Pulmonary hypertension in interstitial lung disease: prevalence, prognosis and 6 min walk test

Pulmonary hypertension (PH) is an important complication to interstitial lung disease (ILD). The aim of the present study was to investigate the prevalence and impact of PH on prognosis and exercise capacity in ILD patients.

212 ILD patients were screened for PH by echocardiography. Criteria for PH were either a tricuspid pressure regurgitation gradient >40 mmHg, a tricuspid annular plane systolic excursion <1.8 cm or right ventricular dilatation. If possible, PH was confirmed by right heart catheterisation. Pulmonary function tests and 6 min walk tests (6MWT) were performed.

29 patients (14%) had PH, 16 (8%) had mild and 13 (6%) had severe PH (mean pulmonary artery pressure ≥ 35 mmHg). Compared to patients without PH, lung function parameters were lower in PH patients, a larger proportion had idiopathic pulmonary fibrosis (IPF) (41 vs 21%, p = 0.006), and the hazard ratio for death was 8.5 (95% CI: 4-17). After correction for lung function parameters and the presence of IPF, 6MWT was significantly lower in patients with PH compared to non-PH patients (difference ± SEM: 58 ± 22 m, p = 0.01).

PH occurred in 14% of a cohort of patients with ILD and was associated to IPF and lower lung function parameters. Mortality was markedly higher in PH patients, and the presence of PH reduced 6MWT independently of lung function and the presence of IPF. The present results emphasize the need for intensified treatment of patients with ILD and PH.