Demographic characteristics of study populations
| Characteristics | Controls | RA |
| Number of subjects | 83 | 92 |
| Percentage of femalesa | 86.7% | 80.4% |
| Age (mean ± SD years)a | 46.1 ± 12.8 | 48.6 ± 11.6 |
| Ethnicity a | ||
| African American | 72.3% | 71.7% |
| White | 21.7% | 15.2% |
| Hispanic | 2.4% | 10.9% |
| Asian | 3.6% | 2.2% |
| Characteristics | Controls | RA |
| Number of subjects | 83 | 92 |
| Percentage of femalesa | 86.7% | 80.4% |
| Age (mean ± SD years)a | 46.1 ± 12.8 | 48.6 ± 11.6 |
| Ethnicity a | ||
| African American | 72.3% | 71.7% |
| White | 21.7% | 15.2% |
| Hispanic | 2.4% | 10.9% |
| Asian | 3.6% | 2.2% |
No significant difference.