Table 1.
Rate of anti‐CCP2 positivity among RA cases categorized by RF status, number of SE alleles, and smoking statusa
| No. of RA cases | Anti‐CCP2 positive, no. (%) | |
|---|---|---|
| RF‐negative | ||
| 0 alleles | ||
| Never smoker | 179 | 18 (10.1) |
| Ever smoker | 254 | 23 (9.1) |
| 1 allele | ||
| Never smoker | 209 | 59 (28.2) |
| Ever smoker | 317 | 104 (32.8) |
| 2 alleles | ||
| Never smoker | 73 | 38 (52.1) |
| Ever smoker | 111 | 60 (54.1) |
| RF‐positive | ||
| 0 alleles | ||
| Never smoker | 128 | 86 (67.2) |
| Ever smoker | 296 | 205 (69.3) |
| 1 allele | ||
| Never smoker | 313 | 265 (84.7) |
| Ever smoker | 808 | 701 (86.8) |
| 2 alleles | ||
| Never smoker | 192 | 177 (92.2) |
| Ever smoker | 496 | 473 (95.4) |
a
Anti‐CCP2 = anti–cyclic citrullinated peptide 2; RA = rheumatoid arthritis; RF = rheumatoid factor; SE = shared epitope.