Relationship between MDA-5 and other indices of low disease activity. The established MDA criteria (MDA-5) serve as the reference, or “gold standard.” The performance of the other measures listed in column 1 is tested against this standard. The performance statistics are represented by sensitivity, specificity, overall accuracy, PPV, NPV, Youden index, and bias-adjusted κ statistic. Values are % unless otherwise specified.
| Variables | Sensitivity | Specificity | Overall Accuracy | PPV | NPV | Youden Index | κ* |
|---|---|---|---|---|---|---|---|
| MDA-joints | 70 | 100 | 93 | 100 | 92 | 70 | 0.86 |
| PASDAS | 83 | 87 | 86 | 68 | 94 | 70 | 0.73 |
| CPDAI-4 | 96 | 72 | 78 | 52 | 98 | 68 | 0.75 |
| CPDAI-3 | 91 | 86 | 87 | 68 | 97 | 77 | 0.75 |
↵* κ: prevalence adjusted, bias adjusted κ. MDA: minimal disease activity; MDA-5: MDA criteria with 5 items required; PPV: positive predictive value; NPV: negative predictive value; MDA-joints: MDA criteria mandating the articular items; PASDAS: Psoriatic Arthritis Disease Activity Score; CPDAI: Composite Psoriatic Disease Activity Index; CPDAI-4: CPDAI score with 4 as cutoff; CPDAI-3: CPDAI score with 3 as cutoff.