Prognostic Score Model for 30-Day Mortality in Patients with Acute Pulmonary Embolism Presenting to the Emergency Department.

Background/Objectives: Early risk stratification is essential in pulmonary embolism (PE), but a simple tool integrating routinely available clinical and laboratory variables is lacking. We aimed to develop a simple score for predicting 30-day mortality in patients presenting to the emergency department (ED) with PE. Methods: We conducted a multicenter study in three hospitals in Korea. The score was derived at the largest hospital using least absolute shrinkage and selection operator logistic regression with bootstrap stability selection, and validated in the pooled cohort from the remaining two hospitals. Discrimination was assessed using the area under the receiver operating characteristic curve (AUROC) and compared with PESI and sPESI. Calibration was assessed using the Brier score and calibration parameters. Results: Among 2446 patients, 1753 were included in the derivation cohort and 693 in the validation cohort. The final score (3C score) assigned one point each for history of cancer, international normalized ratio ≥1.15, and C-reactive protein ≥50 mg/L. In the validation cohort, the AUROC was 0.767 (95% CI, 0.703-0.822) for 30-day mortality, compared with 0.748 for PESI and 0.725 for sPESI. 30-day mortality increased from 2.4% (score 0) to 34.4% (score 3). A score of 0 identified 42.7% of patients as low risk, with a negative predictive value of 97.6%. Calibration was acceptable (Brier score, 0.077; calibration slope, 1.098). Conclusions: The 3C score showed discrimination comparable to PESI and sPESI and identified a substantial subgroup with low risk. Its simplicity may facilitate ED risk assessment, although further validation is required before clinical implementation.