OBJECTIVE The Seroquel Patient Evaluation on Changing Treatment Relative to Usual Medication (SPECTRUM) study assessed the efficacy and tolerability of quetiapine (Seroquel™) in patients with schizophrenia switched from treatments providing suboptimal outcomes. METHODS This was an international, open-label, non-comparative study, designed with titration to 400 mg/day quetiapine over 7 days, then flexible dosing (300-750 mg/day) for 11 weeks. Efficacy was assessed with the Positive and Negative Syndrome Scale (PANSS); Clinical Global Impression (CGI) Severity of Illness and Global Improvement scores; and the Calgary Depression Scale for Schizophrenia (CDSS). Clinical benefit and tolerability were also assessed. RESULTS The mean modal dose of quetiapine was 505 mg/day; 509 patients switched to quetiapine from olanzapine (13%), risperidone (11%), conventional antipsychotics (37%) and combinations of antipsychotics (28%), amongst others. Significant decreases in CGI Severity of Illness and PANSS scores and a significant improvement in CDSS score resulted from the switch (all P<0.001 versus baseline). There were significant reductions in extrapyramidal symptoms (EPS) on the Simpson-Angus Scale (SAS) and Barnes Akathisia Scale (BAS) (both P<0.001 versus baseline) and a low incidence of EPS-related adverse events (4.7%). CONCLUSION Results indicate that switching to quetiapine was clinically beneficial for patients with poor efficacy or intolerable side effects on their previous antipsychotic medication.
Keywords: Atypical Antipsychotic; Efficacy; Quetiapine; Schizophrenia; Tolerability.