Long-term trends and the role of health resources in under-5 mortality rates: a 2000-2021 longitudinal analysis at the global level.

OBJECTIVE: The under-5 mortality rate (U5MR) is a crucial global health metric for evaluating public health interventions, and further reductions in U5MR are essential for achieving the Sustainable Development Goals (SDGs). This study analyses the trends of U5MR globally from 2000 to 2021 and explores the quantitative impact of health resources on U5MR reduction. DESIGN AND PARTICIPANTS: This study used WHO public data from 2000 to 2021 to investigate the temporal trend of U5MR through Joinpoint regression analysis. A two-way fixed-effect model was used to investigate the relationship between U5MR and health resources. PRIMARY OUTCOME MEASURES: Data on U5MR and health resources (including six vaccine-related indicators and eight health expenditure-related indicators) were obtained from the WHO Global Health Observatory, encompassing 200 countries and regions from 2000 to 2021. RESULTS: Globally, U5MR declined, though at a slower pace (annual average percentage change: -3.259, p<0.001), while vaccination coverage and health expenditures increased (p<0.05). We found a significant negative correlation of global polio vaccination coverage (β=-0.489, p<0.05) and current health expenditure (CHE) as percentage of gross domestic product and U5MR (β=-0.762, p<0.05) with U5MR. In G20 countries, domestic general government health expenditure as percentage of CHE was negatively correlated with U5MR (β=-0.553, p<0.05). Health resources contributed to 65.01% of U5MR reduction in G20 countries, with vaccines accounting for 23.86%. Globally, health resources contributed 37.26% to U5MR reduction, with vaccines accounting for 72.69%. CONCLUSION: Global U5MR has declined from 2000 to 2021, but progress remains insufficient to fully achieve the SDGs. Immunisation played a dominant role in the global reduction of U5MR, underscoring the critical need to prioritise vaccination in health resource allocation strategies.