Ambulatory or home blood pressure monitoring for treatment adjustment?

T he study by Niiranen et al 1 in this issue of the Journal addressed an important clinical issue. The research question was whether equally effective hypertension control can be achieved by treatment adjustment on the basis of daytime ambulatory blood pressure (dABP) or home blood pressure (HBP) measurement. The main conclusion of the authors that there were no significant between-group differences (dABP versus HBP group) is correct. However, because of low study power, several clinically important differences probably did not reach statistical significance (eg, regarding HBP decline, control rates, triple therapy). For example the 14.2% between-group difference in control rates was nonsignificant but is clinically important. In fact the 95% confidence intervals include a difference in control rates as high as 34%. Another conclusion of the authors that requires special attention is the nonsignificant trend to a larger proportion of patients reaching the target pressure in the HBP group. This statement is correct because in the HBP group the HBP goal was reached in 57.7% of subjects, whereas in the dABP group the dABP goal was reached in 43.5% of subjects. On the other hand it is wrong because if both measurement methods are considered, there is a consistent trend for more effective control in the dABP group, with HBP and dABP targets reached in 60.9% and 43.5% respectively, compared with 57.7% and 38.5% respectively in the HBP group. This puzzling finding is probably attributed to the fact that at randomization dABP was higher than HBP by 4/3.5 mm Hg (systolic/diastolic). Despite this difference the target blood pressure (BP) was the same for dABP and HBP (diastolic BP 80 mm Hg). Thus in the dABP group dABP had to be reduced by 14.4 mm Hg, whereas in the HBP group HBP had to be reduced by 10.5 mm Hg. One might have predicted that subjects in the dABP group would receive more intensive treatment (triple therapy was