Abstract
INTRODUCTION: Blood pressure (BP) exhibits a circadian rhythm characterized by higher levels during wakefulness and lower levels during sleep; however, the functional and structural impact of the rhythms of BP remains uncertain. METHODS: Two hundred hypertensive males aged 55 and older without overt cardiovascular or cerebrovascular diseases were enrolled in this longitudinal study. Of these, 188 were included in the analyses (12 lacked valid BP records for part of the 24-h period). Rhythmic profiling of BP was performed using ARSER, and rhythmicity was considered significant at p < 0.05. Estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology (CKD-EPI) formula. The primary outcome was the change in eGFR. RESULTS: The average age was 64.9 ± 7.2 years. For systolic BP (SBP), 38 of the subjects exhibited a 12-h rhythm and 43 subjects a 24-h rhythm; for diastolic BP (DBP), 38 exhibited a 12-h rhythm, and 36 exhibited a 24-h rhythm. During the 3-year follow-up period, 16 of the subjects died, and 36 were lost to follow-up. The mean eGFR at baseline and follow-up were, respectively, 86.6 ± 14.0 and 81.0 ± 17.1 mL min(-1) 1.73 m(-2) (p = 0.001). The urinary albumin:creatinine ratio did not vary significantly among the groups (p = 0.059). Subjects with 12-h rhythmic SBP exhibited a smaller reduction in eGFR than those with arrhythmic SBP (p = 0.014). However, the changes in eGFR were similar among the groups displaying 12-h or 24-h rhythmic DBP or arrhythmic DBP. We defined a decline in eGFR as a reduction of >1/2 SD between baseline and follow-up. Adjusting for confounding factors (including age, smoking, alcohol consumption, diabetes mellitus, BMI, albumin levels, administration time of antihypertensive drugs, and duration of hypertension), the risk of a decline in eGFR was 70% lower in subjects with 12-h rhythmic SBP than in those with arrhythmic SBP (heart rate = 0.307 [0.108-0.874], p = 0.027). CONCLUSION: SBP with a 12-h period is a protective predictor of the decline in eGFR in hypertensive males. It is, therefore, necessary to focus on the rhythmic profiling of BP.