Screening for Pulmonary Hypertension in Interstitial Lung Disease: Preliminary Results from the PHINDER Study

INTRODUCTION: Interstitial lung disease (ILD) is frequently complicated by pulmonary hypertension (PH) resulting in reduced functional capacity, diminished quality of life, and increased mortality. However, standardized screening for PH in ILD is lacking, causing delays in diagnosis and treatment. PHINDER (NCT05776225) is a prospective multicenter study that aims to identify parameters for the detection of PH in ILD. METHODS: Data were collected prospectively in patients with ILD from predefined routine testing, including clinical, physiological, and imaging assessments. Precapillary PH was defined as mean pulmonary arterial pressure > 20 mmHg, pulmonary artery wedge pressure ≤ 15 mmHg, and pulmonary vascular resistance (PVR) > 2 Wood units (WU). Investigators estimated probability of precapillary PH based on noninvasive evaluations before confirmation by right heart catheterization (RHC). RESULTS: Preliminary results included 190 participants; 105 (55%) had precapillary PH and 26 (14%) had severe PH (PVR > 5 WU). Notable parameters associated with precapillary PH included supplemental oxygen use (OR 3.6, p = 0.004), diffusing capacity of the lung for carbon monoxide ([DLCO] OR 0.9, p = 0.005), forced vital capacity % to DLCO % ratio (OR 1.1, p = 0.008), tricuspid annular plane systolic excursion to right ventricular systolic pressure ratio (OR 0.8, p = 0.020), tricuspid regurgitant velocity (OR 4.4, p = 0.006), pulmonary artery (PA) enlargement (OR 10.6, p < 0.001), PA/aorta diameter ratio (OR 1.7, p = 0.004), and right to left ventricle diameter ratio (OR 1.5, p = 0.021). There was a trend toward higher likelihood of PH with higher clinician suspicion of PH before RHC, but gestalt-based assessment showed limited accuracy relative to hemodynamic confirmation (positive predictive value, 59%; negative predictive value, 68%; accuracy, 60%). CONCLUSIONS: Preliminary findings support the composite use of pulmonary function testing, lung imaging, and echocardiography to improve early detection of precapillary PH in ILD and guide structured screening strategies. The final data set from PHINDER will provide guidance on thresholds for continuous variables with application in diagnosing PH in ILD, facilitating the development of a validated evidence-based screening tool to aid the detection of PH in ILD. TRAIL REGISTRATION: NCT05776225.