Incident dementia in kidney transplantation recipients: a matched comparative nationwide cohort study in South Korea

Background: Recent studies have shown that patients with end-stage renal disease (ESRD) are at elevated risk of dementia. Howev-er, whether kidney transplantation (KT) lowers the risk for incident dementia remains unclear. Methods: From the Korean National Health Insurance Service database, we identified incident KT recipients aged >= 40 years without any history of dementia between 2007 and 2015. We also established a pair of age-, sex-, and inclusion year-matched control co-horts of patients with incident dialysis-dependent ESRD and members of the general population (GP) without a history of dementia, respectively. Cases of incident all-cause dementia, including Alzheimer disease (AD), vascular dementia (VD), and other kinds of de-mentia, were obtained from baseline until December 31, 2017. Results: We followed 8,841 KT recipients, dialysis-dependent ESRD patients, and GP individuals for 48,371, 28,649, and 49,149 pa-tient-years, respectively. Their mean age was 52.5 years, and 60.6% were male. Over the observation period, 55/43/19 KT recipi-ents, 230/188/75 dialysis-dependent ESRD patients, and 38/32/14 GP individuals developed all-cause dementia/AD/VD. The risks of incident all-cause dementia, AD, and VD in KT recipients were similar to those in GP (hazard ratio: 0.74 [p = 0.20], 0.74 [p = 0.24], and 0.59 [p = 0.18], respectively) and significantly lower than those in dialysis-dependent ESRD patients (hazard ratio: 0.17 [p < 0.001], 0.16 [p < 0.001], and 0.16 [p < 0.001], respectively). Older age and diabetes mellitus at the time of KT were risk factors for incident all-cause dementia and AD in KT recipients. Conclusion: This is the first study to show a beneficial impact of KT on incident dementia compared to dialysis dependency.