23 years of public policy towards universal health coverage in Mexico. A cross-sectional time-series analysis using routinely collected health data, 2000-2022.

Background: Mexico's health system has undergone multiple reforms over the past two decades to expand coverage. This study examines their association with public health expenditure, infrastructure, human resources, hospital admissions and premature mortality, providing evidence to guide investment strategies and health policy. Methods: We conducted a cross-sectional time-series analysis using routinely collected data (2000-2022). The primary outcome was premature mortality; secondary outcomes included public health expenditure, number of hospital beds, consulting rooms, physicians, nurses, and hospital admissions. Trends were assessed with marginal models using linear splines aligned with governmental transitions, comparing populations with (PWSS) and without (PLSS) social security coverage. Findings: Public health expenditure increased from 2000 to 2012, with steeper growth for PLSS, but plateaued for both groups during 2012-2018. Hospital bed gap narrowed between 2003 and 2006; however, the ratio in Ministry of Health hospitals serving PLSS (5.84 per 10,000) remained 20.1% lower than in social security institutions serving PWSS (7.31). Physician availability improved for PLSS, yet disparities persisted. Hospital admissions in Ministry of Health hospitals increased from 2004 to 2012, then declined by -5.73% annually after 2018; admissions in social security institutions decreased by -2.4% annually during 2012-2018. Among PLSS, preventable and treatable mortality rose after 2012 (+3.26% and +5.54% annually, after 2018), while both indicators declined steadily among PWSS. Interpretation: Despite major reforms with significant public expenditure increase, inequities between PLSS and PWSS, fragmentation, accessibility and quality challenges persist. Addressing the root causes of health inequities in Mexico will require not only health system reforms but also tackling structural vulnerabilities linked to widespread informal employment, which limits access to health and social protection. Funding: National Institute of Public Health, Ministry of Science, Humanities, Technology and Innovation of Mexico.