Introduction: The metabolic syndrome (MS) is a constellation of risk factors of metabolic origin that is associated with increased risk of type 2 diabetes mellitus (DM) and cardiovascular disease (CVD). Several regional studies have been conducted to determine its prevalence, but they are insufficient to determine the situation nationally or to characterize overall cardiovascular risk in Portugal.
Objective: To determine the prevalence of MS and each of its components in adult primary health care users in Portugal.
Methods: The VALSIM Study, involving 719 general practitioners (GPs), was performed in a primary care setting, based on stratified distribution and proportional to the population density of each region of mainland Portugal and the islands of Madeira and the Azores. The first two adult patients scheduled for an appointment on a given day were invited to participate, irrespective of the reason for the consultation. After informed consent was obtained, a questionnaire on sociodemographic, clinical and laboratory data was completed by the GP. A previous diagnosis of coronary artery disease (CAD), stroke or DM was identified by the GP based on medical records. A diagnosis of MS was defined according to the NCEP ATP III criteria. Logistic regression multivariate analysis was used to assess the risk of MS according to age, body mass index (BMI), waist circumference (WC) and region of residence for each gender, and to determine the association of CAD, stroke and DM with gender, age, BMI, WC, blood pressure and previous diagnosis of hypertension (HT), fasting glucose and previous diagnosis of DM.
Results: The study included 16,856 individuals (mean age 58.1+/-15.1 years, 18-96 years; 61.62% women). The prevalence of MS adjusted for gender, age and size of region was 27.5% and showed regional variations, being highest in the Alentejo (30.99%) and lowest in the Algarve (24.42%). MS was more common among women and increased with age, BMI and WC. Independent protective factors were residence in the Algarve (odds ratio [OR]: 0.78; 95% confidence interval [CI] 0.66-0.92 p=0.002) or in Lisbon and Tagus Valley (OR: 0.83, 95% CI 0.77-0.91, p<0.001), while residence in the Northern (OR: 1.11; 95% CI 1.01-1.21, p=0.03) or Central regions (OR: 1.08; 95% CI 1.002-1.16, p=0.045) was an independent risk factor after correction for gender and age. MS was linked to increased prevalence of HT (OR: 3.88; 95% CI 3.61-4.18, p<0.001), and high blood pressure was the most frequent MS component, particularly in men (93.7%). MS was the most powerful factor associated with a diagnosis of DM, particularly in women (OR 7.23; 95% CI 6.22-8.40, p<0.001). Although there was a strong association between MS and CAD (OR: 1.16; 95% CI 1.01-1.34, p=0.043), the most potent risk factor associated with CVD was HT.
Conclusions: The prevalence of MS in Portugal is high (27.5%) and is strongly linked to the occurrence of CVD, and in particular to DM. These results highlight the need to implement preventive strategies for reducing overall cardiovascular risk in the Portuguese population.