Blood pressure categories, hypertensive subtypes, and the metabolic syndrome

Background Elevated blood pressure (BP) is one element of metabolic syndrome (MetS); however, the relation of various BP categories and hypertension subtypes to the likelihood of having MetS is not well defined. Methods We determined the odds of MetS, defined by the National Cholesterol Education Program, in various BP categories from a cross-sectional study of 5968 individuals aged at least 18 years and untreated for hypertension (weighted to 124.7 million) in the National Health and Nutrition Examination Survey, 1999-2002. Nonhypertensive BP categories were optimal, normal, and high-normal BP, according to JNC-VI classification. Hypertension consisted of three subtypes: isolated diastolic hypertension (IDH), systolic-diastolic hypertension (SDH), and isolated systolic hypertension (ISH). Results Among those with hypertension and MetS, 25.3% had IDH, 20.2% had SDH, and 54.5% had ISH. The MetS prevalence in nontreated persons was 5.8% for optimal BP, 9.1% for normal BP, 38.2% for high-normal BP, 45.9% for IDH, 44.3% for SDH, and 43.9% for ISH. Risk factor odds ratios (95% confidence intervals; reference group, optimal BP), adjusted for age, sex, total cholesterol, and smoking, were 1.6 (1.2-2.2) for normal BP, 9.4 (6.9-12.7) for high-normal BP, 14.7 (8.9-24.0) for IDH, 12.2 (7.2-20.8) for SDH, and 10.2 (7.0-14.9) for ISH (all P < 0.01); odds ratios were higher for women in all categories. Conclusions Despite having the lowest mean age, IDH subtype is associated with greatest likelihood of MetS. The high frequency of ISH in the hypertensive population, however, makes ISH the most common hypertensive subtype in persons with MetS.