The Manchester-Oxford Foot Questionnaire (MOxFQ)
The Manchester-Oxford Foot Questionnaire (MOXFQ) is a 16-item Patient Reported Outcome (PRO) measure developed and validated for use in studies assessing outcome following foot and/or ankle corrective surgery.
Foot and ankle surgery accounts for approximately one fifth of orthopaedic practice and has a high level of patient dissatisfaction. The Manchester-Oxford Foot Questionnaire’s (MOXFQ’s) are 16-item Patient Reported Outcome (PRO) measures developed and validated for use in clinical trials involving foot surgery. These self-administered PROs assesses how foot problems impair health-related quality of life can be completed before and after surgery.
The original MOXFQ (foot) PRO was developed as an outcome measure of hallux valgus (bunions) corrective surgery and has recently been slightly amended and validated for use among patients with a variety of foot or ankle problems. The MOXFQ (foot) and the MOXFQ (foot and ankle) PROs are available for license through iOutcomes.
The MOXFQ PROs were developed by researchers in the University of Oxford using interviews with patients and partially drawing on a pain related foot disability measure, the Manchester Foot Pain and Disability Index (MFPDI), as a template for item generation and content. The MFPDI is also available through iOutcomes.
Attributes of the MOXFQ PROs include
The MOXFQ PROs have been rigorously tested to demonstrate good content and construct validity.
The MOXFQ PROs exhibit good internal consistency. The MOXFQ (foot and Ankle) has also demonstrated good test-retest reliability within different foot and ankle surgical subgroups at baseline assessment.
Ability to detect change
The MOXFQ PROs are responsive to change. Evidence suggests that these PROs are likely to show more sensitivity to patients undergoing hallux valgus surgery or foot and ankle surgery compared to generic health measures.
Pre-testing and high completion rates suggest the PROs are easy to complete and acceptable within the test population.
All three scales in the MOXFQ (foot) PRO conform to Rasch measurement principles indicating unidimensional, equal interval scales.
Endorsed by the British Foot and Ankle Society to measure surgical outcome.
Summary Index Score
A recent paper (Morley et al. Bone Joint Research 2013;2:66–9, full reference below) concluded that analyses of data from the MOxFQ can also be presented in summary form, namely a single summary index score based on the sum of the three domains. This MOxFQ Summary Index provides and overall indication of the outcomes of foot and ankle surgery and satisfies the demands of healthcare professionals to have a single, simple indicator score of outcome.
The MOXFQ PROs are self-administered, paper based measures consisting of 16-items. The PROs measure three domains:
- Walking/standing (7 items)
- Pain (5 items)
- Social interaction (4 items)
Response options consist of a 5 point Likert scale ranging from no limitation to maximum limitation.
Developers’ of the PROs recommend using the MOXFQ (foot) questionnaire for clinical trials that are specifically investigating outcomes of interventions for hallux valgus correction and use of the MOXFQ (foot and ankle) in all other instances. For example, trials of surgery or audits of outcomes involving all other foot or ankle condition (this may include people with hallux valgus).
Scores for each domain are calculated by summing the responses to each item within a given domain. Raw scores can be converted to a 0-100 metric where 100=most severe. As mentioned above, the domains can also be summed to give a Summary Index score.
The MOFOX PROs were developed in a multistage process consistent with industry best practice:
Phase 1: Incorporating the patient’s perspective in order to understand the domain under investigation (Content validity)
Review of relevant literature revealed a potentially suitable PRO (the Manchester Foot Pain and Disability Index - also available from iOutcomes) which could be adapted and tested for use within in the hallux valgus surgical context.
Interviews exploring problems associated with hallux valgus were conducted with 10 out-patients attending hospital surgical clinics. Patients were asked to comment on questionnaire items and revisions were made to encompass pain severity within the measure. The amended questionnaire was piloted on seven patients for acceptability.
Phase 2: Establishing validity, reliability and responsiveness
The MOXFQ (foot) questionnaire and an established generic reference measure (the SF-36) were completed by 100 patients four weeks before undergoing surgery and again at 12 months post-surgery. A clinical examination by a foot surgeon or consultant surgical podiatrist was also carried out on both occasions.
Factor analysis confirmed three domains within the PRO (Walking/standing, Pain, Social Interaction). Two of the three domains (Walking/standing and Pain) conform to Rasch principles and represent unidimensional scales.
The MOXFQ (foot) domains ‘Walking/standing’ and ‘Pain’ showed high correlation (convergent validity) with similar domains found on the SF-36 and clinical foot assessment scores. Divergent validity was evident through low correlations with domains believed to be unrelated on the MOXFQ (foot) and the SF-36.
The three scales identified during factor analysis have shown good internal consistency with Cronbach’s alpha coefficients: Walking/standing (0.92), Pain (0.86) and Social Interaction (0.73)
The MOXFQ foot specific PRO detected significant changes in mean scores from before and after surgery showing sensitivity to change. Higher effect sizes were detected on the MOXFQ (foot) compared to the SF-36 indicating this condition specific PRO is more precise at measuring change.
The MOXFQ (foot and ankle)
The MOXFQ (foot and ankle) PRO was reevaluated in a study of 671 consequtive patients undergoing foot or ankle surgery. Here, all measurement properties were confirmed as good and good test-retest reliability, with ICCs all ≥0.89.
The MOXFQ PROs can be used to assess outcomes of foot and ankle surgery. The MOXFQ (foot) has been used in clinical studies and prospective cohort studies. It is expected the more recent MOXFQ (foot and ankle) will also be employed in similar studies.
Examples of studies carried out with the MOXFQ (foot) PRO:
Clinical audit of patients undergoing surgical repair of hallux valgus
Maher AJ,Kilmartin TE. Patient reported outcomes following the combined rotation Scarf and Akin’s osteotomies in 71 consecutive cases. Foot 2010.
Prospective cohort study
Harrison T, Fawzy E, Dinah F, Palmer S. Prospective assessment of dorsal cheilectomy for hallux rigidus using a patient-reported outcome score. J Foot Ankle Surg 2010; 49:232–7.