Higher Platelet-to-White Blood Cell Ratio Linked to Survival in HFpEF

A higher platelet-to-white blood cell ratio measured early in intensive care was associated with lower 28-day mortality among critically ill adults with heart failure with preserved ejection fraction (HFpEF), according to a retrospective cohort study. The finding applied to patients who survived and remained in the ICU for at least 24 hours, and the researchers said the ratio may offer an accessible complementary risk signal derived from routine blood counts.

The study used MIMIC-IV version 3.1 for model development and the main analyses, while an external cohort from eICU version 2.0.1 was used for exploratory assessment. The researchers defined the platelet-to-white blood cell ratio, or PWR, from the first platelet and white blood cell measurements recorded within 24 hours after ICU admission. The primary endpoint in MIMIC-IV was 28-day all-cause mortality.

The MIMIC-IV cohort included 5,774 adult ICU patients with HFpEF, of whom 632 died within 28 days, corresponding to 10.95% mortality. After adjustment for measured clinical and laboratory factors, mortality risk was lower in patients with higher PWR values than in the lowest quartile. Compared with the first quartile, the adjusted hazard ratios were 0.79 for the second quartile, 0.58 for the third and 0.61 for the fourth, with confidence intervals excluding 1.0 for all three comparisons. The P value for the trend across quartiles was below 0.001.

Restricted cubic spline analyses supported a nonlinear relationship between PWR and mortality. In other words, the association was not simply a constant reduction in risk for every additional increase in the ratio. The study therefore treated PWR as a variable whose relationship with outcome may differ across its range, rather than assuming that each unit increase had the same effect throughout the distribution.

The investigators also compared five machine-learning approaches with conventional statistical modelling. A random forest model had the highest discrimination in an internal holdout test set, achieving an area under the receiver operating characteristic curve, or AUROC, of 0.813 and an area under the precision-recall curve, or AUPRC, of 0.387. A conventional unpenalized logistic regression using the same 15 predictors produced an AUROC of 0.792 and an AUPRC of 0.389, indicating only a modest difference between the modelling approaches in the reported comparison.

For the exploratory external assessment, the locked model specification was refitted using the complete MIMIC-IV cohort and applied to 685 patients in eICU. The eICU analysis used in-hospital mortality, observed in 13.3% of that cohort, because the database did not provide uniform post-discharge follow-up for determining 28-day mortality. The model achieved an AUROC of 0.767, with a 95% confidence interval of 0.715 to 0.817. Because the outcome differed from the primary MIMIC-IV endpoint, the researchers described this analysis as exploratory rather than an endpoint-matched validation.

Although adding a nonlinear PWR term improved full-sample model fit, its cross-validated predictive performance changed only slightly, with the AUC increasing from 0.763 to 0.764. Calibration remained comparable, and decision-curve analysis did not show a consistent gain in net benefit. These results suggest that PWR was associated with prognosis independently, but its added predictive value beyond a comprehensive set of severity indicators was limited.

The findings are observational and do not establish that changing the platelet-to-white blood cell ratio would alter survival. The analysis also depended on the selected ICU databases, available measurements and the completeness of adjustment for confounding. In addition, the association was demonstrated specifically in critically ill patients with HFpEF who survived and stayed in the ICU for at least 24 hours, and the exploratory external cohort used a different mortality endpoint. The researchers’ conclusion was correspondingly cautious: higher PWR may provide a practical supplementary risk marker, but it did not substantially improve prediction when incorporated into the broader clinical model.

Subject of Research: Prognostic association between early platelet-to-white blood cell ratio and mortality in critically ill patients with HFpEF

Article Title: Platelet to white blood cell ratio and short term mortality in critically ill patients with HFpEF

Article References: Cao, Z., Chen, Z., Wei, Y., Liu, S., Li, Y., Liu, Y., & Dong, G. (2026). Platelet to white blood cell ratio and short term mortality in critically ill patients with HFpEF. Scientific Reports. https://doi.org/10.1038/s41598-026-75774-9

Image Credits: AI Generated

DOI: 10.1038/s41598-026-75774-9

Keywords: HFpEF, critical care, platelet-to-white blood cell ratio, mortality, blood counts, risk prediction, machine learning, retrospective cohort, Platelet, white, blood, cell