Impact of health insurance on long-term mortality after percutaneous coronary intervention in acute coronary syndrome patients: a nationwide propensity-weighted analysis

Background/Introduction Acute Coronary Syndrome (ACS) remains a leading cause of mortality worldwide. In Thailand, healthcare access is provided by three main public insurance schemes: the Universal Coverage Scheme (UCS), the Social Security Scheme (SSS), and the Civil Servant Medical Benefit Scheme (CSMBS). Although UCS has improved access to essential care, it remains to be determined whether insurance scheme is associated with long-term survival after percutaneous coronary intervention (PCI). Purpose To assess the impact of a patient's health insurance scheme on their long-term mortality risk for patients undergoing PCI for ACS. Using a nationwide registry, we hope these real-world findings can guide policies to improve healthcare equity. Methods We performed a retrospective cohort study of patients treated for ACS between May 2018 and August 2020. To evaluate long-term survival, we connected clinical data to the Department of Provincial Administration, which enabled us to monitor all-cause mortality through 2026. Since baseline health is significantly dependent on insurance type, we used inverse probability weighting (IPW) to balance the groups (keeping standardised mean differences under 0.2 and aligning variance ratios close to 1). Subsequently, we estimated adjusted hazard ratios (HR) for all-cause mortality using a multivariable Cox proportional hazards model to control for clinical and procedural risk factors. Results The study included 12,280 patients (8,612 UCS; 2,820 CSMBS; 848 SSS). Baseline disease severity varied significantly; with UCS (50.66%) presenting with a higher ST-elevation myocardial infarction (STEMI) rate than CSMBS (37.41%). After balancing the groups using propensity score weighting, the survival curves show a clear difference. Compared with CSMBS, UCS was associated with higher long-term mortality (HR 1.32; 95% CI 1.18–1.46; p<0.001). Mortality risk was similar between SSS and CSMBS (HR 0.81; 95% CI 0.55–1.20; p=0.296). New requirement for dialysis was the strongest predictor of death (HR 2.83; 95% CI 1.66–4.80; p<0.001), followed by heart failure (HR 2.31; 95% CI 1.57–3.40; p<0.001). We also observed an obesity paradox: underweight status increased mortality risk (HR 1.44; 95% CI 1.01, 2.06; p=0.042), while obesity (Body mass index ≥ 25.0 kg/m2) appeared protective (HR 0.62; 95% CI 0.50, 0.77; p<0.001). Finally, the use of statins (HR 0.57; 95% CI 0.40, 0.80; p=0.001) or beta-blockers (HR 0.60; 95% CI 0.46, 0.77; p<0.001) was strongly associated with improved long-term survival. Conclusion(s) UCS patients had significantly higher long-term mortality after PCI for ACS after adjusting for baseline clinical and procedural differences relative to patients with CSMBS. This disparity highlights a need for targeted health policies to ensure equitable chances of survival for all patients, regardless of their insurance coverage.