Minimally important change was estimated for the Manchester-Oxford Foot Questionnaire after foot/ankle surgery.
OBJECTIVE
To ascertain the smallest amounts of change for the three Manchester-Oxford Foot Questionnaire (MOXFQ) domains that are likely to be clinically meaningful and beyond measurement error for conditions affecting the foot/ankle. Estimates were compared with those from the Short-Form 36 (SF-36).


METHODS
A prospective observational study of 671 consecutive patients undergoing foot or ankle surgery at an orthopedic hospital. Before and 9 months after surgery, patients completed the MOXFQ and SF-36; transition items (anchor) asked about perceived changes in foot/ankle pain or problems since the surgery.


RESULTS
Four hundred ninety-one patients completed pre- and postoperative questionnaires. Anchor-based minimal clinically important change (MCIC) values were ~13 points for each of the MOXFQ Walking/standing (W/S), Pain, and Social Interaction (S-I) domains [and greater than the standard error of measurement (SEM)]. MCIC values for all SF-36 domains fell within the SEM. Between-group MCIDs for the MOXFQ were W/S, 16.2; Pain, 9.9; S-I, 9.3. Distribution-based minimal detectable change (MDC90) values for the MOXFQ were ~11, ~12, and ~16 score points for the W/S, Pain, and S-I scales, respectively.


CONCLUSIONS
This article provides information for aiding the interpretability of MOXFQ outcomes data and for planning future studies. The SF-36 is not recommended as a primary outcome for foot/ankle surgery.
Nuffield Department of Population Health, University of Oxford, Old Road Campus, Headington, Oxford OX3 7LF, UK; Department of Sport & Health Sciences, Oxford Brookes University, Jack Straw's Lane, Oxford OX3 OFL, UK. Electronic address: jill.dawson@dph.ox.ac.uk.
Jill
J
Dawson
Nuffield Department of Population Health, University of Oxford, Old Road Campus, Headington, Oxford OX3 7LF, UK.
Irene
I
Boller
Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Helen
H
Doll
Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD, UK.
Grahame
G
Lavis
Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD, UK.
Robert
R
Sharp
Nuffield Orthopaedic Centre, Windmill Road, Oxford OX3 7LD, UK.
Paul
P
Cooke
Nuffield Department of Population Health, University of Oxford, Old Road Campus, Headington, Oxford OX3 7LF, UK.
Crispin
C
Jenkinson
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D005528:Foot / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D055815:Young Adult
Foot and ankle; MOXFQ; Minimally important; Outcomes; SF-36; Surgery