Admission platelet-to-hemoglobin ratio and 1-year outcomes after percutaneous coronary intervention: a multicenter registry cohort study.

Background: The platelet-to-hemoglobin ratio (PHR) is a proposed prognostic marker in cardiovascular disease, but it has not been evaluated against a broad major adverse cardiovascular events (MACE) endpoint in a dedicated percutaneous coronary intervention (PCI) cohort, and whether it adequately summarizes its two components remains untested. Methods: We analyzed 1,551 patients pooled from two prospective Korean drug-eluting stent registries (2016-2022). The PHR was calculated as platelet count (×10⁹/L) divided by hemoglobin (g/L). The primary endpoint was 1-year MACE, with follow-up censored at 365 days, a composite of all-cause death, myocardial infarction, stroke, repeat revascularization, or heart failure hospitalization. Multivariable Cox models included eight prespecified clinical covariates; the functional form was examined with restricted cubic splines, and the PHR was decomposed using nested models and a log-scale ratio-constraint test. Results: MACE occurred in 107 patients (6.9%) within 1 year. A higher PHR was independently associated with MACE (adjusted hazard ratio [HR] per 1-standard deviation, 1.21; 95% confidence interval [CI], 1.05-1.40; Conclusions: The admission PHR was independently associated with 1-year MACE after PCI, with no evidence of nonlinearity, and its log-scale component effects were compatible with the ratio constraint in this cohort. Given the negligible gain in discrimination and net benefit, the PHR is an independent prognostic marker rather than a tool for risk reclassification.