Development of pulmonary hypertension in a high-risk population with systemic sclerosis in the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma (PHAROS) cohort study

ObjectivesPHAROS registry is a prospective longitudinal cohort study to understand the natural history of pulmonary hypertension (PH) in systemic sclerosis (SSc).Methods“At-risk” pulmonary arterial hypertension (PAH) is defined by these entry criteria: echocardiogram (echo) systolic pulmonary arterial pressure (sPAP) >40 mmHg, diffusion lung capacity of carbon monoxide (DLco) <55% predicted, or ratio of percentage forced vital capacity (FVC)/percentage DLco >1.6, as measured by pulmonary function testing (PFT). Patients were followed up annually and right heart catheterization (RHC) performed if PH was suspected. We used descriptive statistics and Kaplan–Meier estimate of time to PH diagnosis.ResultsA total of 251 “at-risk” subjects were enrolled between 2005 and 2012 and followed up for mean of 2.5 ± 1.2 years. The mean age at entry was 56.7 ± 11.0 and disease duration was 9.9 ± 8.7 years.Overall, 82 patients had RHC, and 35 were confirmed to have new PH. There were no differences in age, gender, SSc subtypes, antibodies, and disease duration between the “at-risk” and new PH groups. Using Kaplan–Meier survival, the time to PH was 10% at 2 years, 13% at 3 years, and 25% at 5 years. Most new PH patients at entry met the PFT criteria (76%), had significantly higher sPAP (p = 0.013), had shorter 6-min walk distance, and had exercise-induced hypoxia (p = 0.003) than “at-risk” PAH group.ConclusionsA low DLco, high FVC/DLco, exercise-induced hypoxia and entry echo sPAP > 40 were strongly associated with future PH, though RHC was necessary to confirm PH. This ongoing prospective study confirms that these high-risk factors do predict future PH.