Background:
Although the validity and safety of antipsychotic polypharmacy remains unclear, it is commonplace in the treatment of schizophrenia. This study aimed to investigate the degree that antipsychotic polypharmacy contributed to metabolic syndrome in outpatients with schizophrenia, after adjustment for the effects of lifestyle.
Methods:
A cross-sectional survey was carried out between April 2007 and October 2007 at Yamanashi Prefectural KITA hospital in Japan. Participants included 599 patients who met the criteria for an ICD-10 diagnosis of schizophrenia, schizotypal and delusional disorders, receiving outpatient treatment, and aged 18 years or older. Of 599 patients, 334 patients (55.8%) consented to this cross-sectional study. We measured the components constituting metabolic syndrome, and interviewed the participants about their lifestyle (dietary habits, physical activity, and smoking habits). We classified metabolic syndrome into three groups according to the severity of metabolic disturbance: the metabolic syndrome; the pre-metabolic syndrome; and the visceral fat obesity (included both the pre-metabolic and metabolic syndrome groups). We used logistic regression models to assess the association of metabolic syndrome with antipsychotic polypharmacy, adjusting for lifestyle.
Results:
Seventy-four (22.2%) patients were in the metabolic syndrome group, 135 (40.4%) patients were in the pre-metabolic syndrome group, and 176 (52.7%) patients were in visceral fat obesity group. Antipsychotic polypharmacy was present in 167 (50.0%) patients. In logistic regression analyses, antipsychotic polypharmacy was significantly associated with the pre-metabolic syndrome group (adjusted odds ratio [AOR], 1.77; 95% confidence interval [CI], 1.02-3.06) and the visceral fat obesity group (AOR, 1.78; 95%CI, 1.02-3.10), but not with the metabolic syndrome group (AOR, 0.96; 95%CI, 0.51-1.80).
Conclusions:
These results suggest that antipsychotic polypharmacy is partially associated with metabolic syndrome even after adjustment for the effect of patients’ lifestyle. Despite antipsychotic polypharmacy not being recommended in the treatment of schizophrenia, it has been common practice in the past. As metabolic syndrome is associated with an increased risk of cardiovascular mortality, further studies are needed to clarify the validity and safety of antipsychotic polypharmacy.