# Platelet-to-neutrophil ratio and in-hospital mortality in pneumonia patients receiving glucocorticoid therapy: a multicenter retrospective cohort study

## TL;DR

Lower platelet-to-neutrophil ratio (PNR) at admission is linked to higher mortality in pneumonia patients on glucocorticoid therapy, suggesting PNR could help identify high-risk patients.

## Contribution

This study is the first to explore the prognostic value of PNR in pneumonia patients receiving glucocorticoid therapy.

## Key findings

- Lower PNR tertiles correlated with significantly higher 30- and 90-day in-hospital mortality rates.
- Each standard deviation increase in PNR reduced mortality risk by 50% at 30 days and 58% at 90 days.
- PNR showed better predictive performance than platelet or neutrophil counts alone.

## Abstract

Pneumonia remains a leading cause of global mortality. Patients receiving glucocorticoid therapy represent a particularly vulnerable subgroup due to therapy-induced immunosuppression, which complicates diagnosis and worsens prognosis. The platelet-to-neutrophil ratio (PNR), a composite hematologic index, has shown prognostic utility in various diseases, but its value in glucocorticoid-treated pneumonia patients remains unexplored.

This multicenter retrospective cohort study utilized data from 686 hospitalized pneumonia patients receiving systemic glucocorticoids, extracted from the Dryad database. The association between admission PNR and all-cause in-hospital mortality at 30 and 90 days was assessed using Cox proportional hazards models. Receiver operating characteristic curves were used to evaluate predictive performance.

In-hospital mortality within both 30 and 90 days decreased significantly with increasing PNR tertiles (Tertile 1 vs. Tertile 3: 37.55% vs. 9.61% for 30-day; 43.67% vs. 10.92% for 90-day). In fully adjusted models, each standard deviation increase in PNR was associated with a 50% reduction in 30-day in-hospital mortality [Hazard Ratio (HR) = 0.497, 95% CI 0.262–0.942] and a 58% reduction in 90-day in-hospital mortality (HR = 0.416, 95% CI 0.218–0.793). Compared to the lowest tertile, the highest PNR tertile was associated with a 76% lower risk of 30-day mortality (HR = 0.235, 95% CI 0.107–0.513) and an 82% lower risk of 90-day mortality (HR = 0.184, 95% CI 0.085–0.398). PNR demonstrated superior predictive ability (areas under the curve for 30-day: 0.707; 90-day: 0.713) compared to platelet or neutrophil count alone. Subgroup analysis revealed stronger associations in patients receiving high-dose glucocorticoids and those with diabetes or hypertension.

A lower PNR at admission is independently associated with increased short-term mortality in pneumonia patients receiving glucocorticoids. PNR, as a readily available biomarker, may facilitate early risk stratification and identify high-risk patients who could benefit from more aggressive management.