Onset and persistence of antipsychotic response in patients with schizophrenia.

In daily practice, clinicians are interested in knowing when to expect treatment response after initiating a new antipsychotic medication. This analysis examined whether response onset and persistence can distinguish true drug from placebo responses. The methodology proposed by Quitkin et al (1984) was applied to data from three 6-week double-blind placebo-controlled trials in schizophrenia to examine response (> or =30% Positive and Negative Syndrome Scale total score reduction from baseline) here using the antipsychotic paliperidone extended release (3-12 mg/d) versus placebo. Response patterns were categorized by persistence (persistent: response at every time point from first response to end point for > or =2 time points; nonpersistent: other patterns) and onset (early: first response at day 4 to week 2; later: week 3 to end point). Persistent responses occurred in 39.8% of antipsychotic-treated patients and in 20.2% of subjects receiving placebo (P < 0.001). An early persistent response was achieved in 23.5% of those who received antipsychotic medication and by 14.2% of the subjects who received placebo, and a later persistent response was achieved in 16.3% and in 6.0%, respectively (P < 0.001 for both comparisons). A nonpersistent response occurred in 16.9% and in 18.1%, respectively (P = 0.631). No response occurred in 37.1% of the antipsychotic-treated patients and in 58.6% of the placebo-treated subjects over 6 weeks (P < 0.001). In conclusion, persistent response (occurring either early or later) is more likely achieved with antipsychotic medication than with placebo, and response patterns may be useful in assessing true drug response. Results suggest that persistent response requires continuing antipsychotic treatment beyond 2 weeks in some patients. These results may be useful for clinical decision making and patient education.