Application of Computerized Adaptive Testing to the Foot and Ankle Ability Measure

Patient-reported outcome measures are an increasingly important tool for assessing the impact of treatments orthopedic surgeons render. Despite their importance, they can present a burden. We examined the validity and utility of a computerized adaptive testing (CAT) method to reduce the number of questions on the Foot and Ankle Ability Measure (FAAM), a validated anatomy-specific outcome measure.

A previously developed FAAM CAT system was applied to the responses of patients undergoing foot and ankle evaluation and treatment over a 3-year period (2017-2019). A total of 15 902 responses for the Activities of Daily Living (ADL) subscale and a total of 14 344 responses for the Sports subscale were analyzed. The accuracy of the CAT to replicate the full-form score was assessed.

The CAT system required 11 questions to be answered for the ADL subscale in 85.1% of cases (range, 11-12). The number of questions answered on the Sports subscale was 6 (range, 5-6) in 66.4% of cases. The mean difference between the full FAAM ADL subscale and CAT was 0.63 of a point. The mean difference between the FAAM Sports subscale and CAT was 0.65 of a point.

The FAAM CAT was able to reduce the number of responses a patient would need to answer by nearly 50%, while still providing a valid outcome score. This measure can therefore be directly correlated with previously obtained full FAAM scores in addition to providing a foot/ankle-specific measure, which previously reported CAT systems are not able to do.

Level IV, case series.