Blood Pressure Variability, Mortality, and Cardiovascular Outcomes in CKD Patients

Abstract

Background and objectives: Short-term BP variability (derived from 24-hour ambulatory BP monitoring) and long-term BP variability (from clinic visit to clinic visit) are directly related to risk for cardiovascular events, but these relationships have been scarcely investigated in patients with CKD, and their prognostic value in this population is unknown.

Design, setting, participants, & measurements: In a cohort of 402 patients with CKD, we assessed associations of short- and long-term systolic BP variability with a composite end point of death or cardiovascular event. Variability was defined as the standard deviation of observed BP measurements. We further tested the prognostic value of these parameters for risk discrimination and reclassification.

Results: Mean ± SD short-term systolic BP variability was 12.6±3.3 mm Hg, and mean ± SD long-term systolic BP variability was 12.7±5.1 mm Hg. For short-term BP variability, 125 participants experienced the composite end point over a median follow-up of 4.8 years (interquartile range, 2.3-8.6 years). For long-term BP variability, 110 participants experienced the composite end point over a median follow-up of 3.2 years (interquartile range, 1.0-7.5 years). In adjusted analyses, long-term BP variability was significantly associated with the composite end point (hazard ratio, 1.24; 95% confidence interval, 1.01 to 1.51 per 5-mm Hg higher SD of office systolic BP), but short-term systolic BP variability was not (hazard ratio, 0.92; 95% confidence interval, 0.68 to 1.25 per 5-mm Hg higher SD of 24-hour ambulatory systolic BP). Neither estimate of BP variability improved risk discrimination or reclassification compared with a simple risk prediction model.

Conclusions: In patients with CKD, long-term but not short-term systolic BP variability is related to the risk of death and cardiovascular events. However, BP variability has a limited role for prediction in CKD.

Keywords: Ambulatory Care; Prognosis; Renal Insufficiency, Chronic; Systole; blood pressure; cardiovascular; chronic kidney disease; hypertension; mortality risk.