Development of self-stigma inventory for patients with schizophrenia (SSI-P): reliability and validity study

OBJECTIVES: Internalizing the public stigma in patients with schizophrenia leads to self-stigmatization associated with a number of negative consequences such as depression, low self-esteem, hopelessness, impairment of social adaptation, unemployment, and treatment non-adherence. No instruments have been developed to assess the self-stigmatization for patients with schizophrenia living in Turkey. The purpose of this study was to develop a culturally-sensitive and easy-to-use instrument to measure self-stigma of the patients with schizophrenia and schizoaffective disorder. METHODS: After examining the existing stigma and self-stigma scales for people with mental illnesses, a 19-item self-stigma inventory was formed. Focus group interviews were conducted with patients with schizophrenia and the items were reviewed and rephrased into more comprehensible statements for the patients. The pilot study was conducted with a sample of 15 patients with schizophrenia, and the inventory was given its final form, self-stigma inventory for patients (SSI-P). Outpatients with schizophrenia and schizoaffective disorder were given sociodemographic form, SSI-P, Beck Depression Inventory (BDI), Internalized Stigma of Mental Illness (ISMI), Rosenberg Self-Esteem Scale (RSES), Beck Hopelessness Scale (BHS), Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression-Severity (CGI-S), and Global Assessment of Functioning (GAF). For reliability analyses; internal consistency, item-total correlation, and test-retest reliability were assessed. Validity analyses were conducted with Explanatory Factor Analysis and convergent validity. RESULTS: The sample of the study was 162 patients with schizophrenia and schizoaffective disorder of which 77% were males, 70% were single, mean age was 37, and level of education was 10 years. Cronbach’s alpha coefficient of the scale was 0.93 ranging among the subscales between 0.60 and 0.91. Kaiser-Meyer-Olkin value was 0.91, and the Barlett test was significant (p < 0.001) for explanatory factor analysis and three factors were found (perceived devaluation, internalized stereotypes and social withdrawal, concealment of the illness) that can explain 63.5% of the total variance. Two items were removed because of their low factor value, and the final form consisted of 17 items. SSI-P was highly correlated with commonly-used stigma scale ISMI (r = 0.73), and moderately correlated with BDI (r = 0.53), BHS (r = 0.40), and RSES (r = −0.59). It also showed low correlation with PANSS negative score (r = 0.19). The test-retest reliability coefficient of the scale was 0.83. CONCLUSION: SSI-P is a reliable and valid instrument for assessing the self-stigmatization of patients with schizophrenia and schizoaffective disorder. The scale is an easy-to-comprehend, user-friendly, and culturally-sensitive tool with its 17 items