Response to Nondipping in Patients With Hypertension
First, is siesta influencing the nocturnal BP dip? In the Spanish ambulatory blood pressure monitoring registry, the daytime period was calculated from the time of wake-up in the morning to the time of going to bed in the evening. However, in our opinion, 2 aspects minimize a possible impact of siesta in our results. First, the proportion of subjects who usually report to take a nap >3 times per week account for <8%, according to a recent survey of people representing the Spanish general population.3 Second, in this low proportion of subjects, the duration of siesta is <1 hour in most cases, thus representing <8% of the mean daytime blood pressure.4
Second, does nighttime administration of treatment induce nondipping? We are far away from suggesting this inverse association, in contrast with previous reports of controlled trials.5 In Table 1 of our main article,1 the proportion of patients taking all or a part of their medication at night was almost the same (20.5% among dippers and 21.2% among nondippers; P=0.352). In the online Table S1 of our article,1 nighttime systolic blood pressure dip was 8.2% in patients taking their medication only in the morning and 8.0% in those treated exclusively at night. In multivariate analyses (performed with either the nocturnal dip or with the proportion of nondippers), no statistical associations were observed at the time of drug administration. As we pointed out in our main article,1 the total number of drugs, which mainly reflects the severity of hypertension, was a potent factor influencing nocturnal dip.
Third, are there differences in the nocturnal dip depending on the type of the antihypertensive agent used? We have examined the information contained in our database of patients treated with monotherapy, including 5 major classes of antihypertensive drugs (a very low number were treated with α-blockers in monotherapy). Nocturnal dip was very similar among classes, with the exception of calcium channel blockers, which presented a slightly lesser nocturnal decline. However, these observations must be viewed with caution because of both the heterogeneity of pharmacokinetic and pharmacodynamic properties of different drugs belonging to the same class and the possible influence of other parameters, such as age and comorbidity.
Source of Funding
Main funding for the study was obtained from Lacer Spain, SA, through an unrestricted educational grant.
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