Strengthening health systems in low and middle-income countries: performance determinants and pathways to universal health coverage

Background: Health systems in low- and middle-income countries (LMICs) face persistent challenges in achieving universal health coverage (UHC). The COVID-19 pandemic exposed critical weaknesses in governance, financing, and infrastructure, while recent global reports indicate stalled progress toward health-related Sustainable Development Goals. This study addresses the need for evidence-based strategies to strengthen health systems by identifying key performance determinants and efficient resource allocation pathways. Methods: We constructed a longitudinal dataset for 135 LMICs (2000-2023) from WHO, World Bank, IHME, DHS/MICS, and ITU, using explicit imputation procedures to address irregular survey intervals. We employed fixed effects, system GMM, and structural equation modeling to analyze determinants of health system performance. Based on these econometric estimates, we developed mathematical optimization models (linear, multi-objective, and stochastic programming) to identify efficient resource allocation strategies under budget constraints. Inequality was analyzed using concentration indices and decomposition. Findings: < 0.05) show significant positive associations with UHC service coverage. Governance quality mediates multiple pathways, with corruption linked to an estimated 22% efficiency loss in sensitivity analyses. Model-based scenarios suggest that reallocating 15% of current health budgets toward primary care and digital infrastructure could potentially avert approximately 1.2 million annual deaths (uncertainty range: 0.9-1.6 million) and reduce catastrophic health expenditures by an estimated 18% (range: 14%-23%). Pro-rich inequalities persist, particularly for non-communicable disease services and maternal health. Interpretation: Strengthening health systems requires coordinated investments in governance, primary care, digital health, and financial protection. Our econometric and model-based analyses provide illustrative policy pathways. Reallocating existing resources and prioritizing primary care and pro-poor targeting could accelerate UHC progress. Policymakers should adopt integrated, context-specific strategies that balance efficiency, equity, and resilience.