Combination of an IgM RF test and an IgA RF test
| Patients with RA No (%) | Non-RA controls No (%) | Likelihood ratio | 95% Confidence interval | |
|---|---|---|---|---|
| Sigma IgM RF + Inova IgA RF | ||||
| Both negative | 26 (17.8) | 58 (77.3) | 0.23 | 0.16 to 0.33 |
| Discrepant | 32 (21.9) | 11 (14.7) | 1.49 | 0.82 to 2.80 |
| Both positive | 88 (60.3) | 6 (8.0) | 7.5 | 3.6 to 16.4 |
| Diamedix IgM RF + Inova IgA RF | ||||
| Both negative | 16 (11.0) | 48 (64.0) | 0.17 | 0.10 to 0.28 |
| Discrepant | 37 (25.3) | 20 (26.7) | 0.95 | 0.60 to 1.53 |
| Both positive | 93 (63.7) | 7 (9.3) | 6.8 | 3.5 to 14.0 |
| IgM RF (our laboratory) + Inova IgA RF | ||||
| Both negative | 25 (17.1) | 51 (68.0) | 0.25 | 0.17 to 0.37 |
| Discrepant | 32 (21.9) | 20 (26.7) | 0.82 | 0.51 to 1.34 |
| Both positive | 89 (61.0) | 4 (5.3) | 11.4 | 4.7 to 29.3 |