OMEGA study: design, baseline data, metabolic syndrome prevalence in a large-scale observational study of hypertensive patients: The Olmesartan Mega Study to Determine the Relationship between Cardiovascular Endpoints and Blood Pressure Goal Achievement study.

Elevated systolic blood pressure increases the risk of cardiovascular events, as shown by a number of meta-analyses of large-scale clinical trials. As concerns the prognostic impact of the metabolic syndrome on cardiovascular events, few large-scale studies are available in the Japanese hypertensive population. The prospective, large-scale, observational OMEGA (Olmesartan Mega Study to Determine the Relationship between Cardiovascular Endpoints and Blood Pressure Goal Achievement) study sought to examine the relationship between the incidence of cardiovascular disease (CVD) and achieved blood pressure, metabolic syndrome, lifestyle factors and other risk factors for CVD in patients with hypertension. Of the 15,313 enrolled patients from 2,219 institutions in Japan, we report here the baseline characteristics of the 14,841 eligible patients whose baseline data were collected as of October 31, 2007. Men and women 50 to 79 years old (mean age 65) with physician-diagnosed hypertension were enrolled, and all patients were treated with open-label olmesartan medoxomil (5 to 40 mg daily). The majority of patients (75%) had mild to moderate hypertension. The prevalences of dyslipidemia and diabetes mellitus were 48% and 24%, respectively. The metabolic syndrome was identified in 48% and 19% of the evaluable men and women, respectively, using the criteria of the Japanese Society of Internal Medicine. Men with the metabolic syndrome were at the greatest risk for CVD, and a greater proportion of men than of women had all five metabolic syndrome components. The complete follow-up data from the OMEGA study will provide much-needed information to guide treatment in patients with hypertension and the metabolic syndrome. (Hypertens Res 2008; 31: 2011-2017).