Antipsychotic treatment discontinuation in previously untreated patients with schizophrenia: 36-month results from the SOHO study.

Data from the 3-year, prospective, observational SOHO study were used to compare the effectiveness (in terms of treatment discontinuation) and the tolerability of olanzapine, risperidone, other atypicals and typical antipsychotics in 1009 previously untreated outpatients with schizophrenia who started monotherapy at baseline. Kaplan-Meier survival analysis estimated the time to treatment discontinuation by the treatment group, Cox proportional hazards regression models identified the variables associated with treatment discontinuation (adjusted for baseline differences between treatment groups), and logistic regression models compared the tolerability profiles of the different treatment groups. Of the 931 patients analyzed, 31.9% discontinued the medication initiated at baseline during the 3-year follow-up. Olanzapine had the lowest rate of discontinuation (28.9%), followed by other atypical (34.0%), risperidone (36.2%) and typical antipsychotics (44.5%). Compared to olanzapine, risk of treatment discontinuation was higher with typical antipsychotics (hazard ratio [HR] 1.75; 95% confidence interval [CI] 1.11, 2.78) or risperidone (HR 1.36; 95% CI 1.02, 1.82). A higher baseline Clinical Global Impression (CGI) positive score was associated with a higher risk of treatment discontinuation (HR 1.18; 95% CI 1.06, 1.30). Olanzapine was associated with a lower frequency of extrapyramidal symptoms than other antipsychotics, fewer prolactin-related adverse events than risperidone and other atypical antipsychotics, but greater weight gain than typicals and risperidone. For all analyses, comparison with the other atypical group is limited due to its small sample size (n=50). In conclusion, treatment effectiveness and tolerability varied among antipsychotic medications in previously untreated patients with schizophrenia. The results should be interpreted conservatively given the observational study design.