Validation of Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS) in Tamil and its Relationship with Objective Cognition and Psychopathology

Self-report of cognitive deficits in schizophrenia is potentially important in the planning of interventions related to functional outcome and individual therapy. Subjective scale to investigate cognition in schizophrenia (SSTICS) (Stip et al. in Comprehensive Psychiatry 44:331–340, 2003) is a 21 item self-administered scale that is simple and easy to use. It is specifically designed to evaluate subjective cognitive complaints of patients with schizophrenia. It seemed appropriate therefore to validate a Tamil version of this tool for use in patients diagnosed as schizophrenia in Southern India. The study aimed to validate the SSTICS for use in patients diagnosed as schizophrenia in South India and to evaluate the association between subjective and objective cognition. The first step was to adapt SSTICS to the vernacular language (Tamil). A focus group discussion with patients was conducted for the purpose of correcting the wording of the questions and for comments on the applicability of the questions. Patients, with the DSM IV diagnosis of Schizophrenia, (n = 191), fulfilling inclusion / exclusion criteria were recruited from the outpatient department of Schizophrenia Research Foundation, Chennai. A subgroup of 78 subjects were assessed using objective tests for memory, attention and executive functions and psychopathology was assessed using Positive and Negative Symptom Scale (PANSS). Data collected were analysed using SPSS, version 16. Face validity of the Tamil version was established. Internal consistency was found to be good (0.851). Test–retest reliability was assessed and spearman’s correlation coefficient was r =.766, Factor analysis was performed to establish the construct validity of the tool which identified 6 major factors. Correlation between SSTICS and objective cognitive domains found no significant association. The sensitivity and specificity analysis revealed attention domain related questions were more specific and sensitive when compared to other domains. SSTICS, in the Tamil version, appears to be a valid tool to screen for cognitive deficits based on subjective reports. Persons with schizophrenia are able to evaluate subjective cognitive performance in the context of everyday functioning. This can lend itself to the planning of appropriate interventions, despite the lack of corelation to objective measures. © The Author(s), under exclusive licence to Springer Nature India Private Limited 2023.