The Manchester–Oxford Foot Questionnaire (MOXFQ) is a validated
16-item, patient-reported outcome measure for evaluating outcomes
of foot or ankle surgery. The original development of the instrument
identified three domains. This present study examined whether the
three domains could legitimately be summed to provide a single summary
index score. The MOXFQ and Short-Form (SF)-36 were administered to 671 patients
before surgery of the foot or ankle. Data from the three domains
of the MOXFQ (pain, walking/standing and social interaction) were
subjected to higher order factor analysis. Reliability and validity
of the summary index score was assessed.Objectives
Methods
The responsiveness of the Manchester–Oxford Foot
Questionnaire (MOXFQ) was compared with foot/ankle-specific and
generic outcome measures used to assess all surgery of the foot
and ankle. We recruited 671 consecutive adult patients awaiting
foot or ankle surgery, of whom 427 (63.6%) were female, with a mean
age of 52.8 years (18 to 89). They independently completed the MOXFQ,
Short-Form 36 (SF-36) and EuroQol (EQ-5D) questionnaires pre-operatively
and at a mean of nine months (3.8 to 14.4) post-operatively. Foot/ankle
surgeons assessed American Orthopaedic Foot and Ankle Society (AOFAS)
scores corresponding to four foot/ankle regions. A transition item measured
perceived changes in foot/ankle problems post-surgery. Of 628 eligible
patients proceeding to surgery, 491 (78%) completed questionnaires
and 262 (42%) received clinical assessments both pre- and post-operatively. The
regions receiving surgery were: multiple/whole foot in eight (1.3%),
ankle/hindfoot in 292 (46.5%), mid-foot in 21 (3.3%), hallux in
196 (31.2%), and lesser toes in 111 (17.7%). Foot/ankle-specific
MOXFQ, AOFAS and EQ-5D domains produced larger effect sizes (>
0.8)
than any SF-36 domains, suggesting superior responsiveness. In analyses
that anchored change in scores and effect sizes to patients’ responses
to a transition item about their foot/ankle problems, the MOXFQ
performed well. The SF-36 and EQ-5D performed poorly. Similar analyses,
conducted within foot-region based sub-groups of patients, found
that the responsiveness of the MOXFQ was good compared with the
AOFAS. This evidence supports the MOXFQ’s suitability for assessing
all foot and ankle surgery.