Table 5.
Baseline characteristics of all participants without RA; ACPA-positive (≥6.2 U/mL) versus ACPA-negative
| All (n=39 298) | ACPA-positive participants (n=311) | ACPA-negative participants (n=38 987) | p Value | |
|---|---|---|---|---|
| Age (years) | 44 (34–51) | 46 (35–52) | 44 (34–51) | 0.017 |
| Gender (female) | 58% | 62% | 58% | 0.103 |
| BMI (kg/m2) | 25 (23–28) | 25 (23–28) | 25 (23–28) | 0.834 |
| Obesity | 15% | 13% | 15% | 0.444 |
| Smoking: pack years | 0 (0–8) | 1 (0–11) | 0 (0–8) | <0.001 |
| Smoking status | 0.006 | |||
| Never smoker | 49% | 40% | 49% | |
| Former smoker | 30% | 35% | 30% | |
| Current smoker | 21% | 25% | 21% | |
| Alcohol (g/day) | 3 (0–11) | 3 (0–9) | 3 (0–11) | 0.861 |
| Alcohol intake, categories | 0.499 | |||
| None to 5 g/day | 59% | 57% | 59% | |
| 5 g/day to <10 g/day | 16% | 18% | 16% | |
| 10 g/day or more | 25% | 24% | 25% | |
| Fish intake (servings/month) | 5 (2–9) | 5 (2–9) | 5 (2–9) | 0.754 |
| Sugar-sweetened soft drink intake (glasses/month) | 6 (0–22) | 6 (0–20) | 6 (0–22) | 0.270 |
| Periodontitis (self-reported) | 12% | 14% | 12% | 0.284 |
| Joint complaints: pain and/or stiffness in hands and/or feet | 20% | 26% | 20% | 0.018 |
| Joint complaints: both pain and stiffness in hands and/or feet | 11% | 15% | 11% | 0.026 |
| FDR with rheumatism | 14% | 15% | 14% | 0.476 |
| In women (n=22 727) | ||||
| Nulliparity | 27% | 28% | 27% | 0.926 |
| Menopausal status, categories | 0.145 | |||
| Premenopausal | 63% | 73% | 63% | |
| Postmenopausal and hormone use | 4% | 4% | 4% | |
| Postmenopausal and no hormone use | 33% | 23% | 34% | |
| Regular menses | 78% | 78% | 78% | 0.984 |
| Age of menarche ≤10 | 2% | 3% | 2% | 0.302 |
Data are presented as median (IQR) for continuous variables and percentages for categorical variables.
ACPA, anticitrullinated protein antibodies; BMI, body mass index; FDR, first-degree relative; RA, rheumatoid arthritis.