Blood pressure variability increases with advancing chronic kidney disease stage

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 16 546 patients [10 270 (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 13.8 ± 3.7 to 15.6 ± 5.4 mmHg), wSD (from 12.0 ± 3.2 to 13.9 ± 5.1 mmHg), CV (from 10.4 ± 2.7 to 11.5 ± 4.1%), ARV (from 9.9 ± 2.3 to 11.4 ± 3.2 mmHg); 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.