Predictors of Treatment-Resistant and Clozapine-resistant Schizophrenia

A 12-Year Follow-up Study of First-Episode Schizophrenia-Spectrum Disorders

Sherry Kit Wa Chan; Hei Yan Veronica Chan; William G. Honer; Tarun Bastiampillai; Yi Nam Suen; Wai Song Yeung; Ming Lam; Wing King Lee; Roger Man King Ng; Christy Lai Ming Hui; Wing Chung Chang; Edwin Ho Ming Lee; Eric Yu Hai Chen


Schizophr Bull. 2021;47(2):485-494. 

In This Article


The study found that 13% of FES patients followed up over 12 years were prescribed with clozapine and 15% were estimated to be TRS. The nested case-control study results suggest that neurodevelopmental factors, early clinical characteristics, and requirement for higher antipsychotic dose may all contribute to the TRS development, highlighting the heterogeneity and multiple pathways leading to this form of illness. Although the development of TRS was similar in the EIS group compared with the SCS group, delay in clozapine prescription, an important risk factor for the development of clozapine resistance, was shorter in the EIS group. This emphasized the need to establish specific interventions, including relapse prevention and an early clozapine prescription program during the first 1 to 2 years of illness, to potentially reduce the TRS rate and improve the outcomes of patients with TRS.