Finding Early Improvement Threshold to Predict Response After 8 Weeks of Treatment Using Risperidone in First-Episode Psychosis

PURPOSE/BACKGROUND: The study aims to assess whether the early response can predict the outcome at the endpoint for the treatment of first-episode psychosis with risperidone and identify the relationship between initial symptom reduction and late response. METHODS/PROCEDURES: A prospective observational study with 4 points follow-up (weeks 2, 3, 4, and 8) was conducted in 48 adult first-episode psychosis patients. Symptoms were quantified by the Positive and Negative Syndrome Scale (PANSS) score. The initial recommended dose was 2 mg of risperidone once daily before sleep. The PANSS score on day 1 (before initiation of drug therapy) was considered as the baseline score. Treatment responses were considered as a reduction of more than 20%, 25%, 30% and 50% from the baseline score on first, second, third, and final follow-up, respectively. Receiver operating characteristic curves were generated for predicting response at the endpoint. FINDINGS/RESULTS: Thirty-one (65%) patients achieved more than 50% reduction (responders) in PANSS score. The mean total PANSS score of the study population after 8 weeks of therapy was found to be 49.77 (95% confidence interval, 46.10-53.43). The mean percentage reduction in PANSS score after 8 weeks of therapy was found to be 52.92% (95% confidence interval, 48.83-57.01). Week 2 response can be taken as the early response (area under the curve = 81.9, P < 0.001). However, the more accurate prediction was possible with week 4 response (area under the curve = 88.7%, P < 0.001). IMPLICATIONS/CONCLUSIONS: Our study suggests that patients with an early response at week 2 are likely to achieve positive response after 8 weeks.