Conventional, atypical, and combination antipsychotic prescriptions: a 2-year comparison.

BACKGROUND: The purpose of this study was to determine if there is a relationship between the type of antipsychotic prescribed (conventional, atypical, or a combination) and patients' use of psychiatric services and prescription of adjuvant medications.
METHOD: A chart review of 83 outpatients with long-term psychiatric disorders recorded the type and dosage of psychiatric medications prescribed in 1997-1998 (T1) and 2 years later, in 1999-2000 (T2). Psychiatric service use was also noted during the 2-year follow-up.
RESULTS: Atypical prescriptions increased from 27% (N = 22) to 45% (N = 37) 2 years later. At T2, 35% of patients (N = 29) were prescribed conventionals, and 19% (N = 16) were prescribed a combination of conventionals and atypicals. The mean antipsychotic dosage in chlorpromazine equivalents (546.5 mg/day) increased significantly (p <.05). There was no difference between the 3 groups in their use of psychiatric services or the prescription of adjuvant medications, with the exception of less common prescription of anticholinergics. There was also no difference in psychiatric service use between patients who remained on treatment with combined antipsychotics at T1 and T2 (11%; N = 9) and the rest of the sample. Patients who were switched from one type of antipsychotic to another made more use of psychiatric services, however.
CONCLUSION: Contrary to our expectations, patients prescribed combined antipsychotic types did not make more use of psychiatric services or use more adjuvant medications. The high percentage of patients prescribed a combination may be due to antipsychotic polypharmacy preferences and may represent a very slow crossover from one antipsychotic to another.