Purpose: We examined the characteristics of the day-by-day variability of home blood pressure (HBP) in patients with chronic kidney disease (CKD).
Methods: We obtained HBP recordings from 368 CKD patients (63+/-13 years, eGFR 34+/-23 mL/min/1.73 m2, males 253). The day-by-day variability of HBP was defined as the coefficient of variation (CV) values of BP measurements every morning after waking and every evening before sleeping on 7 consecutive days. In a portion of the patients, the CV values of HBP were collected every 6 months during a 2-year period and the association with a decline in GFR was examined.
Results: CV values of morning/evening systolic BP (SBP) were 5.4+/-2.4%, 6.1+/-2.9 % (p<0.01). The CV values of morning SBP in females or patients with diabetic nephropathy (DN) were significantly greater than those in males or patients without DN, respectively (females 5.9+/-2.3%, males 5.2+/-2.4%, p< 0.01, DN 6.1+/-2.8 %, non DN 5.2+/-2.2 %, p<0.05). Multivariate linear regression analysis showed that female gender, DN, the number of antihypertensive drugs, higher heart rate and higher CV values of heart rate were associated with higher CV values of the morning SBP. CV values of the morning SBP showed no significant change during the 2-year period (0; 5.4+/-2.6%, 1 year; 5.3+/-2.9%, 2 years 5.6+/-3.1%, n=200). There was no significant difference in the change in eGFR between a group with high CV values (greater than 5 %) and a group with low CV values (lower than 5 %) during the 2-year period.
Conclusions: In CKD patients, the day-by-day variability of HBP tended to be greater in the evening, in female and DN patients. There was no significant association between the day-by-day variability of HBP and decline rate in eGFR. Further studies are needed to clarify the clinical significance of the day-by-day variability of HBP in CKD patients.