Assessing the inter-rater reliability of the Schizophrenia Cognition Rating Scale: a non-interventional quantitative study.

Background: Cognitive impairment is a core feature of schizophrenia, profoundly impacting patients' functional abilities. As such, evaluating cognition-related functional activity/impairment is essential for identifying effective treatments. This study presents findings from a non-interventional quantitative study to assess the inter-rater reliability (IRR) of the Schizophrenia Cognition Rating Scale (SCoRS) with a sample representative of clinical trial populations.

Methods: Structured, one-to-one, 10-15-minute live interviews with patients with schizophrenia were conducted by trained SCoRS interviewers (raters), and a separate interview was then conducted with the patient's study partner (informant). Both interviews were recorded so that each interview was assessed by three different SCoRS raters in total (one live, two via recording). IRR was assessed using interclass correlation (ICC) and categorized as low (<0.70), good (0.70-0.90), or excellent (>0.90).

Results: A total of 44 patients with schizophrenia were evaluated by 12 raters (overall). The SCoRS Total Score (mean [SD]: 41.4 [10.2]) indicated moderate-to-moderately-severe impairment of cognition-related functioning, with high inter-patient variability. The SCoRS Total Score demonstrated excellent IRR, with an ICC of 0.91 (95% CI 0.88-0.95).

Conclusion: The 20-item SCoRS Total Score demonstrated excellent IRR in assessing cognition-related functional capacity in patients with schizophrenia, supporting its use as an endpoint in clinical studies.