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Multicenter Study
. 2019;49(2):103-110.
doi: 10.1159/000496061. Epub 2019 Jan 9.

Comorbidity, Frailty, and Waitlist Mortality among Kidney Transplant Candidates of All Ages

María Pérez Fernández  1 , Patricia Martínez Miguel  1 , Hao Ying  2 , Christine E Haugen  2 , Nadia M Chu  3 , Diego María Rodríguez Puyol  1 , Leocadio Rodríguez-Mañas  4 , Silas P Norman  5 , Jeremy D Walston  6 , Dorry L Segev  2   3 , Mara A McAdams-DeMarco  7   8
Affiliations
Multicenter Study

Comorbidity, Frailty, and Waitlist Mortality among Kidney Transplant Candidates of All Ages

María Pérez Fernández et al. Am J Nephrol. 2019.

Abstract

Background: Kidney transplantation (KT) candidates often present with multiple comorbidities. These patients also have a substantial burden of frailty, which is also associated with increased mortality. However, it is unknown if frailty is merely a surrogate for comorbidity, itself an independent domain of risk, or if frailty and comorbidity have differential effects. Better understanding the interplay between these 2 constructs will improve clinical decision making in KT candidates.

Objective: To test whether comorbidity is equally associated with waitlist mortality among frail and nonfrail KT candidates and to test whether measuring both comorbidity burden and frailty improves mortality risk prediction.

Methods: We studied 2,086 candidates on the KT waitlist (November 2009 - October 2017) in a multicenter cohort study, in whom frailty and comorbidity were measured at evaluation. We quantified the association between Charlson comorbidity index (CCI) adapted for end-stage renal disease and waitlist mortality using an adjusted Cox proportional hazards model and tested whether this association differed between frail and nonfrail candidates.

Results: At evaluation, 18.1% of KT candidates were frail and 51% had a high comorbidity burden (CCI score ≥2). Candidates with a high comorbidity burden were at 1.38-fold (95% CI 1.01-1.89) increased risk of waitlist mortality. However, this association differed by frailty status (p for interaction = 0.01): among nonfrail candidates, a high comorbidity burden was associated with a 1.66-fold (95% CI 1.17-2.35) increased mortality risk; among frail candidates, here was no statistically significant association (HR 0.75, 95% CI 0.44-1.29). Adding this interaction between comorbidity and frailty to a mortality risk estimation model significantly improved prediction, increasing the c-statistic from 0.640 to 0.656 (p < 0.001).

Conclusions: Nonfrail candidates with a high comorbidity burden at KT evaluation have an increased risk of waitlist mortality. Importantly, comorbidity is less of a concern in already high-risk patients who are frail.

Keywords: Comorbidity; Frailty; Kidney transplantation.

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Conflict of interest statement

CONFLICT OF INTEREST STATEMENT

None. The results presented in this paper have not been published previously in whole or part, except in abstract format.

Figures

Figure 1:
Figure 1:
Overlap of Frailty, Disability, and Comorbidity among Kidney Transplant (KT) Candidates of All Ages. The Charlson comorbidity index (CCI) is modified for ESRD patients and we defined a high comorbidity burden as a CCI score of ≥2 and low comorbidity burden as a CCI score of 0 or 1.
Figure 2:
Figure 2:
Risk of Waitlist Mortality by Charlson Comorbidity Index (CCI) Among Kidney Transplant (KT) Candidates of All Ages. We defined a high comorbidity burden as a CCI score of ≥2 and low comorbidity burden as a CCI score of 0 or 1.
See this image and copyright information in PMC

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