Comparison of the responsiveness of the Foot Health Status Questionnaire and the Manchester Foot Pain and Disability Index in older people

BACKGROUND In recent years, several questionnaires have been developed for the assessment of foot health and its impact on quality of life. In order for these tools to be useful outcome measures in clinical trials, their ability to detect change over time (responsiveness) needs to be determined. Therefore, the aim of this study was to assess the responsiveness of two commonly-used questionnaires in older people with foot pain. METHODS Participants (n = 59; 24 women and 35 men, mean age [SD] 82.3 [7.8] years) allocated to the intervention arm of a randomised controlled trial assessing the effectiveness of extra-depth footwear compared to usual care completed the Foot Health Status Questionnaire (FHSQ) and Manchester Foot Pain and Disability Index (MFPDI) at baseline and 16 weeks. Responsiveness of the FHSQ subscales (pain, function, footwear and general foot health) and MFPDI subscales (pain, functional limitation and concern about appearance) was determined using (i) paired t-tests, (ii) Cohen's d, (iii) the standardised response mean (SRM), and (iv) the Guyatt index. RESULTS Overall, the FHSQ pain subscale exhibited the highest responsiveness, as evidenced by a highly significant paired t-test (p <0.001), Cohen's d = 0.63 (medium effect size), SRM = 0.50 (medium effect size) and Guyatt index = 1.70 (huge effect size). The next most responsive measure was the FHSQ function subscale, as evidenced by a borderline paired t-test (p = 0.050), Cohen's d = 0.37 (small effect size), SRM = 0.26 (small effect size) and GI = 1.22 (very large effect size). The FHSQ footwear, FHSQ general foot health and MFPDI pain, functional limitation and concern about appearance subscales demonstrated lower responsiveness, with negligible to medium effect sizes. CONCLUSION The FHSQ pain and function subscales were most responsive to change in older people with foot pain receiving a footwear intervention. These findings provide useful information to guide researchers in selecting appropriate outcome measures for use in future clinical trials of foot disorders.