The SOHO (Schizophrenia Outpatient Health Outcome) study: Implications for the treatment of schizophrenia

The European SOHO (Schizophrenia Outpatient Health Outcome) study is an observational, naturalistic study of the outpatient treatment of schizophrenia. The patient recruitment and assessment began in September 2000 and finished in early 2005. A total of 10 972 adult patients from ten European countries who were initiating or changing antipsychotic medication for the treatment of schizophrenia within the normal course of care have been enrolled. The patients have been followed at regular intervals over the 3-year timeframe of the study. Evaluation includes clinical severity, measured with the Clinical Global Impression (CGI) scale; health-related quality of life; social functioning; and medication tolerability. The 6- and 12-month results have been published so far and have demonstrated that the patients in whom treatment was initiated with olanzapine or clozapine or who were started on more than one antipsychotic of any class at baseline tended to have somewhat greater improvement than patients treated with other atypical or typical antipsychotics, both in terms of symptoms measured with the CGI and quality of life. Numbers of social contacts increased with the treatment, but other aspects of social functioning did not show any significant change. Atypical antipsychotics as a class were associated with a lower frequency of extrapyramidal symptoms (EPS) and anticholinergic use than typical antipsychotics. The frequency of EPS was lowest in the clozapine-, quetiapine- and olanzapine-treated patients, at around 10%. The atypical antipsychotics also conferred a lower risk for tardive dyskinesia than the typical antipsychotics. Weight gain occurred in all treatment cohorts over the first 12 months of treatment and was statistically significantly greater in the patients who started treatment with olanzapine and clozapine. Prolactin- and sexually-related adverse events were frequent at baseline assessment: amenorrhoea was present in around onethird of women, impotence in around 40% of men, and loss of libido in 50% of both male and female patients. Patients treated with olanzapine, clozapine and quetiapine were significantly less likely to have sexual/endocrine-related dysfunctions after 6 months of treatment (the 12-month results of this parameter are yet to be published) than those in the other treatment cohorts (typical antipsychotics, risperidone and amisulpride). Concomitant medication use during the study has been high, ranging from 5% to 29% for anticholinergics, 8% to 23% for antidepressants, 22% to 37% for anxiolytics and 7% to 19% for mood stabilisers, depending on the type of antipsychotic prescribed. Fewer olanzapine-, quetiapine- and clozapine-treated patients used concomitant anticholinergics or anxiolytics/ hypnotics. The current results from the SOHO study indicate that differences in effectiveness and tolerability do exist between the antipsychotics. Future results from the study will be published during the coming months and years, and will allow patterns of antipsychotic use in routine clinical practice (including how often and why changes are made) to be determined. This important information is likely to impact on the future use of antipsychotics and will assist clinicians in refining the use of these drugs and improving the outcome of patients to whom they are prescribed.