Development of an IRT-Based Short Form to Assess Applied Cognitive Function in Outpatient Rehabilitation

Item response theory and computerized adaptive testing methods allow the development of a large calibrated item bank from which different subsets of questions can be selected for administration and scored on a common scale. The objective of this study was to develop an outpatient rehabilitation self-report short form for the Activity Measure for Post-Acute Care Applied Cognition item bank.

Using data from a convenience sample of 235 rehabilitation outpatients, item content and item response theory-based test information function parameters were used in item selection. Internal consistency reliability, intraclass correlation coefficient (ICC), and percentage at the lowest (floor) and highest (ceiling) scores were evaluated for the short form and full item bank.

A 15-item short form was developed. The internal consistency of the short form was 0.86. The ICC3,1 for the short form and item bank was 0.97 (95% confidence interval, 0.94-0.98). No floor effects were noted, and ceiling effects were 27.66% (short form) and 26.38% (full item bank).

The Applied Cognition outpatient short form demonstrated acceptable psychometric properties and provides a bridge to item response theory-based measurement for settings where point-of-care computing is not available.