Prognostic impact of coexisting lung disease in patients with pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive disorder of the pulmonary vasculature. A subset of patients with PAH exhibit concomitant lung disease (LD); nonetheless, the clinical significance of this overlap remains uncertain. METHODS: We retrospectively compared patients diagnosed with PAH and those with group 3 pulmonary hypertension (G3PH). Baseline chest computed tomography scans were reviewed, and the patients with PAH were stratified into two subgroups: without LD (PAH-no LD) and with LD (PAH-LD). Clinical characteristics and outcomes were compared among the three groups. RESULTS: Overall, 158 patients were included (37 PAH-no LD, 39 PAH-LD, and 82 G3PH). Compared with the PAH-no LD group, patients with PAH-LD were older, had worse functional capacity, and demonstrated shorter six-minute walk distances, similar to those in the G3PH group. The 1-, 3-, and 5-year survival rates of patients with PAH-LD were lower than those of individuals with PAH-no LD, but comparable to those of patients with G3PH. In multivariable Cox regression analysis restricted to patients with PAH, concomitant LD was associated with increased mortality after adjustment for age (age-adjusted hazard ratio, 4.80; 95% confidence interval, 1.15-19.99). Respiratory failure accounted for approximately 40% of deaths in the PAH-LD and G3PH groups, but not in the PAH-no LD group. CONCLUSIONS: In this cohort, nearly half of the patients with PAH had coexisting LD, which was associated with impaired exercise capacity and poor prognosis, comparable to that of G3PH. Therefore, early identification and tailored management of this high-risk PAH phenotype is necessary.