Association of WPR with in-hospital mortality in patients with severe acute pancreatitis: a study based on the MIMIC-IV database

Background Severe acute pancreatitis (SAP) is a common critical emergency in clinical practice and carries an extremely high risk of mortality. WPR (white blood cell to platelet ratio), as a potential clinical indicator, has an unclear prognostic value in SAP patients. This study aimed to investigate the association between WPR and the risk of in-hospital mortality in patients with SAP. Methods This was a retrospective observational study based on the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. After applying the inclusion and exclusion criteria, 902 patients with SAP were ultimately enrolled. The optimal cutoff value of WPR was determined to be 0.065 using the maxstat package, and patients were divided into high-WPR and low-WPR groups accordingly. Cox proportional hazards models were used to evaluate the independent association between WPR and in-hospital mortality, and the results were presented in three models (crude model; Model 1 adjusted for age; Model 2 further adjusted for pH, lactate, acute renal failure, and continuous renal replacement therapy [CRRT]). In addition, restricted cubic splines (RCS), Kaplan–Meier survival curves, subgroup analyses, and mediation analyses were performed. Results Among the 902 patients included, 774 were in the survivor group and 128 in the non-survivor group. Multivariable Cox regression (Model 2) showed that the high-WPR group had a significantly higher risk of in-hospital mortality than the low-WPR group (HR = 1.369, 95% CI: 1.048–1.788, P = 0.0212). RCS analysis demonstrated a significant association between WPR and mortality risk in SAP (P-overall = 0.001). The Kaplan–Meier survival curves showed that the high-WPR group had significantly lower survival (P = 0.00032). Mediation analysis revealed that lactate and creatinine mediated 10.58% and 11.15% of the association, respectively. Conclusions WPR is an independent risk factor for in-hospital mortality in patients with SAP. Clinical monitoring of WPR levels may facilitate early identification of high-risk patients.