Background:
Foot pain is associated with obesity. Despite this association, change in foot pain following weight loss has been largely unexplored. This project aims to investigate i) if bariatric surgery reduces foot pain, ii) if baseline body composition predicts change in foot pain.
Methods:
This project was a repeated measures cohort study. Participants with foot pain were recruited from the waiting list of two tertiary hospitals. Measures were taken at baseline and six-month follow-up. Foot pain was assessed with the Manchester-Oxford Foot and Ankle Questionnaire. Body composition was analysed with dual-energy X-ray absorptiometry, from these data fat mass index (FMI) and fat-free mass index (FFMI) were calculated. Within-group changes were analysed with paired samples t-tests or the Wilcoxon signed-rank test. Multivariable linear regression was used to determine predictors of change in foot pain between baseline and follow-up.
Results:
Forty-five participants, 38 women and seven men, with a mean (SD) age of 45.7 (9.4) years were recruited for this study. Twenty-nine participants (BMI = 44.8 (7.0)kg) underwent bariatric surgery, while 16 (BMI = 47.9 (5.2)kg) remained on the waiting-list. Foot pain significantly reduced in the treatment group, from mean (SD) 54.3 (16.4) to 19.8 (18.9), while there was a non-significant change in those who remained on the waiting-list. In multivariable analysis, bariatric surgery was significantly associated with reduced pain at follow-up (B -32.6, 95% CI -43.8 to -21.4), while FMI (B 1.5, 95% CI 0.2 to 2.8), but not FFMI (B -1.4, 95% CI -3.4 to 0.5), was independently associated with increased pain at follow-up, after controlling for age, gender and depression.
Conclusions: Bariatric surgery is significantly associated with reduced foot pain. Higher baseline FMI, but not FFMI, was predictive of increased foot pain at follow-up. Foot pain may be mediated by metabolic, rather than mechanical, factors in bariatric surgery candidates.