Patient, provider and payer characteristics associated with antipsychotic drug polypharmacy in ambulatory care

Objectives. Antipsychotic drug polypharmacy, the practice of using more than one antipsychotic drug to manage psychotic disorders is an increasing practice although studies are needed to understand factors that contribute to this practice particularly in ambulatory care settings. The purpose of this study were to evaluate current prescribing trends in antipsychotic drug polypharmacy, assess patient demographic factors related to antipsychotic drug polypharmacy and to determine provider characteristics that are associated with antipsychotic drug polypharmacy in office based settings.;Methods. The study combined 2002, 2003 and 2004 data from the National Ambulatory Medical Care Survey (NAMCS) to investigate the proportion of patients that were prescribed multiple antipsychotics compared to single antipsychotics. A logistic regression analysis and a chi-square test were used to examine the correlation between patient characteristics as well as provider variables and prescribing of multiple antipsychotic drugs.;Results. Antipsychotic monotherapy were prescribed for 91.8% (N=762) of the patients meeting the criteria of the study compared to 8.2% (N=68) prescribed antipsychotic polypharmacy making a total sample size of 830 patients. The patient's age, gender and physician specialty had no significant role in the physicians' decision to prescribe single or multiple antipsychotics in the same patient. Based on a chi-square test, patients classified as non-White were more likely to receive multiple antipsychotic drugs compared to White individuals. Patients whose method of payment were reported as Medicare were up to twice as likely to receive multiple antipsychotic drugs compared to those with private insurance Wald(1)=3.99, p=.046, Exp(B)=2.59. Likewise, the Medicaid payment status increased antipsychotic polypharmacy rate by three times, Wald(1)=8.13, p=004, Exp (B)= 3.49.;Conclusions. The influence of age and patient payment status on antipsychotic prescribing patterns need further investigation. More studies are necessary to determine why some patients are predisposed to antipsychotic polypharmacy.