Abstract Body: Background
Visit-to-visit blood pressure variability is strongly associated with adverse kidney and cardiovascular outcomes in a wide range of patient populations. Patients with chronic kidney disease (CKD) have abnormal circadian blood pressure patterns which may affect 24-hour ambulatory blood pressure variability (ABPV).
Methods
We used ambulatory blood pressure monitoring (ABPM) data from participants in the Chronic Renal Insufficiency Cohort (CRIC). Blood pressures were obtained every 30 minutes during day and night. We assessed 24-hour, daytime and nighttime systolic ABPV using average real time variability (ARV); the sum of the absolute differences between consecutive BP readings divided by the total number of readings minus one. Cox proportional hazards models were used to evaluate the association of ARV with the development of 50% reduction in eGFR or end stage kidney disease or adverse cardiovascular (CV) events (myocardial infarction, stroke, peripheral artery disease, new atrial fibrillation, and heart failure).
Results
There were 1502 CRIC participants included in the analysis of whom 44% were female and mean age was 63 years (standard deviation 10). Anthropometric and clinical factors associated with higher tertile of ARV included older age, higher BMI, higher urine protein to creatinine ratio, lower estimated glomerular filtration rate, diabetes, hypertension, dyslipidemia and atherosclerotic heart disease. In unadjusted Cox proportional hazard models, 24-hour systolic ARV was associated with both adverse kidney (Hazard Ratio [HR] 1.16 95% confidence interval [CI] 1.06-1.27) and CV events (HR 1.35 95%CI 1.22-1.50). However, in adjusted models that included clinical and sociodemographic factors, there were no statistically significant associations of 24-hour systolic ARV with either adverse kidney (HR 1.02, 95%CI 0.91-1.14) or CV events (HR 0.93, 95%CI 0.84 -1.04). Similarly, daytime and nighttime ARV were not statistically significantly associated with kidney and CV events in adjusted analyses.
Conclusions
In a large cohort of patients with CKD, ABPV was not associated with adverse kidney and CV outcomes in adjusted models. Thus, in the context of the many cardiometabolic risk factors present in patients with CKD, ABPV is not an independent mechanism of adverse clinical outcomes in this high-risk population.