Beyond IPF: Pulmonary Function Test Predictors of Echocardiographic Pulmonary Hypertension Across the Spectrum of ILD.

Abstract

Pulmonary hypertension (PH) is a common complication of interstitial lung disease (ILD), yet data on screening in heterogenous ILD populations are limited. We evaluated whether routinely measured pulmonary function test (PFT) parameters identify individuals with intermediate-to-high echocardiographic risk of PH. 432 ILD patients met inclusion criteria with an echocardiogram reporting peak tricuspid regurgitant velocity (TRV) and a PFT reporting diffusion impairment (DLCO) within 1 year (median interval, 39 days). Of these, 126 underwent right heart catheterization (RHC). Age- and sex- adjusted logistic regression assessed associations between %predicted forced vital capacity (FVC), %predicted DLCO, and FVC/DLCO ratio with intermediate-to-high echocardiographic PH probability (TRV > 2.8 m/s). Receiver operating characteristic curves evaluated diagnostic performance. The cohort included 28% systemic autoimmune rheumatic disease-associated ILD, 27% interstitial pneumonia with autoimmune features, and 6% idiopathic pulmonary fibrosis, with a mean age of 72% and 54% female. Lower FVC and DLCO were associated with higher odds of echocardiographic PH (OR 1.35, 95%CI 1.21-1.50; OR 1.50, 95%CI 1.36-1.73) and increases in FVC/DLCO ratio similarly predicted risk (OR 1.83, 95%CI 1.44-2.32). DLCO had the highest predictive ability (AUC 0.74, 95%CI 0.69-0.79) with an optimal cut-off of 42% (sensitivity 67%, specificity 74%). In patients who underwent RHC, TRV > 2.8 m/s correlated with mean pulmonary artery pressure (r = 0.55, 95%CI 0.42-0.66) and tripled the odds of confirmed PH (OR 3.75, 95%CI 2.25-6.24). In sum, severe diffusion impairment, regardless of fibrosis extent, may detect patients with ILD who warrant echocardiographic screening, specialty PH referral, and consideration of RHC.