Clinical correlates of antipsychotic polytherapy in patients with schizophrenia in Singapore.

The purpose of the present study wa to determine the prevalence of antipsychotic polytherapy (use of more than one antipsychotic drug at one time) and its clinical correlates among 300 hospitalized psychotic Asian patients diagnosed with schizophrenia. It was hypothesized that such treatment would be associated with more severe illness than in comparable monotherapy patients, and with higher chlorpromazine-equivalent (CPZ) total daily doses. Clinical and demographic details were obtained from the medical records and direct clinical examinations. Polytherapy was encountered in 215 of the 300 patients (71.7%), with an average number of 1.8 antipsychotics (range 1-4) prescribed at a mean CPZ daily dose of 612 +/- 528 mg (median: 464 mg, range: 25-2500 mg). The 215 patients prescribed more than one antipsychotic agents were younger, ill longer, more likely to be taking at least one high-potency agent, in receipt of higher average daily CPZ doses, and more likely to be prescribed anticholinergic agents but with similar admission illness severity rating (Brief Psychiatric Rating Scale) scores compared to the 85 patients given only one antipsychotic drug at one time. The high rate of antipsychotic polytherapy that appeared to be unrelated to current illness severity suggests that this practice may not consistently be based on rational therapeutic principles.