• Mean change from baseline to Week 13 for total score using the Structured Clinical Interview- Positive and Negative Syndrome Scale (SCI-PANSS)
  

• Change from baseline through each visit and at study end (Week 53) for SCI-PANSS total score, SCI-PANSS subscales, Clinical Global Impression (CGI) and Wisconsin Quality of Life Index (W-QOLI). Safety evaluations throughout the study.
  

Many schizophrenia patients currently take oral antipsychotic medications daily, but long-acting injectable formulations may eliminate this need for the daily medication. This is an open-label study of a flexible does of a long-acting formulation of risperidone injected into the muscle at 2 week intervals over 12 months in patients with schizophrenia or schizoaffective disorder. A comparator group will receive daily tablets of olanzapine, a psychotropic agent available for the treatment of schizophrenia and schizoaffective disorders. This is a two-part trial. Patients will be titrated to the most effective dose of trial medication during the first 13 weeks and analyzed for short-term efficacy and safety of treatment at Week 13. Patients will be then assessed for maintenance of efficacy, safety, and resource use at Week 52 (second part of study). Efficacy assessments include the Structured Clinical Interview - Positive and Negative Syndrome Scale (SCI-PANSS), overall severity of illness measured by the Clinical Global Impression (CGI) scale, and quality of life assessed by Wisconsin Quality of Life Index (W-QOLI). Safety evaluations include incidence of adverse events, Simpson and Angus Rating Scale for extrapyramidal symptoms, physical examinations, clinical laboratory tests (biochemistry, haematology, and urinalysis), and electrocardiograms (ECGs). The primary study hypothesis is that treatment with long-acting risperidone injected intramuscularly every 2 weeks is not inferior to treatment with daily olanzapine in terms of short-term efficacy and is well tolerated by patients with schizophrenia or schizoaffective disorder.

Risperidone injections (25mg or 50mg) every 2 weeks for 12 months. Investigator may decrease or increase dosages (max 50mg) or supplement risperidone injections with risperidone tablets (4mg/day max.). Control group receives olanzapine tablets (5mg) daily, adjusted as necessary (max 20mg).