Does antipsychotic polypharmacy increase the risk for metabolic syndrome?

Objective: To determine whether the coprescribing of two or more antipsychotics, a relatively frequent practice with little data to support its safety and efficacy, is associated with an increased prevalence of metabolic syndrome. Methods: 364 newly admitted adults treated with second-generation antipsychotics underwent assessments evaluating antipsychotic polytherapy, and of the presence of metabolic syndrome and triglycerides/high-density lipoprotein cholesterol ratio > 3.5 (TG/HDL), a sensitive marker of insulin resistance. The correlates of antipsychotic polytherapy and associations with metabolic syndrome and TG/HDL were determined by univariate comparisons and multiple logistic regression analyses. Results: Antipsychotic polytherapy was present in 70 patients (19.2%) and was significantly more likely in patients with schizophrenia and those treated with clozapine, quetiapine or ziprasidone (p < 0.0001). Compared with antipsychotic monotherapy, polytherapy was associated with elevated rates of metabolic syndrome (50.0% vs. 34.3%, p=0.015) and TG/HDL (50.7% vs. 35.0%, p=0.016). However, in logistic regression analyses, metabolic syndrome was significantly associated with higher body mass index (BMI), older age, a diagnosis of bipolar disorder or schizophrenia, and cotreatment with a first-generation antipsychotic (r(2): 0.25, p < 0.0001). The TG/HDL marker of insulin resistance was associated with higher BMI, male sex, Caucasian race and absence of aripiprazole treatment (r(2) : 0.14, p < 0.0001). Antipsychotic polypharmacy dropped out of both multivariate models. Conclusions: Compared with patients receiving antipsychotic monotherapy, patients on antipsychotic polytherapy have higher rates of metabolic syndrome and lipid markers of insulin resistance. However, antipsychotic polytherapy is not independently associated with the prevalence of these abnormalities, which are related to known demographic, clinical and anthropometric risk factors. Published by Elsevier B.V.