Outcome Assessment Performance of the SF-36, Manchester-Oxford Foot Questionnaire and AOFAS in Forefoot Reconstruction Surgery

Abstract

The purpose of this study was to investigate the measurement properties of the Short Form 36 (SF-36) to detect real change after forefoot reconstruction surgery. Responsiveness and minimally important change estimates were compared with those from the Manchester-Oxford Foot Questionnaire (MOXFQ) and the American Orthopaedic Foot and Ankle Society (AOFAS) measures. Eighty-three patients awaiting surgery were recruited. Patients completed pre- and 12 months postoperative the SF-36 and the MOXFQ. A surgeon assessed the AOFAS scores. The responsiveness to change was determined using the effect size (ES), the minimal detectable change (MDC) and the minimal clinically important change. Two subscales of the SF-36 demonstrated significant improvement, bodily pain (BP) and mental health. Only the BP domain appeared the most responsive with an ES of 0.73. All domains of the MOXFQ and AOFAS produced much larger effect sizes (ES > 1.5). MDC values for the majority of the SF-36 domains fell within measurement error except for the BP domain. Fewer patients showed significant improvement when compared with the MOXFQ pain domain. In conclusion, the SF-36 measuring tool proved to be neither reliable nor responsive enough to detect real change after forefoot surgery. Though the BP domain appeared to be the most responsive, it failed to detect meaningful change when compared to the MOXFQ-Pain and the Visual Analogue Scale.

Keywords: PROMS; clinical outcomes; forefoot surgery; hallux valgus; responsiveness.