LAUSR

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.