Tele-monitoring of home blood pressure in treated hypertensive patients

Aim: To compare the accuracy of clinic blood pressure (CBP) and telemedical home blood pressure (HBP) measurement in the assessment of antihypertensive effect. Methods: 362 patients on antihypertensive medication performed HBP measurement (5 days, duplicate measurements, four times daily) and ambulatory blood pressure (ABP) monitoring in random order. Main outcome measure was the agreement of CBP and HBP with daytime ABP. Results: CBP was much higher than ABP and average HBP (p < 0.001). There was a progressive decline in HBP over the course of the study, achieving the level of daytime ABP on the last 2 monitoring days. The correlation between CBP and ABP was weak (systolic: r = 0.343, diastolic r = 0.430), whereas strong correlations existed between HBP and ABP (systolic r = 0.804, diastolic r = 0.776). A progressive improvement in the strength of the correlation between average HBP of single days and ABP was obtained over the 5 monitoring days. The HBP readings taken in the afternoon showed a stronger correlation with ABP than the values measured in the morning, at noon and in the evening. Averaging more HBP readings taken on succeeding days resulted in a progressive improvement in the agreement with ABP with a further benefit when readings of day I were included. Conclusions: The accuracy of telemedical HBP measurement is substantially better than that of CBP. The results suggest, that HBP should be measured for 5 days, and afternoon measurements should be preferred in assessing control of hypertension.