Relapse Rates in Patients With Schizophrenia Receiving Aripiprazole in Comparison With Other Atypical Antipsychotics

Objective: Aripiprazole is the first of a new generation of antipsychotics that possesses a unique mechanism of action as a partial dopamine agonist. After the release of aripiprazole, case reports appeared conveying an acute psychosis/agitation reaction occurring after the initiation of treatment, most specifically after patients were switched from a previous antipsychotic to aripiprazole. The primary objective of this study was to compare relapse rates among patients with schizophrenia who were switched to aripiprazole with those who switched to a second-generation antipsychotic (SGA) from another antipsychotic.

Method: The design was a retrospective cohort study based on Kansas Medicaid enrollees with an ICD-9-CM diagnosis code for schizophrenia during calendar year 2002 who switched antipsychotic agents. Six-month psychiatric relapse rates, defined as hospitalization for a psychiatric event, were compared between those subjects who switched to aripiprazole and those who switched to another SGA. Time to relapse was modeled using Cox proportional hazards, adjusting for demographic characteristics, major comorbid conditions, and prior psychiatric-related health care use.

Results: Four hundred forty-four aripiprazole and 521 SGA switchers were comparable with respect to gender, race, comorbidities, and health care utilization, though the aripiprazole group was 4.5 years younger. Twenty percent of aripiprazole patients and 19.4% of patients receiving SGAs were hospitalized 6 months after being switched (relative risk = 0.92; 95% CI = 0.67 to 1.26). Mean times to psychiatric hospitalization for the aripiprazole and SGA groups were 65.7 and 73.8 days, respectively (p > .05). Factors associated with hospitalization were prior psychiatric hospitalizations and comorbid depression, substance abuse, and neurotic, personality, and nonpsychotic mental disorders.

Conclusion: Our study found that rates of relapse and time to relapse with aripiprazole were comparable to other SGAs during a 6-month period. Thus, aripiprazole appears to be an appropriate first-line agent along with the other SGAs.