BACKGROUND: Up to 50% of first-episode psychosis patients suffer from long-term incomplete remission or treatment resistance. Different definitions for these terms have been used in psychiatric research, making generalized statements about the prevalence and predictors of treatment resistance difficult. OBJECTIVE: The aim of this study was to give an overview on state-of-the-art definitions of treatment resistance for each of the diagnoses making up the inhomogeneous diagnostic entity 'psychosis' and to analyze the factors leading to treatment resistance. METHODS: A computerized and manual literature search for relevant articles published within recent years was undertaken. RESULTS: In addition to symptomatic criteria, patients' functional level and quality of life have to be considered in the definition of treatment resistance. Patient-related, illness-related and treatment-related predictors of treatment resistance and incomplete remission might help to identify subjects at risk and optimize interventions.
