Validation of foot and ankle outcome score for hallux valgus.

BACKGROUND: Patient-reported outcome questionnaires such as the Foot and Ankle Outcome Score (FAOS) are useful in evaluating results after orthopedic interventions. However, despite being frequently used in the literature, its validity has not been established for forefoot disorders. Our study aimed to validate the FAOS for use in assessing outcomes of hallux valgus surgery.
METHODS: From 2006 to 2009, 195 patients with nonarthritic hallux valgus were included in the construct validity portion of the study. Patients had a SF-36 and a FAOS completed. Forty additional patients, both preoperative and postoperative, were given questionnaires to assess the relevance of each of the FAOS questions as it pertained to their bunions. Patients were also given the FAOS 1 month after the first to assess FAOS reliability. Responsiveness of the FAOS was included with 40 patients who had both preoperative and postoperative FAOS scores.
RESULTS: Four out of five FAOS subscales demonstrated acceptable correlation with the SF-36. The FAOS symptoms subscale showed the least correlation with SF-36, demonstrating the foot-specific nature of the questions. Both preoperative and postoperative patients rated the FAOS quality of life questions as the most relevant. All five subscales achieved acceptable test-retest reliability. The FAOS sports and recreation subscale was the least responsive.
CONCLUSION: Patient-based assessments have become increasingly important in evaluating treatment effectiveness. This study has shown that the FAOS has acceptable construct validity, reliability, and responsiveness in hallux valgus patients and is a useful patient-based tool in assessing these patients.