BACKGROUND: Pulmonary hypertension is a common complication of interstitial lung disease. This study was conducted to retrospectively analyze the incidence of pulmonary hypertension among interstitial lung disease patients and the correlation between systolic pulmonary artery pressure (PASP) and pulmonary functions. We also intended to investigate whether antinuclear antibody (ANA) could be an effective indicator of pulmonary hypertension.

MATERIAL AND METHODS: There were 182 patients diagnosed with interstitial lung disease through high-resolution computed tomography (HRCT). Pulmonary hypertension was defined as an increase of mean pulmonary arterial pressure (PAPm) ≥25 mmHg (~PASP ≥40 mmHg) at rest. Severe pulmonary hypertension was defined as PAPm ≥35 mmHg. There were 104 cases including in this study. There were 67 cases from the ANA positive (ANA+) group and 37 cases from the ANA negative (ANA–) group. All study patients had pulmonary function tests, which included the measurements of maximal voluntary ventilation (MVV), residual volume (RV), total lung capacity (TLC), forced expiratory volume (FVC), vital capacity (VC), and diffusing capacity of the lungs for carbon monoxide (DLCO).

RESULTS: The pulmonary hypertension incidence in the study cohort was 25%, and the severe pulmonary hypertension incidence was 6.48%. The incidence of pulmonary hypertension in ANA+ cases was 22.22%. The incidence of pulmonary hypertension in the ANA– cases was 32.14%. The lung function test results showed moderate relationships between DLCO, FVC%, VC%, and PASP; no relationship between MVV, FEV1/FVC%, RV/TLC, and PASP; minimum relationship between FVC%, VC%, and PASP in the ANA+ group; and moderate relationship between FVC%, VC%, and PASP in the ANA– group.

CONCLUSIONS: Pulmonary hypertension occurred in 25% of the 182 interstitial lung disease patients and was negatively associated with deteriorated lung functions (specifically VC%, FVC%, and DLCO parameters). ANA level was not associated with the prognosis of pulmonary hypertension of patients with interstitial lung disease, and it did not significantly affect the correlation between PASP and pulmonary functions. Thus, ANA level did not seem to be a necessary indicator of pulmonary hypertension, and a more effective treatment method for pulmonary hypertension of patients with interstitial lung disease is urgently needed.

Keywords: Lung Diseases, Interstitial, Persistent Fetal Circulation Syndrome, Respiratory Function Tests, Antibodies, Antinuclear, Blood Pressure, Cohort Studies, Forced Expiratory Volume, Hypertension, Pulmonary, Vital Capacity