Table 1.

Enrollment characteristics of African American rheumatoid arthritis cases and African American controls^*

Characteristic	Cases (n = 727)	Controls (n = 268)	P-value
Age, years	54.0 ± 12.9	52.4 ± 12.6	0.27
Female gender	608 (83.6%)	199 (74.3%)	0.001
Disease duration at baseline visit, years	6.0 ± 8.7
ACPA positive	474 (67.7%)	11 (4.6%)	<0.001
Rheumatoid factor (RF) positive	538 (75.7%)	37 (15.2%)	<0.001
Smoking status			0.23
Never	346 (47.7%)	141 (53.0%)
Former	180 (24.8%)	65 (24.4%)
Current	199 (27.5%)	60 (22.6%)
Cumulative smoking exposure			0.001
Never or < 10 pack-years	517 (72.0%)	217 (82.2%)
≥ 10 pack-years	201 (28.0%)	47 (17.8%)

^*ACPA = anti-citrullinated protein antibody; comparisons using chi-square test for categorical variables and two-sample t-test for continuous variables