The SWITCH study: rationale and design of the trial
Evidence on sequential trial with atypical antipsychotics has been scarce. We conducted an algorithm-based antipsychotic pharmacotherapy. In this open-label study, patients with schizophrenia (DSM-IV) were treated with antipsychotic monotherapy, step-by-step, with each trial lasting up to 8 weeks. At baseline, they were highly symptomatic to score more than 54 in the total Brief Psychiatric Rating Scale (BPRS1–7) score. When the posttreatment BPRS score was above 70% of the baseline, they were subsequently treated with another and up to three atypicals. Basically, anticholinergics were prohibited, and only adjunctive allowed was lorazepam. The secondary endpoint was a clinical status good enough to be discharged for 66 inpatients and a successful continuation therapy with the same antipsychotic agent for more than 6 months for 12 outpatients. Three groups of 26 patients each were randomized to Olanzapine, Quetiapine, or Risperidone. Thirty-nine (50%) responded to the first agent (Olanzapine16, Quetiapine9, Risperidone14), and 14 responded to the second. Only two showed response to the third, and 16 failed to respond to all three antipsychotics, with only 7 dropouts. Overall, there were 22 Olanzapine, 14 Quetiapine, and 19 Risperidone responders. Based on the secondary outcome, 20 Olanzapine-treated (average maximum dose, 15.4 mg), 10 Quetiapine-treated (418 mg), and 20 Risperidone-treated (4.10 mg) patients responded. The difference in response as the first choice was significant (p < 0.05). Relative doses of those failing to respond were comparable (Olanzapine 18.3 mg, Quetiapine 564 mg, Risperidone5.47 mg). Extrapyramidal symptoms did not change significantly. When the first atypical antipsychotic is inadequate, switching to the second is worth trying, although some remain treatment-refractory. Quetiapine may be inferior to Olanzapine and Risperidone in symptomatic patients.