Feasibility of a screening algorithm for chronic thromboembolic pulmonary hypertension: The OSIRIS study.

Introduction: Chronic thromboembolic pulmonary hypertension (CTEPH) is a long-term sequel to pulmonary embolism (PE) whose incidence varies according to different published studies. We have carried out this study to determine its incidence within 2 years after index pulmonary embolism and to study limitations to an early diagnosis.

Material And Methods: OSIRIS is a multicentre, longitudinal cohort study. Patients were followed for 3, 6, 12, and 24 months after pulmonary embolism using a structured three-step algorithm. A physician-centered questionnaire at least one positive response in a screening proceeded to the second step, transthoracic echocardiography. The third step consisted of ventilation/perfusion lung scintigraphy and right heart catheterisation. A transthoracic echocardiography was performed in patients without positive response in the screening questionnaire after 2 years. CTEPH diagnosis required haemodynamic confirmation by right heart catheterisation and mismatched perfusion defects on lung scintigraphy.

Results: A total of 1191 patients were enrolled in 18 Spanish hospitals. Cumulative CTEPH incidence after 2-years PE was: 2.49 % (95 % CI: 1.68-3.56) and the incidence rate of CTEPH was 1.1 cases per 1000 person-months (95 % CI: 0.725; 1.60). The CTEPH algorithm presented a lack of adherence of 29 %; patient and physician preferences posed barriers to the triage algorithm The screening questionnaire, in patients who completed the follow-up, shows a specificity of 91.3 % (89.0-93.2 %) and negative predictive value of 99.4 % (98.4-99.8 %)..

Conclusions: OSIRIS provides practiced clinical based data on the chronic thromboembolic pulmonary hypertension incidence and identified barriers to the implementation of a 3-step triage algorithm for its detection.

Clinical Trial Registration: clinicaltrials.gov identifier: NCT03134898.