• Orthopaedics Clinical Trials
• Foot & Ankle Conditions

• Orthopaedics Clinical Trials
• Foot & Ankle Conditions
• Orthopaedics

There is a tangible need for improved tools to measure patient outcomes after treatment of foot and ankle disorders. Numerous clinical outcome measures are used to evaluate foot and ankle disorders and procedures, but consensus on these measures has not been reached. Evidence of validity, reliability, and responsiveness for foot and ankle disorders has been published only for a few scores designed for foot and ankle patient-reported outcome (PRO) measures. Of these few scores, only the Foot Function Index (FFI) and Foot and Ankle Ability Measure (FAAM) have been used in published studies ≥ 5 times in the last decade [Hunt KJ, Hurwit D. J Bone Joint Surg Am. 2013; Martin et al. J Orthop Sports Phys Ther. 2007].

The Patient-Reported Outcomes Measurement Information (PROMIS) physical function computerized adaptive testing (PF CAT) has been validated for orthopaedic patients, as well as for lower extremity patients specifically [Hung M et al. Foot Ankle Int. 2013]. However, the responsiveness of the PF CAT has not been determined in foot and ankle patients. This study, presented by Kenneth J. Hunt, MD, Stanford University, Stanford, California, USA, compared the psychometric properties and efficiency of the PF CAT with the FAAM and FFI.

Ten participating US sites enrolled 328 patients undergoing ankle, hindfoot, or forefoot surgery. Preoperative and 6-month PROs were collected through the National Orthopaedic Foot and Ankle Outcomes Research Network using the FAAM, FFI, and PF CAT.

The patients underwent surgery for ankle instability, ankle arthritis, hallux valgus, hammertoe, hallux rigidus, and flatfoot; 56% completed the 6-month surveys. Construct validity, determined using the Rasch model, was high for all 3 instruments. Pearson correlations showed that the PF CAT was highly correlated with the FFI 5-point verbal rating scale (FFI-5pt) (r = 0.685) and the FAAM Activity of Daily Living subscale (FAAM_ADL) (r = 0.792). All 3 measures demonstrated excellent item reliability, suggesting that the order of item difficulty would be comparable across various patient samples. Person reliability was also high, suggesting similar ordering of individuals' function levels with repeated measures (Table 1).

Paired t tests showed that the PF CAT had a preoperative responsiveness measure of −1.6965 and a postoperative responsiveness measure of −0.2476, resulting in a change score of 1.44888 (95% CI, 0.47119 to 2.42657; t = 2.930; P = .004; Figure 1).

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Figure 1.

Psychometric Properties

CAT, computer adaptive testing.Reproduced with permission from KJ Hunt, MD.

For the FAAM_ADL, the preoperative (1.2693) and postoperative (3.9964) measures resulted in a change score of 2.72717 (95% CI, 2.19813 to 3.25620; t = 10.207; P = .000). Both the PF CAT and FAAM_ADL change scores indicated that patients had significantly improved physical function at 6 months.

The FFI-5pt had a preoperative measure of 0.4866 and a postoperative measure of 0.1828, resulting in a change score of −0.30381 (95% CI, −0.58721 to −0.02040; t = −2.120; P = .036), indicating that patients had significantly deteriorated function at 6 months. All 3 instruments were responsive to change, but the FFI-5pt change was in the opposite direction.

The item counts (number of questions) for the 3 instruments were 4.3 for the PF CAT, 28.0 for the FAAM, and 23.0 for the FFI. Patients completed the PF CAT in 44 seconds, the FAAM_ADL in 179 seconds, and the FFI-5pt in 194 seconds, showing that the PF CAT was significantly more efficient than both other measures (P < .000).

Dr Hunt concluded that the PROMIS PF CAT allows for consistent outcomes assessment across orthopaedic subspecialties, while providing a high degree of precision and efficiency. However, it is important to remember that physical function is not the only domain to measure; mental and social health can also affect disease burden and outcomes, and should be considered during outcomes assessment.

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