Long-term renal outcomes in patients with traumatic brain injury: A nationwide population-based cohort study

Background: Traumatic brain injury (TBI) is an important cause of death and disability worldwide. The relationship between TBI and kidney diseases is largely unknown. Methods: We aimed to determine whether TBI is associated with long-term adverse renal outcomes. We performed a nationwide, population-based, propensity score-matched cohort study of 32,152 TBI patients and 128,608 propensity score-matched controls. Data were collected by the National Health Insurance Research Database of Taiwan from 2000 to 2012. Our clinical outcomes were chronic kidney disease (CKD), end-stage renal disease (ESRD) and the composite endpoint of ESRD or all-cause mortality. Results: The incidence rate of CKD was higher in the TBI than in the control cohort (8.99 vs. 7.4 per 1000 person-years). The TBI patients also showed higher risks of CKD (adjusted hazard ratio [aHR] 1.14, 95% confidence interval [CI] 1.08-1.20; P < 0.001) and composite endpoints (aHR 1.08, 95% CI 1.01-1.15; P = 0.022) than the control groups, but the ESRD was not significantly different between the groups. In subgroup analyses, the risks of incident CKD and composite endpoints were significantly raised in TBI patients aged < 65 years and/or without comorbidities. However, the risks of both CKD and composite outcome were little affected by the severity of TBI. Conclusions: TBI has a modest but significant effect on incident CKD and composite endpoint, but not on ESRD alone. TBI patients under 65 are at greater risk of CKD and composite outcome than their older counterparts.