1771P - Performance of the ‘4S rule’ to predict short-term outcomes in cancer outpatients with unsuspected pulmonary embolism

The diagnosis of incidental or unsuspected pulmonary embolism (PE) in cancer outpatients undergoing scheduled CT-scans is a challenge in daily oncological practice. The aim of this study was to assess the performance of the ‘4S rule’ (Setting, Suspicion, Signs and Symptoms) as a PE risk-assessment model in this setting. We assessed consecutive patients with cancer-associated PE from an ongoing multicenter observational registry (2005-2018). Patients were classified as presenting ‘Truly asymptomatic unsuspected PE’ (TAUPE) according to the ‘4S rule’ (EurRespir J 2017;49(1):1600282 and EurRespir J 2017;49(1):1602225) that includes the following variables: (1) outpatient Setting at PE diagnosis; (2) no Suspicion of PE; (3) vital Signs within normal limits including blood pressure >100mmHg, heart rate 95%; and (4) absence of PE Symptoms. Short-term outcome measures included: all-cause and PE-related mortality within 30 days after the index PE. We evaluated a total of 617 patients (61.6% male; median age 65+11.4 years) including 207 (33%) with TAUPE, 284 (47%) with ‘acute suspected PE’ and 126 (20%) with ‘unsuspected PE with symptoms’. Most patients (79%) had metastatic cancer and nearly half (47%) were on chemotherapy. The PE was incidentally found in 54% of the cohort. The most frequent tumors were: 32% lung, 14% colorectal, 13% urological, and 12% upper gastrointestinal. All-cause 30-day mortality occurred in 95 patients (15% of the cohort) and 12 cases presented PE-related mortality (2% of the cohort). Patients with TAUPE had lower all-cause 30-day mortality compared to non-TAUPE cases (3% vs. 22%; p