Comparing the Effectiveness of Aripiprazole and Quetiapine in Schizophrenia and Related Psychoses: A Naturalistic, Retrospective Chart Review Study

Background: Naturalistic studies offer advantages over randomized clinical trials by including patients seen in routine practice. Aripiprazole and quetiapine are the most recent second-generation antipsychotics available in the United Kingdom. We aimed to study all patients who were prescribed these medications in a defined geographic area in order to identify and compare those who had a good clinical response.

Method: We conducted an electronic chart review of a sample of all people attending secondary mental health care in the county of Lanarkshire, Scotland, who were treated with aripiprazole or quetiapine for schizophrenia and related psychoses (ICD-10 criteria) between 2002 and 2007. To measure effectiveness, we retrospectively assigned Clinical Global Impressions (CGI) scores and examined medication discontinuation rates.

Results: Eighty-nine patients were started on treatment with aripiprazole and 132 patients with quetiapine over the 5-year period. Those treated with quetiapine had a higher initial illness severity (CGI – Severity of Illness scale) (p = .0003), were more likely to be starting rather than switching antipsychotics (p=.0003), were more likely to have a mood disorder (p = .03), were less likely to be treatment resistant (p = .005), and had lower rates of prescription of additional antipsychotics (p = .009). After adjusting for these variables, the proportions who improved according to CGI were 74% with aripiprazole and 67% with quetiapine. Overall medication discontinuation rates were also similar, 42% for aripiprazole and 45% for quetiapine, with early discontinuation of aripiprazole being noticeable, often due to agitation (13% of all patients treated with the drug).

Conclusion: Despite their different pharmacologic properties, aripiprazole and quetiapine were similarly effective in the majority of patients. Early discontinuation of aripiprazole due to agitation was an important finding.