Background: Both idiopathic pulmonary arterial hypertension (IPAH) and pulmonary arterial hypertension (PAH) related to connective tissue diseases (CPAH) are classified in the group of PAH disorders. However, CPAH has a particularly worse prognosis than IPAH. Few studies have compared the clinical, functional and hemodynamic profiles of IPAH and CPAH.
Methods: We performed a retrospective cohort study of patients with IPAH or CPAH. Demographic characteristics, functional status (FE), pulmonary function test and hemodynamic values at the time of diagnosis were compared between the two etiologies. Global cumulative survival rates free from transplantation (SFT) and survival according to date of diagnosis were analyzed.
Results: Despite similar PAH severity, patients with CPAH showed a more severe baseline impairment of 6-minute walking test (6MWT) (307 +/- 116 m vs 378 +/- 101 m) and diffusion capacity of the lung for carbon monoxide (DLCO) (57 +/- 25% vs 75 +/- 30% of predicted) than IPAH (p < 0.01). Survival rates at 1, 3 and 5 years of follow-up were 87%, 71% and 63% for IPAH, and 70%, 53% and 42% for CPAH, respectively (p < 0.05). IPAH showed better survival when treatment was started after Year 2000 (p = 0.01). However, CPAH showed a poorer prognosis than IPAH in the more recent era (p < 0.05). CPAH (hazard ratio [HR] = 2.03), DLCO <80% (HR = 1.98) and treatment before Year 2000 (HR = 2.27) were associated with an independent increased risk of death or transplantation.
Conclusions: Despite similar functional and hemodynamic severity, patients with CPAH showed a more severe baseline impairment of 6MWT and DLCO and worse overall prognosis than IPAH. Both IPAH and CPAH survival improved in the current era. Nevertheless, CPAH still showed a poorer prognosis than IPAH.