Foot osteoarthritis frequency and associated factors in a community-based cross-sectional study of White and African American adults.

OBJECTIVE Few studies have explored foot osteoarthritis (OA) in the general population. The purpose of this study was to determine the frequency of foot OA and identify associated factors in a cross-sectional analysis of a large community-based cohort. METHODS Data were from the 2013-2015 study visit of the Johnston County OA Project. Radiographic OA (rOA) of the foot was defined using the La Trobe radiographic atlas (≥2 osteophytes or joint space narrowing in at least one of five joints). Symptomatic OA (sxOA) of the foot was defined as foot rOA with pain, aching, or stiffness in the same foot. At the foot-level, separate logistic regression models with generalized estimating equations to account for intra-person correlations were performed to examine associations of foot rOA or sxOA with age, body mass index (BMI), sex, race, educational attainment, and previous foot injury. RESULTS Of 864 participants with available data (mean age 71 years, mean BMI 30 kg/m2 , 68% women, 33% African American, 13% <12 years of schooling), 22% had foot rOA, 20% had foot symptoms, and 5% had foot sxOA. Radiographic, but not symptomatic, foot OA was more common in African Americans than Whites. Participants with obesity, compared to normal weight, had over 2 times the odds of rOA and over 5 times the odds of sxOA in adjusted models. CONCLUSION Foot rOA and foot symptoms were common in the sample, but both conditions simultaneously (i.e., sxOA) occurred infrequently. Notably, obesity was linked with foot sxOA, perhaps implicating metabolic or mechanical influences.