Defining treatment-resistant schizophrenia and response to antipsychotics: A review and recommendation

Treatment-resistant schizophrenia (TRS) has been defined mainly by severity of (positive) symptoms and response to antipsychotics derived from a relative change in the representative scales (most frequently ≥. 20% decrease in the Positive and Negative Syndrome Scale: PANSS), but these definitions have not necessarily been consistent. Integrating past evidence and real-world practicability, we propose that TRS be defined by at least two failed adequate trials with different antipsychotics (at chlorpromazine-equivalent doses of ≥. 600. mg/day for ≥. 6 consecutive weeks) that could be retrospective or preferably include prospective failure to respond to one or more antipsychotic trials. In addition, our proposed criteria require both a score of ≥. 4 on the Clinical Global Impression (CGI)-Severity and a score of ≤. 49 on the Functional Assessment for Comprehensive Treatment of Schizophrenia (FACT-Sz) or ≤. 50 on the Global Assessment of Functioning (GAF) scales to define TRS. Once TRS is established, we propose that subsequent treatment response be defined based on a CGI-Change score of ≤. 2, a ≥. 20% decrease on the total PANSS or Brief Psychiatric Rating Scale (BPRS) scores, and an increase of ≥. 20 points on the FACT-Sz or GAF. While these suggestions provide a pragmatic framework for TRS classification, they need to be tested in future trials.