Coefficient of variation of platelet count as a prognostic Indicator for intracerebral hemorrhage: findings from a multicenter cohort.

Background: Platelet count fluctuations are common in patients with intracerebral hemorrhage (ICH), but the prognostic relevance of these fluctuations remains uncertain. Methods: We conducted a retrospective multicenter cohort study using MIMIC-IV as the primary cohort and an independent Chinese cohort for external validation. Platelet count CV was calculated as the sample standard deviation divided by the mean of at least three observed, nonmissing platelet measurements obtained during the index hospitalization within 15 days before ICU admission. Missing measurement fields were excluded and were not treated as zero. Logistic regression, Cox models, restricted cubic splines, Kaplan-Meier analyses, subgroup analyses, reclassification metrics, and sensitivity analyses were performed. Primary multivariable models additionally adjusted for platelet measurement count, and effect estimates were reported per 0.1-unit increase in CV. Results: The primary cohort included 2,202 patients, of whom 294 died during the index hospitalization. After adjustment for clinical covariates and platelet measurement count, each 0.1-unit increase in platelet count CV was associated with in-hospital mortality (OR, 1.21; 95% CI, 1.07-1.38; Conclusion: Higher pre-ICU platelet count CV was associated with mortality after adjustment for clinical covariates and platelet-monitoring frequency. The association was directionally reproduced in the external cohort, although the effect estimate was modest. Prospective studies with standardized platelet-sampling schedules are needed before clinical implementation.