Predictors of severe pulmonary hypertension in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease with a poor prognosis. The median survival after diagnosis does not exceed 2 – 3 years. One of the most significant complications of IPF is pulmonary hypertension (PH), the incidence of which is 20 – 84% and increases with the disease advancement.

The aim of the study was to comparatively analyze the clinical, functional and echocardiographic characteristics of patients with IPF depending on the degree of PH and to evaluate the diagnostic value of non-invasive parameters for detecting severe PH.

Methods. The observational study included patients (n = 121; median age – 69 years) with verified IPF. Depending on the pulmonary artery systolic pressure (PASP), the patients were divided into 3 groups. Group 1 (n = 35) included patients without PH (PASP < 35 mmHg). Group 2 (n = 59) included individuals with moderate PH (PASP 35 – 59 mmHg). Group 3 (n = 27) included patients with severe PH (PASP ≥ 60 mmHg). Clinical data, Charlson Comorbidity Index, 6-minute walk test (6-MWT), spirometry, diffusing capacity of the lungs for carbon monoxide (DLCO), high-resolution computed tomography (HRCT), and transthoracic echocardiography were assessed. Diagnostic accuracy was determined using ROC analysis, and the association with severe PH was determined using univariate and reduced multivariate logistic regression.

Results. As PASP increased, the incidence of cardiovascular events (26% vs 53% vs 74%, respectively; p < 0.001) and chronic heart failure (23% vs 47% vs 70%, respectively; p < 0.001) also grew, dyspnea progressed (modified Medical Research Council dyspnea scale – mMRC – 4 points: 8.6% vs 25% vs 41%, respectively; p = 0.049), desaturation rose during 6-MWT (7% vs 9% vs 12%, respectively; p = 0.002), and the right heart chambers dilated (the tricuspid annular systolic excursion (TAPSE) / PASP ratio was 0.697 vs 0.477 vs 0.317, respectively; p < 0.001). Spirometry parameters and DLCO did not differ between the groups. The degree of desaturation during the 6-MWT had the highest diagnostic value for detecting severe PH (AUC = 0.721: p = 0.005; sensitivity – 80%, specificity – 64% at the threshold > 9%). In the reduced multivariate model, desaturation remained the only independent predictor of severe PH (odds ratio – 1.237; 95% confidence interval – 1.086 – 1.437; p = 0.003).

Conclusion. Desaturation > 9% during the 6-MWT serves as a reliable non-invasive criterion for selecting patients with IPF for in-depth examination to detect severe

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