Predictive value of anti-citrullinated protein antibody (ACPA) isotypes for 10-year radiographic progression in the European Research on Incapacitating Disease and Social Support (EURIDISS) project
| Minor progression*, n (%) (n=62) | Major progression*, n (%) (n=63) | Positive likelihood ratio | Negative likelihood ratio | Odds ratio (95% CI) | p Value | Adjusted odds ratio (95% CI)† | Adjusted p value† | |
|---|---|---|---|---|---|---|---|---|
| ACPA positive | 22 (36) | 52 (83) | 2.31 | 0.27 | 8.60 (3.7 to 19.8) | <0.01 | 4.63 (1.7 to 12.6) | <0.01 |
| Analysis within ACPA-positive patients (n) | 22 | 52 | ||||||
| IgA ACPA positive | 12 (55) | 42 (81) | 1.47 | 0.42 | 3.50 (1.2 to 10.4) | 0.02 | 5.28 (1.2 to 22.6) | 0.03 |
| IgM ACPA positive | 5 (23) | 24 (46) | 2.00 | 0.70 | 2.91 (0.9 to 9.1) | 0.07 | 4.32 (1.1 to 16.9) | 0.04 |
| IgG1 ACPA positive‡ | 21 (96) | 52 (100) | 1.04 | 0.00 | – | – | – | – |
| IgG2 ACPA positive | 7 (32) | 31 (60) | 1.88 | 0.59 | 3.16 (1.1 to 9.1) | 0.03 | 5.81 (1.5 to 22.8) | 0.01 |
| IgG3 ACPA positive | 13 (59) | 40 (77) | 1.31 | 0.56 | 2.31 (0.8 to 6.7) | 0.13 | 3.48 (0.9 to 13.3) | 0.07 |
| IgG4 ACPA positive | 17 (77) | 44 (85) | 1.10 | 0.65 | 1.62 (0.5 to 5.6) | 0.45 | 1.62 (0.4 to 6.5) | 0.49 |
| Number of ACPA isotypes (median, IQR) | 3.0 (2.0–5.3) | 5.0 (3.3–6.0) | – | – | 1.41 (1.1 to 1.9) | 0.02 | 1.62 (1.1 to 2.4) | 0.01 |
| Five or more ACPA isotypes | 6 (27) | 29 (56) | 2.07 | 0.60 | 3.36 (1.1 to 9.9) | 0.03 | 6.76 (1.6 to 28.7) | 0.01 |
↵* Patients with a change in Sharp–van der Heijde score (SHS)greater than or equal to the median were classified as having major progression, while the other patients were classified as having minor progression.
↵† Multivariate logistic regression with adjustment for age, gender, C-reactive protein, IgM rheumatoid factor and SHS at baseline.
↵‡ Logistic regression analysis could not be performed to investigate the effect of IgG1 ACPA, because 100% of patients in the major progression group were positive for this isotype.