To determine the prevalence of metabolic syndrome (MS) in outpatients treated with antipsychotics included in a primary-health-care database.

A cross-sectional study was carried out assessing an administrative outpatients claim-database from 5 primary-health-centers. Subjects on antipsychotics for more than 3 months were included. The control group was formed by the outpatients included in the database without exposition to any antipsychotic drugs. MS was defined according to the modified NCEP-ATP III criteria, and required confirmation of at least 3 of the 5 following components: body mass index >28.8 kg/m2, triglycerides >150 mg/ml, HDL-cholesterol <40 mg/ml (men)/<50 mg/ml (women), blood pressure >130/85 mmHg, and fasting serum glucose >110 mg/dl.

We identified 742 patients [51.5% women, aged 55.1 (20.7) years] treated with first- or second-generation antipsychotics during 27.6 (20.3) months. Controls were 85.286 outpatients [50.5% women, aged 45.5 (17.7) years]. MS prevalence was significantly higher in subjects on antipsychotics: 27.0% (95% CI, 23.8–30.1%) vs. 14.4% (14.1–14.6%); age- and sex-adjusted OR = 1.38 (1.16–1.65, P < 0.001). All MS components, except high blood pressure, were significantly more prevalent in the antipsychotic group, particularly body mass index >28.8 kg/m2: 33.0% (29.6–36.4%) vs. 17.8% (17.6–18.1%), adjusted OR = 1.63 (1.39–1.92, P < 0.001), and low HDL-cholesterol levels: 48.4% (44.8–52.0%) vs. 29.3% (29.0–29.6%); adjusted OR = 1.65 (1.42–1.93, P < 0.001). Compared with the reference population, subjects with schizophrenia or bipolar disorder (BD), but not dementia, showed a higher prevalence of MS.

Compared with the general outpatient population, the prevalence of MS was significantly higher in patients with schizophrenia or BD treated with antipsychotics.