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Treatment-resistant schizophrenia (TRS) is a severe form of schizophrenia. From one fifth to one third of all patients with schizophrenia are resistant to treatment.
To determine the knowledge on TRS and to find out the extent and the quality of research on TRS.
To conduct a systematic review of the current literature on TRS.
Original studies and reviews on TRS were systematically collected from PubMed and Scopus databases. The following search strategy was used as a title search; (“ultra-resistant” OR “treatment-refractory” OR “treatment-resistant”) AND (schizophrenia). The search was restricted to English language articles.
The literature search identified 403 studies. After abstract and title review, 324 studies were included. The included studies considered medication (n 213), electroconvulsive therapy and repetitive transcranial magnetic stimulation (15), prognosis (15), genetics (15), studies on neurobiology (15), definitions (14), psychotherapy (12), brain structures and functioning (10), cognition (7) and other miscellaneous studies (6) on TRS. Definitions of TRS varied notably and in most of the non-pharmacological studies, the samples were fairly small. Regarding treatments, clozapine, ECT, and cognitive-behavioral therapy have shown effectiveness, though the quality of research on interventions is limited. Very little is known about risk factors and predictors of outcome in TRS.
Our findings suggest TRS is poorly studied and understood condition contrasted to its high prevalence, clinical importance and poor prognosis. There is a lack of studies on epidemiology, for example risk factors of TRS, as well as on outcomes and longitudinal course. Most of the studies considered medication.
The authors have not supplied their declaration of competing interest.