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Background–objectivePrevalence data of cognitive impairment in Schizophrenia based on large population samples are scarce. Our goal is to relate cognition and functional outcomes, and estimate prevalence of cognitive impairment in a large sample of schizophrenia outpatients treated with second-generation antipsychotics.MethodA cross-sectional outpatient evaluation conducted during follow-up visits. Selection criteria included six-months stable treatment. The brief battery, EPICOG-SCH, covered four cognitive domains related to functional outcomes: working memory (WAIS-III-Letter-Number-Sequencing), executive function (Category Fluency Test; CFT), verbal memory (WMS-III-Logical-Memory), and information processing speed (Digit-Symbol-Coding and CFT). Clinical severity and functional impairment were assessed with CGI-SCH and WHO DAS-S. Impairment prevalence was calculated at ≤ 1.5 SD.ResultsAmong patients recruited (n = 848) in 234 participating centers, 672 were under 6-month treatment. 61.5% (n = 413) reported cognitive impairment according to CGI-SCH Cognitive Subscale. Estimated prevalences were 85.9% (95% CI 85.6–86.2%) CFT-Fruits; 68.3% (95% CI 67.8–68.8%) CFT-Animals; 38.1% (95% CI 37.5–38.3%) Digit-Symbol-Coding; 24.8% (95% CI 24.1–25.5%) Verbal Memory-Units; 20.9% (95% CI 20.2–21.6%) Letter-Number Sequencing; 11.7% (95% CI 11.0–12.4%) Verbal Memory-Items. Negative and Depressive symptoms, Deficit Syndrome, and functional disability were related to poor performance. Functional disability was predicted by CGI-SCH-Overall severity (OR = 1.34635, p < 0.0001), CGI-SCH-Negative Symptoms (OR = 0.75540, p < 0.0001), working memory (Letter-Number-Sequencing) (OR = − 0.16442, p = 0.0004) and the time-course (OR = 0.05083, p = 0.0094), explaining 47% of the observed variability.ConclusionMost prevalent impairments were on executive function and processing speed domains; however, working memory showed the strongest relationship to functional disability. Monitoring cognitive function during follow up is critical to understand patient’s everyday functional capacity.

Brief batteries in schizophrenia, are needed to screen for the cognitive impact of schizophrenia. We aimed to validate and co-norm the Epidemiological Study of Cognitive Impairment in Schizophrenia (EPICOG-SCH) derived brief cognitive battery. A cross-sectional outpatient evaluation was conducted of six-hundred-seventy-two patients recruited from 234 centers. The brief battery included well-known subtests available worldwide that cover cognitive domains related to functional outcomes: WAIS-III-Letter-Number-Sequencing-LNS, Category Fluency Test-CFT, Logical-Memory Immediate Recall-LM, and Digit-Symbol-Coding-DSC. CGI-SCH Severity and WHO-DAS-S were used to assess clinical severity and functional impairment, respectively. Unit Composite Score (UCS) and functional regression-weighted Composite Scores (FWCS) were obtained; discriminant properties of FWCS to identify patients with different levels of functional disability were analyzed using receiver-operating characteristic (ROC) technique. The battery showed good internal consistency, Cronbach's alpha = 0.78. The differences between cognitive performance across CGI-SCH severity level subscales ranged from 0.5 to 1 SD. Discriminant capacity of the battery in identifying patients with up to moderate disability levels showed fair discriminant accuracy with areas under the curve (AUC) > 0.70, p < 0.0001. An FWCS mean cut-off score ≥ 100 showed likelihood ratios (LR) up to 4.7, with an LR + of 2.3 and a LR − of 0.5. An FWCS cut-off ≥ 96 provided the best balance between sensitivity (0.74) and specificity (0.62).The EPICOG-SCH proved to be a useful brief tool to screen for the cognitive impact of schizophrenia, and its regression-weighted Composite Score was an efficient complement to clinical interviews for confirming patients' potential functional outcomes and can be useful for monitoring cognition during routine outpatient follow-up visits.

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