Awareness of illness moderates self-assessment of psychotic symptoms.

OBJECTIVE: Self-reports or patient-reported outcome measures are seldom used in psychosis due to concerns about the ability of patients to accurately report their symptomatology, particularly in cases of low awareness of illness. The aim of this study was to assess the effect of insight on the accuracy of self-reported psychotic symptoms using a computerized adaptive testing tool (CAT-Psychosis). METHODS: A secondary analysis of data drawn from the CAT-Psychosis development and validation study was performed. The Brief Psychiatric Rating Scale and the Scale of Unawareness of Mental Disorders were administered by clinicians. Patients completed the self-reported version of the CAT-Psychosis. Patients were median-split regarding their insight level to compare the correlation between the two psychosis severity measures. A subgroup sensitivity analysis was performed only on patients with schizophrenia spectrum disorders. RESULTS: A total of 159 patients with a psychotic disorder who completed both CAT-Psychosis and Scale of Unawareness of Mental Disorders were included. For the whole sample, CAT-Psychosis scores showed convergent validity with Brief Psychiatric Rating Scale ratings (r = 0.517, 95% confidence interval = [0.392, 0.622], p < 0.001). Insight was found to moderate this correlation (ß = -0.511, p = 0.005), yet agreement between both measures remained statistically significant for both high (r = 0.621, 95% confidence interval = [0.476, 0.733], p < 0.001) and low insight patients (r = 0.408, 95% confidence interval = [0.187, 0.589], p < 0.001), while psychosis severity was comparable between these groups (for Brief Psychiatric Rating Scale: U = 3057, z = -0.129, p = 0.897; disorganization: U = 2986.5, z = -0.274, p = 0.784 and for CAT-Psychosis: U = 2800.5, z = -1.022, p = 0.307). Subgroup of patients with schizophrenia spectrum disorders showed very similar results. CONCLUSIONS: Insight moderates the correlation between self-reported and clinician-rated severity of psychosis, yet CAT-Psychosis remains valid in patients with both high and low awareness of illness.

Development and Validation of a Computerized Adaptive Assessment Tool for Discrimination and Measurement of Psychotic Symptoms.

OBJECTIVE: Time constraints limit the use of measurement-based approaches in research and routine clinical management of psychosis. Computerized adaptive testing (CAT) can reduce administration time, thus increasing measurement efficiency. This study aimed to develop and test the capacity of the CAT-Psychosis battery, both self-administered and rater-administered, to measure the severity of psychotic symptoms and discriminate psychosis from healthy controls. METHODS: An item bank was developed and calibrated. Two raters administered CAT-Psychosis for inter-rater reliability (IRR). Subjects rated themselves and were retested within 7 days for test-retest reliability. The Brief Psychiatric Rating Scale (BPRS) was administered for convergent validity and chart diagnosis, and the Structured Clinical Interview (SCID) was used to test psychosis discriminant validity. RESULTS: Development and calibration study included 649 psychotic patients. Simulations revealed a correlation of r = .92 with the total 73-item bank score, using an average of 12 items. Validation study included 160 additional patients and 40 healthy controls. CAT-Psychosis showed convergent validity (clinician: r = 0.690; 95% confidence interval [95% CI]: 0.610-0.757; self-report: r = .690; 95% CI: 0.609-0.756), IRR (intraclass correlation coefficient [ICC] = 0.733; 95% CI: 0.611-0.828), and test-retest reliability (clinician ICC = 0.862; 95% CI: 0.767-0.922; self-report ICC = 0.815; 95%CI: 0.741-0.871). CAT-Psychosis could discriminate psychosis from healthy controls (clinician: area under the receiver operating characteristic curve [AUC] = 0.965, 95% CI: 0.945-0.984; self-report AUC = 0.850, 95% CI: 0.807-0.894). The median length of the clinician-administered assessment was 5 minutes (interquartile range [IQR]: 3:23-8:29 min) and 1 minute, 20 seconds (IQR: 0:57-2:09 min) for the self-report. CONCLUSION: CAT-Psychosis can quickly and reliably assess the severity of psychosis and discriminate psychotic patients from healthy controls, creating an opportunity for frequent remote assessment and patient/population-level follow-up.