title: Increased risk of extrapyramidal side-effect treatment associated with atypical antipsychotic polytherapy.
abstract: OBJECTIVE
  To determine whether atypical antipsychotic polytherapy is a risk factor for drug treatment for extrapyramidal side-effects (anti-EPS drugs) and whether the risk is attributable to antipsychotic dose.
  
  
  METHODS
  We studied Iowa Medicaid beneficiaries aged 18-64 years with an active atypical and no conventional antipsychotic on January 1, 2001. The association of atypical antipsychotic polytherapy with anti-EPS drug treatment was determined. Multiple logistic regression was utilized to adjust for covariates in two models, the first adjusting for age, sex and the specific antipsychotic(s) prescribed, and the second also adjusting for doses.
  
  
  RESULTS
  Among 4400 patients, the unadjusted odds of anti-EPS treatment were increased two-fold with polytherapy. Polytherapy remained a risk factor in the first model (OR 1.5, 95% CI 1.1-2.0), but not after adjusting for doses (OR 1.0, 95% CI 0.7-1.4).
  
  
  CONCLUSIONS
  Atypical antipsychotic polytherapy is a risk factor for anti-EPS drug treatment, apparently because of higher cumulative doses.
authors.affiliation: Department of Pharmacy: Clinical and Administrative Sciences, The University of Oklahoma College of Pharmacy, Tulsa, OK 74135, USA. ryan-carnahan@ouhsc.edu
authors.forename: R M
authors.initials: RM
authors.lastname: Carnahan
authors.forename: B C
authors.initials: BC
authors.lastname: Lund
authors.forename: P J
authors.initials: PJ
authors.lastname: Perry
authors.forename: E A
authors.initials: EA
authors.lastname: Chrischilles
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001480:Basal Ganglia Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology; D001569:Benzodiazepines / Q000008:administration & dosage / Q000009:adverse effects; D003024:Clozapine / Q000008:administration & dosage / Q000009:adverse effects; D003430:Cross-Sectional Studies; D003692:Delayed-Action Preparations; D003987:Dibenzothiazepines / Q000008:administration & dosage / Q000009:adverse effects; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007484:Iowa; D008297:Male; D008432:Mathematical Computing; D008484:Medicaid; D008875:Middle Aged; D015233:Models, Statistical; D000077152:Olanzapine; D011358:Product Surveillance, Postmarketing; D011618:Psychotic Disorders / Q000188:drug therapy* / Q000453:epidemiology; D000069348:Quetiapine Fumarate; D012044:Regression Analysis; D012307:Risk Factors; D018967:Risperidone / Q000008:administration & dosage / Q000009:adverse effects; D013223:Statistics as Topic
chemical_list: D014150:Antipsychotic Agents; D003692:Delayed-Action Preparations; D003987:Dibenzothiazepines; D001569:Benzodiazepines; D000069348:Quetiapine Fumarate; D003024:Clozapine; D018967:Risperidone; D000077152:Olanzapine