Global Co-Burden and Risk Factors of Low Back Pain and Osteoarthritis: Analysis of Global Burden of Disease 2021 Data Based on Machine Learning and SHAP.

Background: Low back pain (LBP) and osteoarthritis (OA) are leading causes of disability in the elderly, but a global analysis of their comorbidity patterns and risk factors is lacking. The goal of this study was to examine the global epidemiology and risk factors of their comorbidity. Methods: We analyzed the incidence, prevalence, and Years Lived with Disability (YLDs) for people aged 50 years and older for 204 countries and territories from the Global Burden of Disease 2021 study. Random Forest models with SHAP (Shapley Additive exPlanations) values were applied, and important risk factors were identified. Thereafter, multiple linear regression models with backward stepwise selection were applied to categorize the risk factors into the shared risk factors, OA-specific factors, and LBP-specific factors. Finally, we simulated the potential effect of risk factor interventions on disease burden. Results: The global burden of OA was greatest in high-income countries, whereas the LBP burden was greatest in Europe and Central Asia. A Random Forest analysis revealed primary risk factors, including environmental and occupational exposures for OA, and metabolic and ergonomic factors for LBP. Five shared risk factors were found in both sexes combined, primarily dietary factors and low bone mineral density. Notably, high body mass index was identified as an OA-specific risk factor, while smoking and occupational ergonomic factors were distinctly LBP-specific. The interventions that had the largest burden reduction were those that targeted the shared risk factors, including indirect cascade effects. Conclusion: The co-burden of LBP and OA is a complex phenomenon attributed to shared and disease-specific risk factors, highlighting the need for prevention strategies that are tailored by sex and geographic region.