Non-linear relationship between platelet count and 30-day in-hospital mortality in ICU patients with acute myocardial infarction: a multicenter retrospective cohort study.

Acute myocardial infarction (AMI) remains a major global health challenge with high mortality rates. This study investigated the association between platelet count and 30-day in-hospital mortality in critically ill AMI patients. This multicenter retrospective cohort study analyzed 6,850 critically ill AMI patients from 208 U.S. hospitals (2014-2015) using the eICU Collaborative Research Database v2.0. The primary exposure was baseline platelet count within 24 h of ICU admission. The primary outcome was 30-day in-hospital mortality. Analyses were adjusted for demographics, laboratory parameters, disease severity, comorbidities, and treatments. A U-shaped relationship was identified between platelet count and mortality, with an inflection point at 147 × 10⁹/L. Below this threshold, each 10 × 10⁹/L increase in platelet count was associated with decreased mortality (OR = 0.931, 95% CI: 0.892-0.973, P = 0.001). Above the threshold, each 10 × 10⁹/L increase was associated with increased mortality (OR = 1.023, 95% CI: 1.010-1.036, P < 0.001). A U-shaped relationship was observed between platelet count and 30-day in-hospital mortality in critically ill AMI patients, with optimal outcomes observed at approximately 147 × 10⁹/L, suggesting that platelet count may serve as a potential risk stratification marker.