Background
schizophrenia
Antipsychotic drugs are the main treatment method for schizophrenia. However, the effectiveness of this therapy in clinical practice is unsatisfactory; 19.8–66.9% of patients with schizophrenia do not or only partially respond to antipsychotic in 4–6 weeks [The assertions in treatment guidelines continue to be diverse and commonly lack sufficient supportive evidence. The World Federation of Societies of Biological Psychiatry (WFBSP) gave a wide range of 2–8 weeks at the recommended dose before switching medication [Baseline severity of schizophrenia has been reported to influence the response to antipsychotics that patients with more severe initial symptoms tend to experience greater reductions in symptoms [Besides the baseline severities of illness, the type of antipsychotics also plays a role in predicting early nonresponse in subsequent treatment nonresponse. For instance, one study focusing on acute-phase schizophrenia with the definition of early response as a Clinical Global Impressions-Improvement Scale (CGI-I) ≤ 3 after 2 weeks of treatment found that response to risperidone at 2 weeks can effectively predict long-term treatment response, whereas olanzapine required 4 weeks [In this study, we investigate whether early phase treatment response on weeks 2 and 4 could predict therapeutic outcome at week 8 using data from a large multicenter, open-label clinical trial. Secondly, we defined mild, moderate, and severe schizophrenia by PANSS and aimed to investigate the optimum predictive cut-off value defining early non-response in subgroups with different baseline severities of illness. Thirdly, we investigate whether the cut-off value is consistent in different atypical antipsychotic drugs (olanzapine, risperidone, amisulpride, and aripiprazole).