Efficacy of second-generation-antipsychotics in the treatment of negative symptoms of schizophrenia: a meta-analysis of randomized clinical trials.

OBJECTIVES To determine whether second-generation-antipsychotics (SGAs) are effective for negative symptoms treatment in schizophrenia. METHODS Two meta-analyses were carried out using placebo or haloperidol as comparators. The search included the following databases: Pubmed, The Cochrane Central Register of Controlled Trials, Proquest Health and Medical Complete, Science Citation Index Expanded, and Current Contents Connect. The outcome measure used was the change in negative symptoms, choosing a standardized statistic (Cohen's d) to synthesize the data. RESULTS In the placebo-controlled meta-analysis, the effect sizes (Cohen's d) obtained for amisulpride, haloperidol, olanzapine, quetiapine, risperidone and ziprasidone were 0.52, 0.34, 0.43, 0.36, 0.40 and 0.46, respectively, favoring active treatment against placebo (P<0.001 in all cases). The haloperidol-controlled meta-analysis only showed a statistically significant trend favoring antipsychotics over haloperidol (Cohen's d=0.15). CONCLUSIONS Most antipsychotics (amisulpride, haloperidol, olanzapine, quetiapine, risperidone and ziprasidone) are effective in the treatment of negative symptoms. Amisulpride and ziprasidone showed higher effect sizes.