The association of race and ethnicity with disease expression in male US veterans with rheumatoid arthritis

Objective. To examine the association of race/ethnicity with measures of disease activity and severity among male US veterans with rheumatoid arthritis (RA). Methods. Measures of disease activity and severity were examined in a group of US veterans (n = 573) with RA, comparing measures in African American men (n = 79) with Caucasian men (n = 494). Dichotomous variables were compared using logistic regression while continuous variables were examined using linear regression, adjusting for the effects of age, disease duration, and smoking status. Results. Compared to Caucasians, African Americans were slightly younger (65.0 vs 67.1 yrs; p = 0.09) at enrollment and had a similar age at disease onset (50.5 vs 50.6 years; p = 0.98). After adjusting for age, disease duration, and smoking status, there were no differences based on race/ethnicity in rheumatoid factor positivity, the presence of radiographic changes, physical functioning, swollen joint counts, Disease Activity Score (DAS28), or global well-being scores. In contrast, African Americans were about 50% less likely than Caucasians with RA to have subcutaneous nodules (adjusted OR 0.51, 95% CI 0.30-0.86) and had lower tender joint counts (p = 0.007), associations that were attenuated and not significant with further adjustment for collection site. Conclusion. With the possible exception of lower rates of rheumatoid nodules and lower tender joint counts in African Americans, there is little evidence to support the existence of important racial/ethnic differences in RA disease expression between African American and Caucasian men.