Blood pressure variability increases with advancing chronic kidney disease stage: a cross-sectional analysis of 16546 hypertensive patients

Objective:Increased BP-variability predicts cardiovascular morbidity and mortality in hypertensives. This study aimed to examine short-term BP-variability according to renal function stage.Methods:We included 16546 patients [10270 (62.1%) without/6276 (38.9%) with CKD Stage 1-5] from the Spanish Ambulatory-Blood-Pressure Monitoring (ABPM) Registry. Stages of CKD were defined according to K/DIGO criteria, based on estimated glomerular filtration rate calculated with the CKD-EPI equation and albumin-to-creatine ratio. BP-variability was assessed with standard deviation (SD), weighted SD (wSD), coefficient of variation (CV), and average real variability (ARV).Results:Compared with those without CKD, a lower proportion of CKD patients were dippers (51.9 versus 39.6%; P<0.001). Across CKD stages, a progressive decrease in dipper (from 39.1 to 20.4%; P<0.001) and increase in riser proportion (from 12.3 to 36.7%; P<0.001) were noted. Patients with CKD had significantly higher SBP SD, wSD, CV and ARV and lower DBP SD compared with those without CKD (P<0.001). Within CKD Stages, an increasing trend from Stage 1 towards Stage 5 was observed for SBP SD (from 13.83.7 to 15.6 +/- 5.4mmHg), wSD (from 12.0 +/- 3.2 to 13.9 +/- 5.1mmHg), CV (from 10.4 +/- 2.7 to 11.5 +/- 4.1%), ARV (from 9.9 +/- 2.3 to 11.4 +/- 3.2mmHg); P<0.001 for all comparisons. DBP SD (P<0.001), wSD and ARV (P=0.002) were slightly decreasing, whereas DBP CV increased from Stage 1 to Stage 4 (P<0.001). In multivariate analysis, male gender, older age, abdominal obesity, diabetes, number of antihypertensive medications, and clinic SBP were independent factors for higher SBP 24-h ARV in CKD.Conclusion:An increase in short-term SBP-variability was present with advancing CKD stages in a large cohort. This increased SBP-variability may be involved in the sharp elevation of cardiovascular risk with worsening renal function.