Association between the glucose-to-platelet ratio and short-term and long-term all-cause mortality in critically ill patients with pneumonia: a retrospective cohort study.

Background: Pneumonia remains a leading cause of mortality among critically ill patients. Early and simple biomarkers for risk stratification are still needed. The glucose-to-platelet ratio (GPR), integrating metabolic stress and hematological alterations, has not been fully evaluated in critically ill patients with pneumonia. Therefore, this study aimed to evaluate the association between the GPR and both short-term and long-term all-cause mortality in critically ill patients with pneumonia. Methods: This retrospective cohort study was conducted using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Adult patients admitted to the intensive care unit (ICU) with a diagnosis of pneumonia were included regardless of subtype. GPR was calculated as blood glucose divided by platelet count (PLT) measured within the first 24 hours of ICU admission. The primary outcome was 30-day all-cause mortality, and the secondary outcome was 360-day all-cause mortality after ICU admission. Cox proportional hazards models were used to evaluate the association between GPR and mortality, adjusting for potential confounders. Restricted cubic spline (RCS) analyses were performed to assess potential nonlinear relationships. Results: A total of 9,817 critically ill patients with pneumonia were included. During follow-up, 2,004 (20.4%) and 3,860 (39.3%) patients died within 30 and 360 days, respectively. After full adjustment for demographics, comorbidities, severity scores, and laboratory parameters, a higher GPR remained independently associated with increased risks of both 30-day [hazard ratio (HR) per unit increase: 1.12, 95% confidence interval (CI): 1.10-1.15] and 360-day mortality (HR: 1.12, 95% CI: 1.10-1.14). Compared with the lowest tertile, patients in the highest GPR tertile had significantly increased mortality risks (30-day: HR 1.37, 95% CI: 1.23-1.53; 360-day: HR 1.23, 95% CI: 1.14-1.33). RCS analyses suggested a mild non-linear association for 30-day mortality, whereas an approximately linear relationship was observed for 360-day mortality. Conclusions: Higher GPR is independently associated with increased short-term and long-term all-cause mortality among critically ill patients with pneumonia. GPR may represent a simple and readily available marker for early risk stratification in this population.