UBC Theses and Dissertations
Antipsychotic prescribing patterns on admission to and discharge from a tertiary care program for treatment-resistant psychosis at Riverview Hospital Lee, Lik Hang
The treatment of psychosis typically requires the use of only one antipsychotic. Even in instances of treatment-resistant psychosis, the atypical antipsychotic clozapine has proven to be effective when used on its own. However, antipsychotic polypharmacy is commonly prescribed despite a lack of evidence for this practice. This concurrent use of two or more antipsychotics can also prolong the time before clozapine is tried. Antipsychotic polypharmacy should be reserved for instances of clozapine-resistant psychosis if it is to be used at all. In this retrospective study, data were collected from individuals who were referred to a tertiary care program for treatment-resistant psychosis. The main objectives were to compare the use of antipsychotic monotherapy to polypharmacy in treatment-resistant psychosis and to characterize within-individual changes in treatment and symptomatology secondary to hospitalization. At admission, individuals who were prescribed only one antipsychotic were comparable to those who were prescribed at least two antipsychotics with regard to demographics and symptom severity. The use of drugs other than antipsychotics was also similar between groups. However, the magnitude of antipsychotic utilization was greater in individuals who were receiving antipsychotic polypharmacy. In addition, a greater proportion of these individuals received excessive doses at admission. Similar findings were observed when monotherapy and polypharmacy were compared at discharge. Three important patterns were identified when investigating within-individual changes. First, fewer individuals were on polypharmacy at discharge. This was accompanied by a general decrease in both the number of antipsychotics prescribed and the magnitude of antipsychotic utilization. Second, the number of individuals who were prescribed clozapine had increased by discharge. Those who were already prescribed clozapine at admission typically had their doses increased. Third, improvements in symptomatology were observed across all of the subscales included in the Positive and Negative Syndrome Scale (PANSS). However, only 57.9% of individuals experienced a relative reduction in PANSS scores greater than 20%. Based on these findings, it is possible to alleviate the symptoms of psychosis in treatment-resistant psychosis while reducing antipsychotic utilization. Although this may seem counterintuitive, an increase in the use of clozapine and a decrease in antipsychotic polypharmacy may have contributed to clinical improvement.