities of OA burden have persisted and even worsened in some regions over the past decades. Targeted prevention and management strategies according to geographic location and affected joint are pivotal to reduce the growing OA burden and achieve equity in health outcomes.