Association between visit-to-visit blood pressure variability and risks of dementia in CKD patients: a nationwide observational cohort study

Background The association between visit-to-visit blood pressure (BP) variability and dementia risk in chronic kidney disease (CKD) patients has rarely been studied. Methods In this retrospective observational study, individuals who received three or more general health screenings were identified in the nationwide database of Korea. Those with persistent non-dialysis-dependent CKD [estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or dipstick albuminuria ≥1+] were included. The study exposure was systolic or diastolic BP variability, calculated as the variation independent of the mean and categorized into quartiles (Q4: the highest quartile; Q1: the lowest quartile). The risks of all-cause dementia, including Alzheimer's disease and vascular dementia, were analyzed by Cox regression adjusted for various clinical characteristics, including baseline BP and eGFR values. Results We included 103 139 CKD patients and identified 7574 (7%) dementia events, including 5911 (6%) Alzheimer's disease cases, 886 (1%) vascular dementia events and 777 (1%) cases categorized as other types of dementia. Higher systolic BP variability was significantly associated with higher risks of all-cause dementia {[Q4 versus Q1], hazard ratio [HR] 1.173 [95% confidence interval (CI) 1.102–1.249], P for trend < .001}. The results were also significant for the risk of Alzheimer's disease [HR 1.162 (95% CI 1.083–1.248), P < .001] and vascular dementia [HR 1.282 (95% CI 1.064–1.545), P = .039]. The results were similar when diastolic BP variability was the exposure, as high diastolic BP variability was significantly associated with higher risks of all-cause dementia [HR 1.191 (95% CI 1.117,1.270), P < .001]. Conclusions Higher visit-to-visit BP variability is significantly associated with a higher risk of dementia in CKD patients.