Nomogram-Based Mortality Prediction in Acute Pulmonary Embolism Using Inflammatory Biomarkers and the Simplified Pulmonary Embolism Severity Index

Background/Objectives: Pulmonary embolism (PE) remains a major cause of mortality, requiring rapid risk stratification. Widely used clinical tools such as the simplified Pulmonary Embolism Severity Index (sPESI) may not fully capture the disease’s inflammatory burden. This study aimed to evaluate the prognostic value of multiple inflammatory indices and to develop a clinically applicable nomogram integrating these indices with sPESI for mortality prediction in acute PE. Methods: This multicenter retrospective cohort study included 338 patients with acute PE. Ten inflammatory indices were calculated from admission laboratory data. The primary outcome was 12-month all-cause mortality; secondary outcomes were 30-day and 90-day mortality. Receiver operating characteristic analysis, multivariable Cox regression, and person-time analysis were performed. A composite inflammatory risk score (0–10) was developed, and a nomogram combining this score with sPESI was constructed. Internal validation used 1000 bootstrap resamples. Results: Overall mortality was 44.1%, with 41% of deaths occurring in the first 12 months. The red cell distribution width-to-albumin ratio (RAR) showed the highest discriminative performance (AUC = 0.755, 95% CI: 0.704–0.806). Each 1-point increase in the inflammatory risk score was independently associated with increased 30-day mortality (HR: 1.21, 95% CI: 1.10–1.34) and 90-day mortality (HR: 1.25, 95% CI: 1.15–1.36). The nomogram improved risk classification, particularly in patients with intermediate sPESI scores (1–2). The combined model achieved an AUC of 0.806 (95% CI: 0.761–0.851), with good calibration (Hosmer–Lemeshow p = 0.342). Platelet-to-lymphocyte ratio (PLR) did not show significant prognostic value. Conclusions: RAR is a strong, independent predictor of mortality in acute PE, providing incremental prognostic value beyond sPESI. The integrated nomogram enables more precise risk stratification and offers a practical, low-cost tool for bedside use.