Table 2.
Relationship between HLA-DRB1 allele carrier status and rheumatoid factor status in French patients with early rheumatoid arthritis
| Carrier status | Odds ratio (95% confidence interval) | P | P for trend | ||
| Yes | No | ||||
| S1 carrier | |||||
| Rheumatoid factor-positive | 31 (55.4) | 79 (75.9) | 0.39 (0.19–0.83) | 0.0118 | 0.0051* |
| Rheumatoid factor-negative | 25 (44.6) | 25 (24.0) | |||
| S2 carrier | |||||
| Rheumatoid factor-positive | 49 (83.1) | 61 (60.4) | 3.21 (1.39–7.9) | 0.0028* | 0.0049* |
| Rheumatoid factor-negative | 10 (16.9) | 40 (39.6) | |||
| S3P carrier | |||||
| Rheumatoid factor-positive | 57 (74.0) | 53 (63.9) | 1.61 (0.78–3.38) | 0.1766 | 0.4478 |
| Rheumatoid factor-negative | 20 (26.0) | 30 (36.1) | |||
| S3D carrier | |||||
| Rheumatoid factor-positive | 19 (51.4) | 91 (74.0) | 0.37 (0.16–0.86) | 0.0145 | 0.0209 |
| Rheumatoid factor-negative | 18 (48.6) | 32 (26.0) | |||
Data presented as n (%). Status for rheumatoid factor among 160 patients with early rheumatoid arthritis, carrying the different HLA-DRB1 alleles encoding the shared epitope classified into four groups according to the new classification. Odds ratios, 95% alpha-risk confidence interval and P value for exact Fisher test. The dose effect was investigated for alleles positively or negatively associated with immunological markers using tests for trend of the log odds. *Significant after correcting for multiple testing according to the Benjamini–Yekutieli 2001 method at an overall critical P value of 5%.