Home ambulatory blood pressure readings do not differ from clinic readings taken at the same time of day.

In most hypertensives clinic blood pressure (BP) is variably higher than home BP, but the underlying mechanisms are uncertain. We investigated whether the 24-hour ambulatory home BP profile as well as the office-home BP discrepancy could vary with the time of day of application of the recording system (from 08.00 h to 19.00 h) in 135 untreated hypertensives who underwent non-invasive home BP monitoring (ICR 5200). Neither systolic nor diastolic 24-hour home BP (average of daily readings, area-under-the-curve) varied significantly with the time of day of application of the system. Clinic BP was about 12% higher than 24-hour home BP in the whole population, mean values being 161.4/102.9 mmHg (office BP) vs 141.2/90.8 mmHg (average 24-hour home readings), as well as in each of the subcohorts based on the time of day of application of the system (all P less than 0.01). However, in none of the subcohorts were there any statistically significant differences between clinic BP and home BP readings taken at the same time of day as the clinic readings. No correlation was found between clinic heart rate and clinic-home discrepancy. We conclude that in essential hypertension 24-hr non-invasive ambulatory BP monitoring can begin indifferently from 08.00 h to 19.00 h with no expected influence of time of application on results and that clinic BP is not dissimilar from home BP at the same time of day.