Second evaluation of immunoassays: sensitivity in a group of non-selected patients with rheumatoid arthritis (RA) and specificity in non-RA controls
| Test | Origin of assay | Antigen (as presented by the manufacturers) | Sensitivity (95% confidence interval) | Specificity (95% confidence interval) | Agreement (%) |
|---|---|---|---|---|---|
| Positive patients were 146 patients with RA and negative patients were 75 patients with various other rheumatological diseases. | |||||
| Latex test | Our laboratory | Human Ig | 0.72 (0.65 to 0.79) | 0.87 (0.79 to 0.94) | 77 |
| IgM, IgG, and IgA RFs | Immco | Rabbit IgG | 0.86 (0.80 to 0.91) | 0.48 (0.37 to 0.59) | 73 |
| IgM RF | Sigma | Inactivated affinity purified human IgG | 0.77 (0.71 to 0.84) | 0.81 (0.72 to 0.90) | 79 |
| IgM RF | Diamedix | Purified human IgG | 0.88 (0.82 to 0.93) | 0.67 (0.56 to 0.78) | 81 |
| IgM RF | Our laboratory | Affinity purified human IgG Fc fragment | 0.79 (0.72 to 0.86) | 0.75 (0.65 to 0.85) | 77 |
| IgA RF | Inova | Rabbit IgG | 0.65 (0.57 to 0.73) | 0.88 (0.81 to 0.95) | 73 |
| IgA RF | Our laboratory | Affinity purified human IgG Fc fragment | 0.45 (0.36 to 0.53) | 0.91 (0.84 to 0.97) | 60 |