Porphyromonas gingivalis serology is not an independent predictor of structural progression in the multivariate logistic regression results
| OR (95% CI) | P value | |
| Model 1 | ||
| Smoking status | 0.87 (0.64 to 1.26) | 0.359 |
| Age | 1.04 (1.02 to 1.05) | <0.001 |
| Gender | 0.75 (0.50 to 1.10) | 0.157 |
| P. gingivalis serology | 0.75 (0.47 to 1.21) | 0.235 |
| HLA-DRB1 genotype* | 1.46 (0.95 to 2.23) | 0.078 |
| Model 2 | ||
| Smoking status | 0.81 (0.59 to 1.11) | 0.197 |
| Age | 1.05 (1.03 to 1.07) | <0.001 |
| Gender | 0.74 (0.48 to 1.11) | 0.156 |
| P. gingivalis serology | 0.74 (0.46 to 1.22) | 0.231 |
| HLA-DRB1 genotype | 0.86 (0.53 to 1.40) | 0.550 |
| Alcohol intake | 1.16 (0.75 to 1.87) | 0.520 |
| Baseline DAS28 | 1.03 (0.86 to 1.23) | 0.756 |
| Rheumatoid factor | 1.14 (0.78 to 1.67) | 0.499 |
| ACPA | 2.26 (1.49 to 3.47) | <0.001 |
P. gingivalis antibodies were measured using a homemade ELISA as previously described.2 Patients were considered P. gingivalis positive when their anti-P. gingivalis antibody titre was above the higher quartile.
Radiological progression was defined as a progression ≥1 point/year of modified Sharp/van der Heijde score within the first 5 years of follow-up.
*Shared epitope alleles were HLA–DRB1 *0101, *0102, *0401, *0404, *0405, *0408, *0410, and *1001.3
ACPA, anticitrullinated protein antibody; DAS28, Disease Activity Score 28 joints; HLA, human leucocyte antigen.