Prevalence and Diagnosis of Chronic Kidney Disease in Maintenance Lung Transplant Patients: ICEBERG Study

Background: Chronic renal dysfunction (CRD) after lung transplantation (LT) is a common and noteworthy complication associated with increased morbidity and mortality rates. The study objectives were to determine the prevalence of CRD according to different diagnostic criteria and describe its therapeutic management.

Methods: This observational, multicenter, retrospective study included LT patients with ≥ 2 years of evolution. CRD was defined according to 2 different methods: (1) by the physician's subjective clinical criteria and (2) by analytical criteria (estimated glomerular filtration rate [eGFR] by Modification of Diet in Renal Disease of ≤ 59 mL/min).

Results: We included 113 patients; 65.5% were men and the mean age at transplant was 49.1 (12.6) years. At 6 months after transplant, approximately half of patients had CRD according to analytical criteria, and, at 2 years after transplantation, the prevalence rose to 80%. Although clinical prevalence and analytical prevalence were similar (68.8% and 78.6%), a weak concordance was observed (Kappa index: 0.6). Among patients who were not classified as having CRD according to clinical criteria, 40.0% (14/35) were diagnosed with CRD according to analytical criteria. None of the patients underwent renal biopsy, and 5.1% of patients required dialysis. In 77.0% of patients with clinical CRD diagnosis, the immunosuppressive regimen was modified: reduction of isolated calcineurin inhibitors (CNIs) (35.0%), CNIs decreased with mycophenolic acid change (23.3%), and CNIs lowering with mammalian target of rapamycin introduction (6.7%). In a multivariate logistic regression model, the independent factors associated with CRD were an older recipient age, low body mass index (BMI) at transplant, treatment with cyclosporine/azathioprine, and low eGFR at the first month after transplant.

Conclusions: We found a high incidence of CRD at the first year after transplantation, which increased subsequently. Moreover, CRD was considerably underestimated by physicians' subjective clinical criteria. End points related to CRD development were older age, low BMI, azathioprine use, and low eGFR during the first month after transplant. The latter finding provides an opportunity to implement prevention strategies.