Physical Inactivity and Non-communicable Disease Burden in Five ASEAN Countries: A 12-Year Panel Analysis Using Structural Equation Modeling and Machine Learning Projections.

Objectives: Non-communicable diseases (NCDs) are a leading cause of preventable mortality in Southeast Asia, but population-level evidence linking physical inactivity to NCD burden across the Association of Southeast Asian Nations (ASEAN) remains limited. This study quantified associations between physical inactivity prevalence and NCD-related disability-adjusted life years (DALYs), cardiovascular mortality, and diabetes prevalence across five ASEAN countries from 2010 to 2021 and projected 2025 NCD burden trajectories under an exploratory business-as-usual scenario. Methods: A longitudinal panel dataset of 60 country-year observations was analyzed using fixed-effects regression with Driscoll-Kraay standard errors, partial least squares structural equation modeling, and XGBoost machine learning with Shapley additive explanations. Missing data (2.1-6.4%) were handled using multiple imputation by chained equations. Results: Physical inactivity was independently associated with NCD DALYs (β=0.421; 95% confidence interval, 0.251 to 0.591; p<0.001). A significant attenuating interaction with the universal health coverage (UHC) index was observed (β=-0.183; 95% CI, -0.358 to -0.008; p=0.041). Because the UHC index was rescaled to 10-point units, this indicates that for every 10-point increase in the UHC index, the regression coefficient for physical inactivity decreased by 0.183 units (DALYs per 100 000 population), demonstrating a significant buffering effect of health system coverage on the inactivity-NCD association. The structural equation model explained 78.2% of the variance in NCD burden and identified a significant exploratory longitudinal indirect association through health system resilience, with 19.8% of the total association mediated through this pathway. Under the exploratory business-as-usual scenario, NCD DALYs were projected to increase by 7.8-20.9% by 2025, with Indonesia and the Philippines showing the highest projected increases. Conclusions: UHC expansion may attenuate inactivity-related NCD burden. For ASEAN countries undergoing rapid epidemiological transition, coordinated investment in health system capacity and multisectoral physical activity promotion may help limit projected DALY increases and support progress toward Sustainable Development Goal 3.