Prevalence and Risk Factors of Pulmonary Arterial Hypertension in Interstitial Lung Diseases: A Cross-sectional Study

Introduction: Interstitial Lung Diseases (ILD) is associated with inflammatory and/or fibrotic changes in the lungs. Pulmonary Arterial Hypertension (PAH) is a complication of many end-stage lung diseases due to the re-modelling of pulmonary vasculature associated with hypoxia leading to pulmonary vascular resistance. The Association of PAH in ILD contributes significantly to high morbidity and mortality. ILD being a progressive disease it is difficult to predict when the PAH will set in.

Aim: To assess the clinical and radiological profiles of patients with ILD and to associate these with the severity of PAH.

Materials and Methods: The present cross-sectional study was conducted in the Department of Respiratory Medicine at GSL Medical College on 23 patients with ILD from 1st October 2019 to 31st august 2021, in GSL medical college and hospital, Andhra Pradesh. Each patient was subjected to chest X-ray (CXR), Electrocardiogram (ECG), and 2-Dimensional Echocardiogram (2D ECHO). Evidence of PAH in any one investigation was considered. In ECG reports evidence of right ventricular enlargement (R>S in V1/V2 and right axis deviation >110 degrees, R=11 mm) was considered as PAH. CXR showing dilatation of the pulmonary artery with an increased cardiothoracic ratio was considered as PAH. A 2-D ECHO was performed to estimate the right arterial pressure and evidence of pulmonary arterial systemic pressure of >40 mmHg was considered as PAH. All the data were statistically analysed by using IBM Statistical Package for Social Sciences (SPSS) version 20.0.

Results: Fifty-two percent of the population constituted females, and the mean age of the whole population was 59.7±14.4 years and the majority of them (65%) belonged to upper lower socioeconomic class. Usual Interstitial Pneumonia (UIP) was the most common pattern observed accounting for 57%. Prevalence of PAH was 65% and a longer duration of symptoms, 57% of the population had grade 3 of Modified Medical Research Council (MMRC) and 52.17% covered less than 200 meters in the 6-Minute Walk Test (6MWT). Oxygen desaturation after 6MWT was observed to be the contributing factor for the development of severe pulmonary hypertension in ILD patients.

Conclusion: Factors like delayed seeking of medical care, co-morbidity like hypertension, higher grades of dyspnoea at the time of presentation, shorter 6MWD, and post-walk oxygen saturation were found to be predictors of pulmonary artery hypertension in patients with ILD. Early recognition of these risk factors in patients with ILD and the prompt treatment of the disease can reduce the development of severe PAH.