2020 Roger A. Mann Award Winner: Application of Computerized Adaptive Testing to the Foot and Ankle Ability Measure

CATEGORY: Other INTRODUCTION/PURPOSE: Patient-reported outcome measures (PROMs) are an increasingly important tool for assessing the impact of treatments orthopaedic surgeons render to patients. They provide information directly reported by the patient pertaining to the perception of their own outcome, functional status, and quality of life. Despite their importance, they can present a burden for patients as well as for a busy outpatient clinic. The Foot and Ankle Ability Measure (FAAM) is a freely available validated anatomy-specific outcome measure consisting of 32 questions, and has been found to be reliable for patients with a wide spectrum of foot and ankle conditions. 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. METHODS: A previously developed FAAM CAT system was applied to the responses of patients undergoing foot and ankle evaluation and treatment at a busy tertiary referral orthopaedic practice 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 using the mean and standard deviation of scores for both groups (FAAM versus CAT), frequency distributions of the scores and score differences for both groups, Pearson and intraclass correlation coefficients, and Bland-Altman assessments of patterns in score differences. RESULTS: The CAT system required 11 questions to be answered for the ADL subscale in 85.1% of cases (compared to 22 questions for the FAAM) and 12 in 14.9% of cases. The number of questions answered on the Sports subscale was 6 in 66.4% of cases (compared to 10 for the FAAM) and 5 in 33.6% of cases. The mean difference between the full FAAM ADL subscale (out of 100 points) and CAT was 0.6266 of a point and scores were within 7.5 points in greater than 95% of cases. The mean difference between the FAAM Sports subscale (out of 100 points) and CAT was 0.5967 of a point and scores were within the minimal clinically important difference of 9 in greater than 95% of cases. CONCLUSION: 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.