Author + information
- Stanley S. Franklin, MD∗ (, )
- Lutgarde Thijs, MSc and
- Jan A. Staessen, MD, PhD
- ↵∗Heart Disease Prevention Program, Division of Cardiology, School of Medicine, University of California, Irvine, 1001 Health Sciences Road, Irvine, California 92697-4079
The meta-analysis by Dr. Huang and colleagues (1) critiquing our study (2) failed to note the importance of using age-matching rather than age-adjusting in persons with white-coat hypertension (WCH) versus their normotensive comparators. Indeed, we noted in the JACC study that the white-coat effect increased dramatically with age, so that there was about a 3.9 mm Hg increase in the white-coat effect per decade of age from about 30 to 80 years of age (see Figure 1). Because there was a 12-year greater age in the patients with WCH than in their normotensive comparators in the JACC WCH study, this alone would falsely increase cardiovascular disease (CVD) risk considerably in this IDACO (International Database of Ambulatory blood pressure in relation to Cardiovascular Outcome) study of persons with WCH (2). The Huang and colleagues' (1) meta-analysis was based on age-adjusted summary statistics, an approach that is less effective than age matching in removing the confounding effect of age.
Secondly, Huang and colleagues (1) concluded from their aggregate data meta-analysis that WCH is associated with increased cardiovascular risk both in participants aged <55 years and in those ≥55 years. Our subject-level meta-analysis is obviously the preferred method to assess the differential effect of age on the risk associated with WCH. Indeed, the Huang and colleagues' (1) statement on subjects <55 years was based on 5 studies with an average age <55 years. Their results are probably partly driven by the inclusion of subjects age ≥55 years with multiple cardiovascular risk factors.
Thirdly, Huang and colleagues (1) suggested that the IDACO JACC study was underpowered to detect risk in individuals age <60 years. This IDACO study consisted of 653 subjects with WCH from 11 countries and with a 10.6-year follow-up for new cardiovascular events. This consisted of 494 persons with WCH <60 years of age (75.7% consisted of younger subjects) and 159 persons with WCH age ≥60 years (24.3% consisted of older subjects). To our knowledge, this is the largest group of subjects with untreated WCH in the published reports and with the longest follow-up for new cardiovascular events.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation