Predictors of treatment resistant schizophrenia-spectrum disorder: 10-year retrospective study of first-episode psychosis

Abstract

BACKGROUND: Schizophrenia is a serious mental illness that affects approximately 1% of the general population. While pharmacological treatment has been the main intervention for patients, evidence has suggested that around 20–30% of patients do not respond to antipsychotic medication and are considered as treatment resistant. The present study aimed to explore the prevalence and patterns of treatment resistant schizophrenia, and predictive factors associated with its development. METHODS: Seven hundred patients with first-episode psychosis (Mage: 34.92, SD: 3.74) presented to the Early Intervention Service in Hong Kong from January 1998 August 2003 were studied. Socio-demographics, duration of untreated psychosis, age of first presentation and medication history were collected via systematic medical file review. Treatment resistant status was defined as ever been treated with Clozapine. RESULTS: Of all 700 patients studied, 69 (9.9%) are treatment resistant. Of the 69 patients, 2 (0.3%) were recorded dead. Logistic regression analysis revealed that age of first presentation (p = 0.001), number of relapse during the first three years (p < 0.001) and duration of atypical antipsychotics prescription over the initial three years (p < 0.05) reliably predicted clozapine status. CONCLUSION: The preliminary results showed that younger age of first onset, more number of relapse and longer duration of atypical antipsychotics prescription over the initial three years are associated with increased risk of developing treatment-resistant. These suggested the contribution of both neurodevelopmental and neurodegenerative factors. Further studies should focus on detail understanding of the role of these factors in the longitudinal progression of the illness.