First evaluation of immunoassays: sensitivity in patients with rheumatoid arthritis (RA) (many of whom were latex negative) and specificity in non-RA control patients (many of whom were latex positive)
| Test | Origin of assay | Antigen (as presented by the manufacturers) | Sensitivity (95% confidence interval) | Specificity (95% confidence interval) | Agreement (%) |
|---|---|---|---|---|---|
| Positive patients were 67 patients with RA and negative patients were 91 patients with various other rheumatological or non-rheumatological diseases. | |||||
| Latex test | Our laboratory | Human Ig | 0.39 (0.27 to 0.51) | 0.68 (0.59 to 0.78) | 56 |
| IgM, IgG, and IgA RFs | Immco | Rabbit IgG | 0.66 (0.54 to 0.77) | 0.47 (0.37 to 0.58) | 55 |
| IgM RF | Immco | Rabbit IgG | 0.60 (0.48 to 0.72) | 0.35 (0.25 to 0.45) | 46 |
| IgM RF | Sigma | Inactivated affinity purified human IgG | 0.52 (0.40 to 0.64) | 0.64 (0.54 to 0.74) | 59 |
| IgM RF | Diamedix | Purified human IgG | 0.66 (0.54 to 0.77) | 0.46 (0.36 to 0.57) | 54 |
| IgM RF | Inova | Rabbit IgG | 0.42 (0.30 to 0.54) | 0.65 (0.55 to 0.75) | 55 |
| IgM RF | Our laboratory | Affinity purified human IgG Fc fragment | 0.49 (0.37 to 0.61) | 0.54 (0.44 to 0.64) | 52 |
| IgM RF | Our laboratory | Affinity purified rabbit IgG Fc fragment | 0.46 (0.34 to 0.58) | 0.59 (0.49 to 0.70) | 54 |
| IgA RF | Immco | Rabbit IgG | 0.19 (0.10 to 0.29) | 0.96 (0.91 to 1.00) | 63 |
| IgA RF | Inova | Rabbit IgG | 0.34 (0.23 to 0.46) | 0.86 (0.79 to 0.93) | 64 |
| IgA RF | Our laboratory | Affinity purified human IgG Fc fragment | 0.21 (0.11 to 0.31) | 0.90 (0.84 to 0.96) | 61 |
| IgA RF | Our laboratory | Affinity purified rabbit IgG Fc fragment | 0.09 (0.02 to 0.16) | 0.93 (0.88 to 0.99) | 58 |