Early predictors of a clinical response at 8 weeks in patients with first-episode psychosis treated with paliperidone ER

Identification of early clinical markers that predict later treatment outcomes in first-episode psychosis is highly valuable. The present study was conducted to determine the best time at which to predict the late treatment response in first-episode psychosis patients treated with paliperidone extended release (ER), the factors predicting early treatment responses (at Week 2 and Week 3) and the relationships between the paliperidone ER plasma concentrations at Week 2 and Week 3, and the treatment responses at Week 2, Week 3 and Week 8. Various criteria for assessing treatment response were employed. We determined the plasma paliperidone concentrations at Week 2 and Week 3, using validated high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS). The treatment response at Week 3 optimally predicted the later (Week 8) response, in terms of negative predictive value (NPV). Independent predictors for good treatment responses at Week 2 and Week 3 were: Female gender, a higher educational level, a higher Positive and Negative Syndrome Scale (PANSS) excited score, and/or a shorter duration of untreated psychosis (DUP). The plasma paliperidone concentration at Week 3, but not Week 2, was a significant predictor of the late treatment response at Week 8. These results may help appropriate clinical decision-making for early non-responders after having their first episode of psychosis.