Does early antipsychotic response predict long‐term treatment outcome?

OBJECTIVE: Early antipsychotic response within the first 2-3 weeks of treatment can predict short-term outcomes after several months. We conducted the current study to determine whether the predictive value of early antipsychotic response persists throughout long-term treatment over multiple years. METHODS: In this observational study, we conducted follow-up assessments of 64 patients with first-episode psychosis an average of 25 months after they began antipsychotic treatment. Patients were initially randomized to receive haloperidol or olanzapine, but treatment after the acute hospitalization period was not controlled. Regression analyses were used to determine whether early improvement on the Brief Psychiatric Rating Scale at 2 or 3 weeks predicted longer term improvement at follow-up. We conducted secondary analyses to determine whether early response could predict extrapyramidal side effects at follow-up. RESULTS: Early response to haloperidol at 2 weeks predicted Brief Psychiatric Rating Scale improvement on longer term follow-up (p = .002). Longer term improvement was not predicted by early response to olanzapine at 2 weeks (p = .726) or 3 weeks (p = .541). Rates of extrapyramidal side effects did not differ between treatment groups and were not predicted by early response. CONCLUSION: These results demonstrate the long-term prognostic value of early haloperidol response. The predictive value of early olanzapine response may be less robust.