Foot function in rheumatoid arthritis patients: a cross-sectional study

Rheumatoid arthritis (RA) is a chronic disease that affects mainly small joints from hands and feet. The aims of this study were to analyze the prevalence of foot involvement in a sample of Brazilian RA patients and to explore the influence of disease variables such as inflammatory activity, serological, and epidemiological profile in this type of involvement. One hundred RA patients and 100 healthy controls paired for gender, age, and body mass index answered the FFI-BR (Foot Functional Index–Brazilian version) that evaluates foot function. RA patients had epidemiological and clinical data collection upon direct questioning and chart review. C-reactive protein (CRP), ESR (erythrocyte sedimentation rate), and DAS28-ESR were used to measure disease activity. In the RA sample, 98% had foot pain versus 76% in the controls (p < 0.0001; OR = 15.4; 95% CI = 3.4–67.5); 96% had some difficulty in function versus 66% of controls (p < 0.0001; OR = 12.3; 95% CI = 4.1–36.5); and 73% had some incapacity versus 20% of controls (p < 0.0001; OR = 10.8; 95% CI = 5.5–20.9). Values of FFI-BR showed correlation with ESR (p = 0.006), CRP (p = 0.01), and DAS28-ESR (p < 0.0001). No association between FFI-BR total score and gender, ethnic background, positive rheumatoid factor, tobacco exposure, and any of used medications was found (all p = ns). The majority of RA patients suffers from foot problems and was associated with inflammatory biomarkers. The control of inflammatory activity may help in the treatment of this problem.