To the Editor:
Mitsutake and colleauges1 conducted a cross-sectional clinical study and concluded that hypertension is significantly associated with coronary artery disease (CAD) as assessed by coronary computed tomography (CT). They first recognized that age and the metabolic syndrome are both significantly associated with CAD, and then several metabolic components such as hypertension, dyslipidemia, diabetes, and visceral fat were used as independent variables to analyze the relationship with CAD. Although there is a report that visceral fat, one of the main metabolic components, has a significant association with CAD evaluated by multidetector CT,2 Mitsutake and associates could not find an association between visceral fat and CAD. There is a limitation in this cross-sectional study to validate a cause-effect relationship. On this point, risk assessment by follow-up study on the incidence of cerebrovascular/cardiovascular disease showed that there was no significant contribution of waist circumference on the incidence of cerebrovascular/cardiovascular disease, especially in men.3
As an example, the author describes the results of a 3-year prospective follow-up study in the workplace. A total of 2648 men with no history of cerebrovascular/cardiovascular disease were recruited. The rate of incidence on cerebrovascular/cardiovascular disease was 28. As the sample number was limited, the author did not differentiate cerebrovascular and cardiovascular disease. The risk assessment of metabolic components and age on the incidence of cerebrovascular/cardiovascular disease was conducted by logistic regression analysis, and odds ratios (ORs) with 95% confidence intervals (CIs) was calculated with SPSS 16.0J statistical package for Windows (SPSS Japan Inc, Tokyo, Japan). The author judged metabolic components binary according to the criteria of the National Cholesterol Education Program.4
The ORs for age and high blood pressure for cerebrovascular/cardiovascular disease were 1.10 (CI, 1.04–1.17; P<.01) and 3.07 (CI, 1.21–7.83; P<.05), respectively. In contrast, there was no significant contribution of increased waist circumference, increased fasting glucose, increased triglyceride, and decreased high-density-lipoprotein cholesterol (OR, 0.75 [CI, 0.34–1.66]; OR, 0.92 [CI, 0.41–2.08]; OR, 0.90 [CI, 0.36–2.24]; and OR, 0.92 [CI, 0.19–4.42], respectively.
Using data from a 3-year follow-up study in the workplace, increased blood pressure in men significantly contributed to the incidence of cerebrovascular/cardiovascular disease in concordance with reports by Mitsutake and associates.1 In addition, there was no significant contribution of waist circumference on the incidence of cerebrovascular/cardiovascular disease as Mitsutake and coworkers1 and Furukawa and colleagues3 separately pointed out.
There was a limitation in the number of events with a relatively younger population. In addition, the period of follow-up was relatively short. To improve validation of this study, continuous follow-up of this population is needed.