Neurocognitive deficits may not resolve following pediatric kidney transplantation

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.