Diagnostic sensitivity and specificity of anti-Sa, ACPA2, and RF combination assays using optimal cutoff values. All data are percentages.
| ACPA2 + Sa | Sa + RF | RF + CCP2 | |
|---|---|---|---|
| Sensitivity | 50 | 42.93 | 80.30 |
| Specificity | 99.42 | 98.84 | 95.93 |
| PPV | 99 | 97.70 | 97.55 |
| NPV | 63.33 | 60.07 | 81.16 |
ACPA2: anticitrullinated protein antibodies, second generation; RF: rheumatoid factor; PPV/NPV: positive/negative predictive value.