Efficacy of antipsychotic treatment in schizophrenia: results after 24 months in Italian patients in the Schizophrenia Outpatient Health Outcomes (SOHO) study

Methods SOHO is a prospective, observational study of the treatment of schizophrenia in over 10,000 patients in 10 European countries; 3,016 patients were enrolled in Italy. Data were collected at 6-month intervals. Given the complexity of the data, which include medication changes during follow-up, novel statistical methods have been applied, which include epoch analysis. In epoch analysis, patients are considered to have a new treatment episode when they change medication. Patients who switched antipsychotic treatment at 6, 12 or 18 months had their new treatment considered as a new baseline observation. Patients were then classified as having continuous antipsychotic treatment for 6, 12, 18 or 24 months. The following treatment groups were analysed: olanzapine, risperidone, quetiapine, clozapine, oral typicals and depot typicals. Multivariate analysis, adjusting for baseline covariates, examined treatment effects on various outcomes measures: clinical symptom severity (Clinical Global Impression-Schizophrenia Scale, CGI-overall), quality of life (EuroQol-5 dimensions visual analogue scale, EQ-VAS), social functioning (social activities, paid employment) and tolerability (incidence of extra-pyramidal symptoms [EPS] and weight change). Each treatment group was compared with the olanzapine group.