Effect of pulmonary hypertension on survival in patients with idiopathic pulmonary fibrosis after lung transplantation: An analysis of the United Network of Organ Sharing registry

Background Pulmonary hypertension (PH) is a comorbidity associated with idiopathic pulmonary fibrosis (IPF). There is limited research regarding the effect on survival after lung transplantation (LTx). Methods To assess the effect of PH on survival in patients with IPF who received LTx, the United Network for Organ Sharing was queried for eligible patients with recorded mean (PA_mean) and systolic (PA_systolic) pulmonary artery pressure. The analysis was restricted to the post-lung allocation scoring system starting May 1, 2005, to provide a cohort receiving present-day therapies and management. The last update of the data set was July 6, 2012, so a cutoff date of July 6, 2011, was chosen to allow for the possibility of at least 1 year of follow-up. Thresholds of ≥25 and ≥35 mm Hg were chosen for PA_mean and PA_systolic, respectively, as indicators of PH. Results Of 23,951 LTxs in the UNOS data set, 2,542 met inclusion criteria, 1,234 (49%) with PA_mean ≥ 25 mm Hg and 1,680 (66%) with PA_systolic ≥ 35 mm Hg. PA_mean and PA_systolic were highly correlated, with an estimated correlation coefficient ρ = 0.93 (p < 0.001). Patients with PH (PA_mean ≥ 25 mm Hg or PA_systolic ≥ 35 mm Hg) tended to have higher ischemic times, lung allocation score values, forced vital capacity percentage predicted at LTx, and supplemental oxygen requirement at rest values. In addition, a larger proportion of patients with PH was African American, male, had diabetes, and received bilateral LTx compared with single LTx. Comparing PA_mean < 25 vs ≥ 25 mm Hg and PA_systolic < 35 vs ≥ 35 mm Hg, median survival in months was 60.4 (95% confidence interval [CI], 55.2-80.4) vs 61.4 (95% CI, 56.9-66.9; log-rank p = 0.876) and 57.6 (95% CI, 50.9-68.0) vs 64.3 (95% CI, 57.5-71.3; log-rank p = 0. 247), respectively. Hazard ratios for both definitions of PH from univariable and multivariable Cox proportional hazard models were close to 1 and none were statistically significant. Conclusions On the basis of our models and despite PH being prevalent, there is no strong evidence suggesting that PH significantly alters the risk of death in IPF patients after LTx.