Objective:: This study aimed to evaluate the validity of the Evaluation of Cognitive Processes involved in Disability in Schizophrenia scale (ECPDS) to discriminate for cognitive impairment in schizophrenia.
Design:: This multicentre cross-sectional study used a validation design with receiver operating characteristic (ROC) curve analysis.
Settings:: The study was undertaken in a French network of seven outward referral centres.
Subjects:: We recruited individuals with clinically stable schizophrenia diagnosed based on the Structured Clinical Interview for assessing Diagnostic and Statistical Manual of Mental Disorders (4th ed., rev.; DSM-IV-R) criteria.
Main measures:: The index test for cognitive impairment was ECPDS (independent variable), a 13-item scale completed by a relative of the participant. The reference standard was a standardized test battery that evaluated seven cognitive domains. Cognitive impairment was the dependent variable and was defined as an average z-score more than 1 SD below the normative mean in two or more cognitive domains.
Results:: Overall, 97 patients were included (67 with schizophrenia, 28 with schizoaffective disorder, and 2 with schizophreniform disorder). The mean age was 30.2 (SD 7.7) years, and there were 75 men (77.3%). There were 59 (60.8%) patients with cognitive impairment on the neuropsychological battery, and the mean ECPDS score was 27.3 (SD 7.3). The ROC curve analysis showed that the optimal ECPDS cut-off was 29.5. The area under the curve was 0.77, with 76.3% specificity and 71.1% sensitivity to discriminate against cognitive impairment.
Conclusion:: The ECPDS is a valid triage tool for detecting cognitive impairment in schizophrenia, before using an extensive neuropsychological battery, and holds promise for use in everyday clinical practice.
Keywords: Chronic disability; cognitive impairment; psychiatric rehabilitation; schizophrenia; sensitivity; specificity.