Neurocognitive deficits may not resolve following pediatric kidney transplantation

Abstract

Background: Pediatric chronic kidney disease (CKD) patients are at risk for cognitive deficits with worsening disease progression. Limited, existing cross-sectional studies suggest that cognitive deficits may improve following kidney transplantation. We sought to assess cognitive performance in relationship to kidney transplantation and kidney-specific medical variables in a sample of pediatric kidney transplant patients who provided cross-sectional and longitudinal observations.

Methods: A retrospective chart review was conducted in patients who completed pre- and/or post-transplant neurocognitive testing at the University of Iowa from 2015-2021. Cognitive outcomes were investigated with developmentally appropriate, standardized measures. Mixed linear models estimated the impact of transplant status on cognitive function (z-scores). Subsequent post-hoc t-tests on change scores were limited to patients who had provided pre- and post-transplant assessments.

Results: Thirty eight patients underwent cognitive assessments: 10 had both pre- and post-transplant cognitive assessments, 11 had pre-transplant assessments only, and 17 had post-transplant data only. Post-transplant status was associated with significantly lower full-scale IQ and slower processing speed compared to pre-transplant status (estimate = -0.32, 95% confidence interval [CI] = -0.52: -0.12; estimate = -0.86, CI = -1.17: -0.55, respectively). Post-hoc analyses confirmed results from the mixed models (FSIQ change score = -0.34, 95% CI = -0.56: -0.12; processing speed change score = -0.98, CI = -1.28: -0.68). Finally, being ≥80 months old at transplant was associated with substantially lower FSIQ compared to being <80 months (estimate = -1.25, 95% CI = -1.94: -0.56).

Conclusions: Our results highlight the importance of monitoring cognitive function following pediatric kidney transplant and identify older transplant age as a risk factor for cognitive deficits.

Figure 1

CONSORT diagram of sample.

Figure 2

Impact of transplant status on neurocognitive outcomes. Panel A shows the estimates for transplant status derived from multivariable, mixed linear models. Panel B scores the change score from 8 individuals with repeated assessments. The vertical line marks 0, i.e., no significant association. The number of observations per assessment domain are noted.

Figure 3

Impact of age at transplant (<80 months vs. ≥80 months) on neurocognitive outcomes. The estimates (z-scores) were mixed linear models that were adjusted for random effects of participants. The vertical line marks 0, i.e., no significant association. The number of individual test observations for each domain are noted.