Measurement Precision and Efficiency of Computerized Adaptive Testing for the Activities-specific Balance Confidence Scale in People With Stroke

Objective Administrative burden often prevents clinical assessment of balance confidence in people with stroke. A computerized adaptive test (CAT) version of the Activities-specific Balance Confidence Scale (ABC CAT) can dramatically reduce this burden. The objective of this study was to test balance confidence measurement precision and efficiency in people with stroke with an ABC CAT. Methods We conducted a retrospective, cross-sectional, simulation study with data from 406 adults approximately 2 months post-stroke in the Locomotor-Experience Applied Post-Stroke trial. Item parameters for CAT calibration were estimated with the Rasch model using a random sample of participants (n = 203). Computer simulation was used with response data from the remaining 203 participants to evaluate the ABC CAT algorithm under varying stopping criteria. We compared estimated levels of balance confidence from each simulation to actual levels predicted from the Rasch model (Pearson correlations and mean standard error [SE]). Results Results from simulations with number of items as a stopping criterion strongly correlated with actual ABC scores (full item, r = 1, 12-item, r = 0.994; 8-item, r = 0.98; 4-item, r = 0.929). Mean SE increased with decreasing number of items administered (full item, SE = 0.31; 12 item, SE = 0.33; 8 item, SE = 0.38; 4 item, SE = 0.49). A precision-based stopping rule (mean SE = 0.5) also strongly correlated with actual ABC scores (r = 0.941) and optimized the relationship between number of items administrated with precision (mean number of items 4.37, range [4–9]). Conclusion An ABC CAT can determine accurate and precise measures of balance confidence in people with stroke with as few as 4 items. Individuals with lower balance confidence may require a greater number of items (up to 9) which could be attributed to the Locomotor-Experience Applied Post-Stroke trial excluding more functionally impaired persons. Impact Computerized adaptive testing can drastically reduce the ABC test’s administration time while maintaining accuracy and precision. This should greatly enhance clinical utility, facilitating adoption of clinical practice guidelines in stroke rehabilitation. Lay Summary If you have had a stroke, your physical therapist will likely test your balance confidence. A CAT version of the ABC scale can accurately identify balance with as few as 4 questions, which takes much less time.