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

Chronic kidney disease after lung transplantation in a changing era

Lung transplant (LTx) physicians are responsible for highly complex post-LTx care, including monitoring of kidney function and responding to kidney function loss. Better survival of the LTx population and changing patient characteristics, including older age and increased comorbidity, result in growing numbers of LTx patients with chronic kidney disease (CKD). CKD after LTx is correlated with worse survival, decreased quality of life and high costs. Challenges lie in different aspects of post-LTx renal care. First, serum creatinine form the basis for estimating renal function, under the assumption that patients have stable muscle mass. Low or changes in muscle mass is frequent in the LTx population and may lead to misclassification of CKD. Second, standardizing post-LTx monitoring of kidney function and renal care might contribute to slow down CKD progression. Third, new treatment options for CKD risk factors, such as diabetes mellitus, proteinuria and heart failure, have entered clinical practice. These new treatments have not been studied in LTx yet but are of interest for future use. In this review we will address the difficult aspects of post-LTx renal care and evaluate new and promising future approaches to slow down CKD progression.

Calcineurin Inhibitor-Based Maintenance Immunosuppression in Lung Transplant Recipients: Optimal Serum Levels for Managing Acute Rejection and Renal Function

BACKGROUND

Although effective for curtailing alloimmune responses, calcineurin inhibitors (CNIs) have an adverse-effect profile that includes nephrotoxicity. In lung transplant (LTx) recipients, the optimal serum levels of the CNI tacrolimus necessary to control alloimmune responses and minimize nephrotoxicity are unknown.

METHODS

This retrospective, single-center study reviewed tacrolimus whole blood trough levels (BTLs), grades of acute cellular rejection (ACR), acute rejection scores, and creatinine clearance (CrCl) obtained in LTx recipients within the first year after their transplant procedure. Comparisons were made between the first 90 days post LTx (when tacrolimus BTLs were maintained >10 µg/L) and the remainder of the post-LTX year (when BTLs were <10 µg/L).

RESULTS

Despite tacrolimus mean BTLs being higher during the first 90 days post LTx compared with the remainder of the first post-LTx year (10.4 ± 0.3 µg/L vs 9.5 ± 0.3 µg/L, P < .0001) there was no association with lower grades of ACR (P = .24). The intensity of ACR (as determined by acute rejection scores) did not correlate with tacrolimus mean BTLs at any time during the first posttransplant year (P = .79). During the first 90 days post LTx there was a significant decline in CrCl and a correlation between increasing tacrolimus mean BTLs and declining CrCl (r = -0.26, P = .03); a correlation that was not observed during the remainder of the year (r = -0.09, P = .52).

CONCLUSIONS

In LTx recipients, maintaining BTLs of the CNI tacrolimus >10µg/L did not result in superior control of acute rejection responses but was associated with declining renal function.

Factors Related to Survival in Low-Glomerular Filtration Rate Cohorts Undergoing Lung Transplant

BACKGROUND

Historically, a glomerular filtration rate (GFR) of less than 50 mL/min per 1.73 m² has been considered a contraindication to lung transplantation. Combined or sequential lung-kidney transplantation is an option for those with a GFR less than 30 mL/min per 1.73 m². Patients with a GFR of 30 to 50 mL/min per 1.73 m² are provided with no options for transplantation. This study explores factors associated with improved survival in patients who undergo isolated lung transplantation with a GFR of 30 to 50 mL/min per 1.73 m².

METHODS

The United Network for Organ Sharing database was queried for adult patients undergoing primary isolated lung transplantation between January 2007 and March 2018. Regression models were used to identify factors associated with improved survival in lung recipients with a preoperative GFR of 30 to 50 mL/min per 1.73 m². The propensity score method was used to match highly performing patients (outpatient recipients aged less than 60 years) with a GFR of 30 to 50 mL/min per 1.73 m² with patients who had a GFR greater than 50 mL/min per 1.73 m². Kaplan-Meier, Cox, and logistic regression analyses compared outcomes in matched populations.

RESULTS

A total of 21,282 lung transplantations were performed during the study period. Compared with patients with a GFR greater than 50 mL/min per 1.73 m², survival was significantly worse for patients with a GFR of 30 to 50 mL/min per 1.73 m². Multivariate analysis of patients with a GFR of 30 to 50 mL/min per 1.73 m² demonstrated outpatient status and age less than 60 years to be predictive of superior survival. After propensity matching, survival of this highly performing subset with a GFR of 30 to 50 mL/min per 1.73 m² was no different from that of patients with a normal GFR.

CONCLUSIONS

Outpatient recipients aged less than 60 years represent an optimal subset of patients with a GFR of 30 to 50 mL/min per 1.73 m². Lung transplant listing should not be declined based only on a GFR less than 50 mL/min per 1.73 m².

Retransplantation Outcomes at a Large Lung Transplantation Program

Background

With the increase of primary lung transplantation across major centers worldwide, over the last several years the need of lung retransplant (ReTX) is likely to increase. Therefore, characterization of ReTX patients is prudent and necessary. Our study aimed to investigate and characterize the covariates and outcomes associated with lung ReTX survival in a single large U.S. transplant center.

Methods

Demographic, clinical diagnoses, and comorbidities were analyzed. Kaplan-Meier statistics were used to calculate and predict survival for 30 days and up to 3 years. Cox proportional modeling was used to determine the variables associated with mortality.

Results

Of included 684 lung transplants performed at the Houston Methodist Hospital between January 2009 and December 2015, 49 were lung ReTX. Median age of primary lung transplant (non-ReTX) and ReTx recipients was 62 and 49 years, respectively. Chronic graft rejection in the form of restrictive chronic lung allograft dysfunction and bronchiolitis obliterans syndrome was the main indications for ReTX. Compared with non-ReTX patients, ReTX patients had higher median lung allocation score (46.2 vs 37.0, respectively) and higher mortality after 6 months posttransplant. ReTX, older age, female sex, hospitalization 15 days or longer, estimated glomerular filtration rate less than 60, 6-minute walk distance less than 400 ft, and donor/recipient height ratio less than 1 were significantly associated with decreased 1-year patient and graft survival. Chronic graft rejection was still the major cause of death in the long-term follow-up recipients.

Conclusions

Our findings suggested that lung ReTX recipients have poor long-term survival outcomes. Lung ReTX should only be offered to carefully selected patients.