Association of metabolic risk factors with uncontrolled hypertension: comparison of the several definitions of metabolic syndrome

Aims:To evaluate the influence of metabolic syndrome in the effectiveness of antihypertensive treatment and to compare it using the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) (2001 and 2004), International Diabetes Federation (IDF) and American Heart Association/National Heart, Lung and Blood Institute (AHA-NHLBI) definitions.Methods:The VALSIM (Estudo de Prevalencia da Sindrome Metabolica) survey was designed as an observational cross-sectional study performed in a primary healthcare setting in Portugal. The first two adult patients scheduled for an appointment on a given day were invited to participate. The treatment effectiveness was evaluated by the occurrence of uncontrolled hypertension (140/90mmHg) in patients taking antihypertensive drugs. Logistic regression analysis was used to determine the association between uncontrolled hypertension and metabolic risk factors, with adjustments for age, sex, and pattern of antihypertensive treatment.Results:Among the 16856 individuals evaluated, 8925-treated hypertensive patients were identified. Only 35.8% of them had controlled hypertension. The risk of poor blood pressure control increased with age, waist circumference, serum levels of triglycerides and HDL-cholesterol. Among treatable risk factors, metabolic syndrome as defined by NCEP-ATP III 2001 diagnostic criteria was the strongest independent predictor of uncontrolled hypertension (odds ratio: 1.23; 95% CI: 1.08-1.41; P=0.002). In opposition, the IDF or AHA-NHLBI definitions of metabolic syndrome failed to identify patients at risk of poor blood pressure control.Conclusion:Metabolic syndrome is associated with lower effectiveness of antihypertensive therapy and the NCEP-ATP III 2001 definition of metabolic syndrome is the one that better identifies patients at risk of poor blood pressure control.