Prediction of pulmonary hypertension in idiopathic pulmonary fibrosis

Abstract

Background: Reliable, noninvasive approaches to the diagnosis of pulmonary hypertension in idiopathic pulmonary fibrosis are needed. We tested the hypothesis that the forced vital capacity to diffusing capacity ratio and room air resting pulse oximetry may be combined to predict mean pulmonary artery pressure (MPAP) in idiopathic pulmonary fibrosis.

Methods: Sixty-one idiopathic pulmonary fibrosis patients with available right-heart catheterization were studied. We regressed measured MPAP as a continuous variable on pulse oximetry (SpO(2)) and percent predicted forced vital capacity (FVC) to percent-predicted diffusing capacity ratio (% FVC/% DL(co)) in a multivariable linear regression model.

Results: Linear regression generated the following equation: MPAP=-11.9+0.272 x SpO(2)+0.0659 x (100-SpO(2))(2)+3.06 x (% FVC/% DL(co)); adjusted R(2)=0.55, p<0.0001. The sensitivity, specificity, positive predictive and negative predictive value of model-predicted pulmonary hypertension were 71% (95% confidence interval (CI): 50-89%), 81% (95% CI: 68-92%), 71% (95% CI: 51-87%) and 81% (95% CI: 68-94%).

Conclusions: A pulmonary hypertension predictor based on room air resting pulse oximetry and FVC to diffusing capacity ratio has a relatively high negative predictive value. However, this model will require external validation before it can be used in clinical practice.

Figure 1

MPAP, mean pulmonary artery pressure; SpO₂, resting room air pulse oximetry; % FVC/% DL_co, percent predicted forced vital capacity/percent predicted diffusing capacity ratio.