Prognostic role of ambulatory blood pressure measurement in patients with nondialysis chronic kidney disease

Background: Ambulatory blood pressure (BP) measurement allows a better risk stratification in essential hypertension compared with office blood pressure measurement, but its prognostic role in nondialysis chronic kidney disease has been poorly investigated. Methods: The prognostic role of daytime and nighttime systolic BP (SBP) and diastolic BP (DBP) in comparison with office measurements was evaluated in 436 consecutive patients with chronic kidney disease. Primary end points were time to renal death (end-stage renal disease or death) and time to fatal and nonfatal cardiovascular events. Quintiles of BP were used to classify patients. Results: The mean (SD) age of the patients was 65.1 (13.6) years, and the glomerular filtration rate was 42.9 (19.7) mL/min/1.73 m ²; 41.7% of the participants were women, 36.5% had diabetes, and 30.5% had cardiovascular disease. Office-measured SBP/DBP values were 146 (19)/82(12) mm Hg; daytime SBP/DBP was 131 (17)/75 (11) mm Hg, and nighttime SBP/DBP was 122(20)/66 (10) mm Hg. During follow-up (median, 4.2 years), 155 and 103 patients reached the renal and cardiovascular end points, respectively. Compared with a daytime SBP of 126 to 135mmHg, patients with an SBP of 136 to 146mmHg and those with an SBP higher than 146 mm Hg had an increased adjusted risk of the cardiovascular end point (hazard ratio [HR], 2.23; 95% confidence interval [CI], 1.13-4.41 and 3.07; 1.54-6.09) and renal death (1.72; 1.02-2.89 and 1.85; 1.11-3.08). Nighttime SBPs of 125 to 137 mm Hg and higher than 137 mm Hg also increased the risk of the cardiovascular end point (HR, 2.52; 95% CI, 1.11-5.71 and 4.00; 1.77-9.02) and renal end point (1.87; 1.03-3.43 and 2.54; 1.41-4.57) with respect to the reference SBP value of 106-114 mm Hg. Office measurement of BP did not predict the risk of the renal or cardiovascular end point. Patients who were nondippers and those who were reverse dippers had a greater risk of both end points. Conclusion: In chronic kidney disease, ambulatory BP measurement and, in particular, nighttime BP measurement, allows more accurate prediction of renal and cardiovascular risk; office measurement of BP does not predict any outcome.