Longitudinal observations on circadian blood pressure variation in chronic kidney disease stages 3-5

Abstract

It has been suggested that status as a 'non-dipper' determined from 24-h blood pressure (BP) recordings is associated with increased risk of end-organ damage but little is known about the consistency of dipper status in renal patients. The present post hoc analysis evaluated dipper/non-dipper status prospectively in a study on dosage of enalapril in progressive chronic kidney disease (CKD) stages 3-5. In 34 patients, 24-h ambulatory BP (A&D TM2421) was measured at baseline and every 4 months for 1 year or until the need for renal replacement therapy. For each BP recording patients were classified as dippers or non-dippers based on the presence or absence of a nighttime reduction in both systolic and diastolic BP > 10%. Antihypertensive treatment aimed at an office BP < 120/80 mmHg. GFR was measured by the plasma clearance of (51)Cr-EDTA and albuminuria was determined from 24-h collections. A total of 125 24-h BP recordings were made. Ten patients were constant dippers and five were constant non-dippers throughout the study whereas nineteen patients changed dipping status apparently at random. When analysing pairs of sequential recordings in the individual patient, non-dipper and dipper status remained unaltered in 25 (27%) and 32 (35%) of comparisons, respectively, whereas it was inconsistent in 34 (38%) of cases. No correlation between dipper status and GFR, decline in renal function, degree of albuminuria or BP level could be demonstrated. The consistency of circadian BP variation seems to be poor in CKD stages 3-5 and single measurements of 24-h ambulatory BP are therefore probably inadequate for the evaluation of dipping status.