Patients with schizophrenia at risk for excessive antipsychotic dosing

Patient Outcomes Research Team treatment recommendations were used to investigate the relationship between patient characteristics and higher-than-recommended dosages (> 1000 chlorpromazine equivalents [CPZe]) at discharge.

Inpatients who met the DSM-IV criteria for schizophrenia or schizoaffective disorder were recruited from 4 general hospitals. For those patients (N = 293) prescribed antipsychotics at discharge, chi-square tests and multiple regression analyses were used to assess the relationship between demographics, admission characteristics, comorbid diagnoses, and antipsychotic dosages. The relationship between clinical symptoms and antipsychotic dosage at discharge was also examined.

Antipsychotic dosages conformed to treatment guidelines for approximately 65% of patients; 21% received doses in excess of recommended levels. African American patients and those with a history of psychiatric hospitalization were more likely to be prescribed discharge antipsychotic doses greater than 1000 CPZe. Hospital differences in antipsychotic management were also observed. Regression analyses indicated that higher-than-recommended dosages found among African American patients could not be explained by differences in symptom levels at discharge. Patients with more thought disorder were also more likely to be prescribed antipsychotic dosages in excess of the recommended range. Compared with oral administration, depot administration increased the risk of excess dosage by a factor of 30. Controlling for method of administration reduced the impact of race to nonsignificance.

These results replicate earlier findings that minority individuals are more likely to be prescribed dosages in excess of the recommended range and suggest that this pattern is due to higher use of depot injection in African American patients. Further research should examine how patient characteristics and institutional factors influence medication use.