Associations Between Body Mass Index and Foot Joint Pain in Middle-Aged and Older Women: A Longitudinal Population-Based Cohort Study

OBJECTIVE To investigate the relationship between body mass index (BMI) and foot joint pain (FJP) over a 5-year period in a community-based cohort. METHODS We examined a subset of women from the Chingford Women's Study, a community cohort followed up for 20 years. From a baseline of 1,003 female participants, we reviewed data from 639 women (64%) for whom complete data sets for FJP and BMI were obtained over a 5-year period between year 10 (Y10) and year 15 (Y15). Descriptive statistics, binary regression modeling, and odds ratios (ORs) were used to examine the longitudinal relationship between BMI and FJP. RESULTS For Y10 and Y15, the median age was 61 years (interquartile range [IQR] 57-67) and 66 years (IQR 62-72), respectively, and the mean ± SD BMI was 26.7 ± 4.6 kg/m(2) and 27.2 ± 4.8 kg/m(2) , respectively. FJP prevalence was 21.6% at Y10 and 26.6% at Y15. Longitudinal analyses showed that both BMI and FJP increased significantly from Y10 to Y15 (P < 0.001). The odds of having FJP after a 5-year period increased by 4.9% for each BMI unit increase 5 years earlier (OR 1.049 [95% confidence interval (95% CI) 1.011-1.089], P = 0.012). This remained significant when adjusted for age, diabetes mellitus, and rheumatoid arthritis (OR 1.051 [95% CI 1.011-1.091], P = 0.012). CONCLUSION This is the first large longitudinal cohort study demonstrating that, in middle-aged women, a high BMI precedes and is predictive of FJP independent of age. Evidence from our findings can be used to identify those individuals at risk of developing FJP.