EXPRESS: Validation of a claims-based algorithm to identify patients with chronic thromboembolic pulmonary hypertension using electronic health record data.

This study aimed to validate an algorithm developed to identify chronic thromboembolic pulmonary hypertension (CTEPH) among patients with a history of pulmonary embolism. Validation was halted because too few patients had gold-standard evidence of CTEPH in the administrative claims/electronic health records database, suggesting that CTEPH is underdiagnosed.