Interaction of pre-transplant recipient characteristics and renal function in lung transplant survival

Background: There has been little investigation into the potential interaction of recipient characteristics with the association of pre-transplant renal functions and survival after lung transplantation. In this study we tested the hypothesis that association of pre-transplant renal function and post-transplant mortality varies among recipient subgroups. Methods: We queried the United Network for Organ Sharing (UNOS) database for adult patients (≥18 years of age) undergoing lung transplantation between May 2005 and March 2015. The study population (n = 15,540) was split into 3 groups (90 to 150, 60 to 89.9 and 30 to 59.9 ml/min/1.73 m²) based on the estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration equation) at the time of listing. We utilized multivariable inverse probability weighted Cox proportional hazard models to compare the association of glomerular filtration rate (GFR) groups with mortality among recipient subgroups. Results: Overall, there was an independent and graded inverse association between the estimated GFR (eGFR) and mortality, with the hazard of mortality significantly rising with listing eGFR <60 ml/min/1.73 m². The association between low eGFR and mortality was more consistent and stronger for older (>45 years), non–African-American and non-diabetic patients as well as those with low lung allocation score (LAS <40). Among the diagnosis groups, patients with vascular diseases had the strongest association between low eGFR and poor survival. Sensitivity analyses conducted using an alternate equation to estimate the GFR (Modification of Diet in Renal Disease) supported these associations. Conclusions: Prognostic significance of pre-transplant renal functions varies significantly among recipient subgroups. It may be appropriate to develop a customized approach toward assessing and interpreting renal function to determine transplant candidacy.