Short-acting parenteral antipsychotics drive choice for classical versus atypical agents

The objective of this study was to investigate which antipsychotics (classical versus atypical) are prescribed in a psychiatric hospital and which determinants affect the choice for one of these two classes of antipsychotics in newly admitted patients.

In a retrospective cohort design, 522 newly admitted patients were followed from the date of admission until discharge from the hospital. In the cohort of newly admitted patients treated with an oral antipsychotic, a nested case-control study was conducted considering recipients of an atypical agent as cases. Controls were all other cohort members. The association of patient characteristics and the choice between classical versus atypical antipsychotics was studied using logistic regression analysis. The same analysis was performed with adjustment for possible confounding factors (age group, gender, DSM-IV diagnoses, use of short-acting parenteral antipsychotic, global assessment of functioning score, involuntary admissions and involuntary measures).

Patients treated with classical oral antipsychotics were more often previously treated with short-acting parenteral antipsychotics than patients treated with atypical antipsychotics (40.8% vs 15.2%; adjusted OR=0.20 95% CI=0.09-0.44). No statistically significant difference was found between patients with different severities of disease.

Availability of injectable forms seems to drive the choice for oral antipsychotic agents. Future introductions of short-acting parenteral atypical antipsychotics may have a large impact on first-choice oral antipsychotic treatment.