Mean pulmonary arterial pressure as a prognostic indicator in connective tissue disease associated with interstitial lung disease: a retrospective cohort study

BACKGROUND Pulmonary hypertension (PH) can develop in connective tissue disease associated interstitial lung disease (CTD-ILD), and contributes to increased morbidity and mortality. However, except for systemic sclerosis and mixed connective tissue disease, the impact of mean pulmonary arterial pressure (MPAP) on survival in CTD-ILD has not been sufficiently elucidated. We hypothesized that pulmonary arterial pressure may be a prognostic factor in CTD-ILDs regardless of the kind of CTD. METHODS We evaluated the survival impact of MPAP, which is measured using right heart catheterization, on survival of patients with CTD-ILD with various CTD backgrounds. We retrospectively analyzed data of consecutive CTD-ILD patients undergoing a pulmonary function test and right-heart-catheterization at the initial evaluation. RESULTS We studied 74 patients (33 men and 41 women, mean age 62.8 ± 9.6, 24 with rheumatoid arthritis, 14 with systemic sclerosis, 14 with polymyositis/dermatomyositis, 11 with primary Sjögren's syndrome, and 11 with other diagnoses). Six patients exhibited pulmonary hypertension (MPAP ≥ 25 mmHg), and 16 (21.6 %) had mild elevation of MPAP (≥20 mmHg). The mean MPAP was 17.2 ± 5.5 mmHg. We did not observe a significant difference in MPAP among various CTDs. A univariate Cox proportional hazard model showed that MPAP has a significant impact on survival, while the type of CTD did not contribute to survival in our cohort. A multivariate Cox proportional hazard model showed MPAP (HR = 1.087; 95 % CI 1.008-1.172; p = 0.030) to be the sole independent determinant of survival. CONCLUSIONS Mild elevation of MPAP is relatively common in CTD-ILD patients with various CTD backgrounds. A higher MPAP at the initial evaluation was a significant independent predictor of survival in CTD-ILD. MPAP evaluation provides additional information on disease status and will help physicians predict mortality in CTD-ILD.