Masked Hypertension in Treated Hypertensive Patients

To the Editor We read with interest the Critique article by Clement1 regarding our article2 and we are grateful for his comments. However, some aspects need to be clarified to avoid confusion. Clement1 states that the population we studied may be different from that seen in regular hypertension clinics, and that we come up with a very high prevalence of masked hypertension (340 of 742 patients). For reference, Clement reports the prevalence of masked hypertension in the office versus ambulatory study,3 that is, 143 of 1963 patients. We studied 466 patients with apparently responder hypertension (340 with responder hypertension and 126 with masked hypertension), and 276 patients with apparently resistant hypertension (ie, receiving ≥3 drugs; 146 with false resistant hypertension and 130 with true resistant hypertension).2 These subjects were selected from a larger treated hypertensive population (1715 patients) who underwent clinic blood pressure (BP) recording and ambulatory BP monitoring (because these 742 patients met the inclusion criteria for this study, ie, apparently responder and apparently resistant hypertension). The other patients receiving one or two drugs with uncontrolled clinic BP were not included in this study. These data are reported in the article, but probably we did not emphasize them.2 Thus, the prevalence of masked hypertension in our study2 is 126 of 466 apparently responder subjects, and 126 of all 1715 treated subjects submitted to clinic BP recording and ambulatory BP monitoring, and not 340 of 742 patients. The prevalence of 126 of 1715 in our study2 does not seem to be different from the prevalence of 143 of 1963 in the study by Clement et al.3 In the original report by Clement et al,3 by using a cutoff of 135 mm Hg for 24-h systolic BP, the prevalence of masked hypertension was 71 of 447 apparently responder subjects (group with clinic systolic BP <140 mm Hg) and 71 of all 1963 treated patients. The data reported in the Critique article1 probably result from a reclassification of subjects according to a cutoff for daytime BP to compare the studies. Bobrie et al,4 by using home BP, specifically evaluated for the first time the prevalence and prognostic relevance of masked hypertension in elderly treated subjects. In their study the prevalence of masked hypertension was 462 of 1147 apparently responder subjects, and 462 of all 4939 treated subjects.4 Recently, other studies have been published about this topic. In the study by Stergiou et al,5 the prevalence of masked hypertension was 29 of 72 apparently responder subjects, and 29 of all 150 treated subjects. In the study by Ohkubo et al,6 the prevalence of masked hypertension was 74 of 232 apparently responder subjects, and 74 of all 405 treated subjects. In another report, Obara et al,7 by using home BP, reported a prevalence of masked hypertension of 782 of 1428 apparently responder subjects, and a prevalence of 782 of all 3400 treated subjects. Table 1 summarizes the prevalence of masked hypertension in treated hypertensive patients evaluated in those studies. The prevalence of masked hypertension in our study,2 both among apparently responder subjects and all treated subjects, is within the range of the literature data. Prevalence of masked hypertension in treated hypertensive patients Apparently responder hypertension is defined as clinic BP <140/90 mm Hg. This study used a cutoff of 135 mm Hg for 24-h systolic BP These data probably result from a reclassification of subjects according to a cutoff for daytime BP These studies used home BP with a cutoff of 135/85 mm Hg These studies used a cutoff of 135/85 mm Hg for daytime BP. The sequence of the article is in accordance with their appearance in the literature. Prevalence of masked hypertension in treated hypertensive patients Apparently responder hypertension is defined as clinic BP <140/90 mm Hg. This study used a cutoff of 135 mm Hg for 24-h systolic BP These data probably result from a reclassification of subjects according to a cutoff for daytime BP These studies used home BP with a cutoff of 135/85 mm Hg These studies used a cutoff of 135/85 mm Hg for daytime BP. The sequence of the article is in accordance with their appearance in the literature. It can be concluded that, according to available data, the exact prevalence of masked hypertension in treated hypertensive patients is not yet clear, depending on patient characteristics and population studied. In any case, this topic deserves attention and efforts should be made to identify possible predictors of masked hypertension and submit these patients to ambulatory BP monitoring to avoid underestimation of cardiovascular risk in a portion of treated hypertensive patients.