Measurement of glomerular filtration rate in lung transplant recipients highlights a dramatic loss of renal function after transplantation

Abstract

Background: Chronic kidney disease (CKD) after lung transplantation (LT) is underestimated. The aim of the present study was to measure the loss of glomerular filtration rate (GFR) 1 year after LT and to identify the risk factors for developing Stage ≥3 CKD.

Methods: LT patients in the University Hospital of Lyon had a pre- and post-transplantation measurement of their GFR (mGFR), and GFR was also estimated using the Chronic Kidney Disease Epidemiology Collaboration equation.

Results: During the study period, 111 patients were lung transplant candidates, of which 91 had a pre-transplantation mGFR, and 29 had a mGFR at 1 year after LT. Six patients underwent maintenance haemodialysis after transplantation. Mean mGFR was 106 mL/min/1.73 m² before LT and 58 mL/min/1.73 m² 1 year after LT (P < 0.05) with a mean loss of 48 mL/min/1.73 m² per patient. The risk of developing Stage ≥3 CKD after LT was higher in patients with lower pre-LT mGFR (odds ratio for each 1 mL/min/1.73 m² increase: 0.94, 95% confidence interval 0.88-0.99). Receiver operator characteristics curves for the sensitivity and specificity of eGFR and mGFR for the prediction of CKD Stage ≥3 after LT found that pre-LT mGFR of 101 mL/min/1.73 m² and pre-LT eGFR of 124 mL/min/1.73 m² were the optimal thresholds for predicting Stage ≥3 CKD after LT.

Conclusion: The present study underlines the value of mGFR in the pre-LT stage and found major renal function loss after LT, and consequently two-thirds of patients have Stage ≥3 CKD at 1 year. All patients with a pre-LT mGFR <90 mL/min/1.73 m² warrant particular attention.

Keywords: chronic kidney disease; epidemiology; lung transplant; measured GFR.

FIGURE 1

Loss of mGFR and eGFR renal function after LT. (A) The mean ± SD loss of renal function post-LT was 48 ± 22 mL/min/1.73 m², corresponding to a relative loss of 55%. Pre-LT and post-LT mGFR values were significantly different. mGFR was measured using either inulin or iohexol clearance (see Concise Method section). (B) The mean ± SD loss of renal functionpost-LT was 58 ± 27 mL/min/1.73 m², corresponding to a relative loss of 52%. Pre-LT and post-LT eGFR values were significantly different. eGFR was estimated with CKD-EPI formula (see Concise Method section). *P < 0.05, paired t-test.

FIGURE 2

Bland–Altman plot of eGFR – mGFR in pre- and post-LT. (A) Mean bias was 18.7 ± 17.7 mL/min/1.73 m² for eGFR versus mGFR in pre-LT patients. (B) Mean bias was 5.0 ± 11.1 mL/min/1.73 m² for eGFR versus mGFR in post-LT patients. The solid line represents the mean difference and the dotted and dashed line the 95% limit of agreement. Pre-LT eGFR exhibited a significantly higher systematic bias and less accuracy compared with mGFR. Post-LT eGFR was as performant as mGFR.