Beta-blocker use and all-cause mortality in myocardial infarction survivors: A retrospective cohort study using propensity score methods in NHANES 1999 to 2018

Beta-blockers are recommended for post-myocardial infarction (MI) care, but their long-term impact on all-cause mortality in real-world settings remains unclear. This study investigates the association using propensity score methods in a nationally representative cohort, with sensitivity analyses across age subgroups. This retrospective cohort study analyzed data from the National Health and Nutrition Examination Survey, restricted to 2308 MI survivors. Beta-blocker use was the exposure (0: nonuse, 1: use). All-cause mortality, assessed via mortality status (MORTSTAT), was the outcome, with follow-up time measured in person-months from interview (PERMTH_INT). Covariates included age, sex, ethnicity, marital status, poverty-income ratio, education, smoking, alcohol use, and body mass index. Cox proportional hazards regression, propensity score adjustment, matching, and inverse probability of treatment weighting were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). Age-stratified sensitivity analyses were conducted for subgroups ≥30, ≥55, ≥60, ≥70, ≥75, and 30-80 years to assess the average treatment effect (ATE). Of 2308 participants (mean age 68.7 years, 65% male), 15% used β-blockers. The crude HR was 0.81 (95% CI: 0.68-0.96, P = .0178). After multivariable adjustment, the HR was 1.03 (95% CI: 0.86-1.24, P = .7296). Propensity score-matched ATE HR was 0.93 (95% CI: 0.70-1.23, P = .6029); inverse probability of treatment weighting ATE HR was 1.02 (95% CI: 0.83-1.24, P = .8786). Weighted Kaplan-Meier estimates showed modest but nonsignificant absolute risk reductions of 1.17% (95% CI: 0.2-2.1) at 5 years and 0.81% (95% CI: 0.1-1.5) at 10 years, as confidence intervals overlapped substantially with no statistical significance in the differences. Age-stratified analyses showed consistent null effects post-adjustment (e.g., ≥70 years adjusted HR 0.98, P = .8992). Subgroup analyses suggested potential benefits in females (HR 0.70, P = .0290), low-education, and low-income groups, though interactions were nonsignificant. Beta-blocker use was not associated with reduced all-cause mortality in MI survivors after confounder adjustment, with robust findings across age subgroups. These results support personalized therapy approaches rather than routine use. Limitations include potential residual confounding due to the absence of key clinical variables (e.g., left ventricular ejection fraction, revascularization status).