A Survey of Referral Rates for Lung Transplant Assessment in Patients with Interstitial Lung Disease Meeting Pulmonary Function Criteria

Abstract

<h3>Purpose</h3> Progressive interstitial lung diseases (ILD) unresponsive to medical therapy often require referral for lung transplantation (LTx) assessment, as this can prolong quality-of-life and survival. Ideal timing for referral for LTx remains challenging, with late-referral associated with significant morbidity and mortality. Among other criteria, ILD patients should be considered for LTx if forced vital capacity (FVC) is less than 80% or diffusion capacity for carbon monoxide (DLCO) is less than 40%. However, data on referral rates are lacking. The objective of this study was to evaluate referral rates and identify possible barriers associated with non-referral of these patients. <h3>Methods</h3> A single-center, retrospective cohort study of ILD patients who had pulmonary function test (PFT) performed between January 1, 2014, and January 1, 2020. Patients with FVC<80% or a DLCO<40% were included in the study. Patients with absolute contraindications to LTx were excluded. Referral rates were computed, and patients' characteristics were compared between referred and non-referred subjects. Potential predictors of survival were assessed using Kaplan-Meier and Cox proportional hazards models. <h3>Results</h3> Out of 114 ILD patients who met PFT criteria for referral to LTx, only 35 were referred (30.7%), and seven have undergone LTx. Median time from PFT to referral for assessment was 255 days [IQR 35.5-1077.5], while median time from referral to LTx was 88.5 days [IQR 59.5-142.8]. Referred patients were younger [58.4 vs. 66.8, P=0.003], had lower FVC [47 vs. 62.1, P<0.001] and DLCO [24.2 vs. 36.5, P<0.001], and a higher rate of pulmonary hypertension [67.7% vs. 43.8%, P=0.04]. Lower FVC and higher GAP index (a clinical prediction tool used to estimate prognosis) were associated with mortality [HR=0.96, CI 0.95-0.98 P=0.001 and HR=1.97, CI 1.45-2.67 P<0.001 respectively]. There was no difference in mortality between the two groups. <h3>Conclusion</h3> There appears to be under-referral of patients with ILD who are potential LTx candidates. Late referral is associated with markers of severe disease. These patients have higher mortality rates and often miss the window of opportunity for LTx, and should be referred for assessment as early as possible. Further study is suggested to replicate these findings in other transplant centers and internationally.