Response to HYVET ambulatory blood pressure substudy

Bursztyn et al speculate that our ambulatory blood pressure (ABP) participants were not representative of the whole trial. We agree this is possible but very unlikely in view of the similarity of the participant characteristics given in Table 1. As the elderly frequently nap, he wonders if this would substantially reduce daytime pressure. However, we also looked at morning ABP to confirm our findings, and this would not be affected by a postlunch sleep. The online-only Data Supplement gives some details on the much smaller number (52) of participants who had ABP before and after the initiation of treatment. Bursztyn et al select the 17 participants who had white coat hypertension and active treatment and note that their ABP did not change. They conclude that active treatment does not lower ABP in those with white coat hypertension. This is not true as the placebo-active pressure difference was 21/10 mm Hg when the groups were compared. The rise with placebo and no change with active treatment are almost certainly because of regression to the mean, and an identical result was observed in the Systolic Hypertension in Europe (Syst-Eur) trial.