Background: The field of foot and ankle surgery lacks a widely accepted gold-standard patient-reported outcome instrument. With the changing infrastructure of the medical profession, more efficient patient-reported outcome tools are needed to reduce respondent burden and increase participation while providing consistent and reliable measurement across multiple pathologies and disciplines. The primary purpose of the present study was to validate 3 Patient-Reported Outcomes Measurement Information System computer adaptive tests (CATs) most relevant to the foot and ankle discipline against the Foot and Ankle Outcome Score (FAOS) and the Short Form 12 general health status survey in patients with 6 common foot and ankle pathologies.
Methods: Patients (n = 240) indicated for operative treatment for 1 of 6 common foot and ankle pathologies completed the CATs, FAOS, and Short Form 12 at their preoperative surgical visits, 1 week subsequently (before surgery), and at 6 months postoperatively. The psychometric properties of the instruments were assessed and compared.
Results: The Patient-Reported Outcomes Measurement Information System CATs each took less than 1 minute to complete, whereas the FAOS took 6.5 minutes, and the Short Form 12 took 3 minutes. CAT scores were more normally distributed and had fewer floor and ceiling effects than those on the FAOS, which reached as high as 24%. The CATs were more precise than the FAOS and had similar responsiveness and test-retest reliability. The physical function and mobility CATs correlated strongly with the activities subscale of the FAOS, and the pain interference CAT correlated strongly with the pain subscale of the FAOS. The CATs and FAOS were responsive to changes with operative treatment for 6 common foot and ankle pathologies.
Conclusions: The CATs performed as well as or better than the FAOS in all aspects of psychometric validity. The Patient-Reported Outcomes Measurement Information System CATs show tremendous potential for improving the study of patient outcomes in foot and ankle research through improved precision and reduced respondent burden.
Level of evidence: Level II, prospective comparative study.
Keywords: FAOS; computer adaptive tests; foot and ankle pathology; outcome studies; patient reported outcome; psychometric properties.