HLA-DRB1* shared epitope (SE) association for 16 citrullinated peptides among patients with RA from the EIRA cohort
| Peptide | No SE Number not reacting/number reacting Raw data | Any SE Number not reacting/number reacting Raw data | OR (95% CI) Raw data | No SE Number not reacting/number reacting Arginine-subtracted data | Any SE Number not reacting/number reacting Arginine-subtracted data | OR (95% CI) Arginine-subtracted data |
| Fil307-324 (CCP1) | 542/201 | 1090/992 | 2.45 (2.04 to 2.95) | 536/207 | 1055/1027 | 2.52 (2.10 to 3.02) |
| Vim60-75 | 610/133 | 980/1102 | 5.16 (4.20 to 6.34) | 612/131 | 981/1101 | 5.24 (4.26 to 6.45) |
| Vim2-17 | 630/113 | 1318/764 | 3.23 (2.60 to 4.02) | 623/120 | 1291/791 | 3.18 (2.57 to 3.94) |
| Fibβ36–52 | 530/213 | 982/1100 | 2.79 (2.33 to 3.34) | 520/223 | 892/1190 | 3.11 (2.60 to 3.72) |
| Fibα563–583 | 586/157 | 1105/977 | 3.30 (2.71 to 4.01) | 577/166 | 1038/1044 | 3.50 (2.88 to 4.24) |
| Fibα580–600 | 668/75 | 1578/504 | 2.84 (2.20 to 3.69) | 668/75 | 1585/497 | 2.79 (2.16 to 3.62) |
| Fibα621–635 | 607/136 | 1295/787 | 2.71 (2.21 to 3.33) | 567/176 | 1127/955 | 2.73 (2.26 to 3.30) |
| Fibα36–50 | 636/107 | 1731/351 | 1.20 (0.95 to 1.52) | 634/109 | 1724/358 | 1.21 (0.96 to 1.52) |
| Fibβ60–74 | 510/233 | 680/1402 | 4.51 (3.77 to 5.40) | 511/232 | 683/1399 | 4.51 (3.77 to 5.40) |
| Eno5-21 (CEP-1) | 573/170 | 920/1162 | 4.26 (3.51 to 5.16) | 559/184 | 856/1226 | 4.35 (3.61 to 5.25) |
| Pept Z1 | 555/188 | 878/1204 | 4.05 (3.36 to 4.88) | 531/212 | 781/1301 | 4.17 (3.48 to 5.01) |
| Pept Z2 | 605/138 | 1202/880 | 3.21 (2.62 to 3.94) | 558/185 | 951/1131 | 3.59 (2.97 to 4.33) |
| Pept-1 | 619/124 | 1352/730 | 2.70 (2.18 to 3.33) | 600/143 | 1208/874 | 3.04 (2.48 to 3.72) |
| Pept-5 | 525/218 | 826/1256 | 3.66 (3.06 to 4.39) | 519/224 | 802/1280 | 3.70 (3.09 to 4.43) |
| Bla-26 | 607/136 | 1359/723 | 2.37 (1.93 to 2.92) | 608/135 | 1317/765 | 2.61 (2.13 to 3.22) |
| CII359-369 (citC1) | 702/41 | 1868/214 | 1.96 (1.39 to 2.77) | NA | NA | NA |
Data are shown both for raw data and for net data where the responses for the corresponding arginine-containing control peptides had been subtracted for each peptide (arginine-subtracted data). For each ACPA peptide, the OR version showing the strongest association is italicised and significant associations are depicted in bold letters. The reference groups are the patients not reacting with the investigated peptide in that comparison. For comparison, data have been included on the collagen peptide where no arginine subtraction has been made. Data are based on investigation of the 2825 RA patients with full anti-CCP2, HLA and smoking data, and the cut-offs were set at the 98% specificity level determined from 551 healthy controls.
ACPA, anticitrullinated protein/peptide antibodies; CCP2, cyclic citrullinated peptide 2; EIRA, Epidemiological Investigations in Rheumatoid Arthritis; NA, not applicable; RA, rheumatoid arthritis.