An exploratory model for short-term risk stratification in intermediate-high-risk pulmonary embolism running head: The STAMP score

Background Intermediate-high-risk pulmonary embolism (PE) patients are at increased risk of sudden clinical deterioration within the first hours after symptom onset. Objective We aimed to develop and validate a practical prediction model and scoring system for identifying intermediate-high-risk PE patients at elevated risk of 48-hour clinical deterioration after symptom onset. Methods The STAMP score was developed using data from 450 intermediate-high-risk PE patients enrolled in the Italian Pulmonary Embolism Registry (ClinicalTrials.gov: NCT01604538), incorporating demographic, clinical, and imaging variables identified through multivariable analyses. Results A derivation cohort of 270 patients was used to create the score, which was subsequently validated in 180 patients. In the derivation cohort, multivariate analysis identified five independent predictors of 48-hour clinical deterioration: age ≥65 years (1 point), chest pain (1 point), syncope (2 points), TAPSE/PASP ≤0.33 (2 points), and mean arterial pressure (MAP) ≤81.5 mmHg (2 points). Based on the total score, patients were stratified into low (0–2 points), intermediate (3–5 points), and high (6–8 points) probability groups, with event rates significantly increasing across categories (p<0.001) in both derivation and validation cohorts. The STAMP score demonstrated good diagnostic performance, with areas under the curve of 0.86 and 0.85, C-statistics of 0.81 and 0.80, and Hosmer–Lemeshow p-values of 0.47 and 0.45, respectively. Conclusions The STAMP score is a novel, simple, and accurate tool that enhances early risk stratification in intermediate-high-risk PE patients, improving the identification of those at greatest risk of 48-hour clinical deterioration.