Table 1.
Baseline sociodemographic and clinical characteristics of cross-sectional study participants, stratified by combinations of RF and ACPA seropositivity
| Overall | RF−/ACPA− | RF+/ACPA−or RF−/ACPA+ | RF+/ACPA+ | |
|---|---|---|---|---|
|
N |
2,328 | 341 | 384 | 1,603 |
| Age, median (IQR) |
64 (58–71) | 65 (59–73) | 63 (56–70) | 64 (58–71) |
| Male, n (%) |
2,065 (89.3) | 298 (87.9) | 326 (85.6) | 1,441 (90.5) |
| Race, n (%) | ||||
| American Indian or Alaska Native | 18 (0.8) | 3 (0.9) | 4 (1.0) | 11 (0.7) |
| Asian | 7 (0.3) | 2 (0.6) | 1 (0.3) | 4 (0.2) |
| Black or African American | 345 (14.8) | 40 (11.7) | 67 (17.4) | 238 (14.9) |
| Multiracial | 18 (0.8) | 5 (1.5) | 1 (0.3) | 12 (0.7) |
| Native Hawaiian or Pacific Islander | 10 (0.4) | 1 (0.3) | 2 (0.5) | 7 (0.4) |
| White | 1,775 (76.3) | 274 (80.4) | 282 (73.4) | 1,219 (76.1) |
| Missing | 153 (6.6) | 16 (4.7) | 27 (7.0) | 110 (6.9) |
| Ethnicity, n (%) |
||||
| Hispanic or Latino | 100 (4.3) | 11 (3.2) | 20 (5.2) | 69 (4.3) |
| Not Hispanic or Latino | 2,140 (92.0) | 322 (94.4) | 346 (90.1) | 1,472 (91.9) |
| Missing | 86 (3.7) | 8 (2.3) | 18 (4.7) | 60 (3.7) |
| BMI, median (IQR) |
28.1 (24.8–32.0) | 28.5 (25.5–32.4) | 27.8 (24.9–32.0) | 28.1 (24.8–31.9) |
| Smoking history, n (%) |
||||
| Never | 478 (21.0) | 93 (27.7) | 104 (27.9) | 281 (17.9) |
| Former | 572 (25.1) | 61 (18.2) | 68 (18.2) | 443 (28.2) |
| Current | 1,231 (54.0) | 182 (54.2) | 201 (53.9) | 848 (53.9) |
| RA disease duration, years, median (IQR) |
8.0 (2.4–17.5) | 5.9 (1.9–12.9) | 7.0 (2.2–15.4) | 8.8 (2.8–19.0) |
| DAS28, median (IQR) |
3.6 (2.5–5.1) | 3.5 (2.5–5.0) | 3.3 (2.3–4.6) | 3.7 (2.5–5.2) |
| MDHAQ, median (IQR) |
0.9 (0.4–1.3) | 0.9 (0.4–1.3) | 0.7 (0.3–1.2) | 0.9 (0.4–1.3) |
| Prednisone use (%) |
1,133 (48.7) | 150 (44.0) | 192 (50.1) | 791 (49.3) |
| Methotrexate use (%) |
1,301 (55.9) | 175 (51.3) | 216 (56.4) | 910 (56.8) |
| Anti-TNF use (%) | 659 (28.3) | 75 (22.0) | 103 (26.9) | 481 (30.0) |
Definition of abbreviations: ACPA = anti–citrullinated protein antibody; BMI = body mass index; DAS28 = Disease Activity Score in 28 Joints; IQR = interquartile range; MDHAQ = Multidimensional Health Assessment Questionnaire; RA = rheumatoid arthritis; RF = rheumatoid factor; TNF = tumor necrosis factor.