AHRQ review finds few differences between first- and second-generation antipsychotics: In a new review of the comparative effectiveness of individual antipsychotics for treating adults with schizophrenia spectrum disorders or bipolar disorder, the Agency for Healthcare Research and Quality (AHRQ) found few differences of clinical importance in most outcomes, including functional outcomes and health care system use and health-related quality of life. Included in the review were 113 studies of schizophrenia and 11 studies of bipolar disorder. In terms of core illness symptoms, clozapine was more efficacious than chlorpromazine for patients with schizophrenia on the basis of the single reported scale. Results for haloperidol versus olanzapine were conflicting, with olanzapine favored on one scale but no differences on two other scales. Haloperidol was favored over quetiapine on the basis of four scales. No differences were found for haloperidol versus aripiprazole, clozapine, risperidone, and ziprasidone. The most frequently reported adverse events with significant differences were extrapyramidal symptoms; in most cases, the second-generation agent had fewer extrapyramidal symptoms than haloperidol. The review found that outcomes such as death and quality of life were rarely assessed and that data comparing side effects were sparse. Inconsistencies across studies made drawing firm conclusions difficult. The review is available on the AHRQ Web site at www.effectivehealthcare.ahrq.gov.