Optimal schedule of home blood-pressure measurements for the diagnosis of hypertension.

Various home blood-pressure (HBP) measurement schedules were compared to determine the optimal schedule of HBP measurement for the diagnosis of hypertension. Out of 319 individuals who were suspected of having hypertension based on office BP measurements and who did not take antihypertensive drugs, 157 individuals who completed 42 HBP measurements over 7 days and who had a valid 24-h ambulatory blood pressure (ABP) measurement were included in this analysis. We evaluated five HBP measurement schedules to determine the optimal HBP measurement schedule for the diagnosis of hypertension. The cumulatively averaged HBP from 5 to 6 measurement days showed a Pearson correlation coefficient of >0.990 compared to HBP averaged for 6 or 7 days depending on the method. The intraclass correlation coefficient of the cumulatively averaged HBP measurements compared with the 24-h ABP measurement was excellent (≥0.75) from the average of three measurement days and increased steadily with increasing averaged days of HBP measurements. Compared with a diagnosis using a 24-h ABP measurement, the diagnostic sensitivity, specificity, and positive and negative predictive values of HBP measurements were not different among the five methods. The diagnostic agreement of cumulatively averaged HBP measurements was nearly perfect (kappa ≥ 0.9) from the average of five measurement days compared with a diagnosis based on HBP measurements averaged for 6 or 7 days and diagnosis based on averaged HBP measurements of previous days. We suggest obtaining HBP measurements over 5 days or more, in the morning and evening, taking two or more measurements per occasion, and averaging all of the readings as the optimal schedule of HBP measurement for the diagnosis of hypertension.