Distinction of active ANCA-associated vasculitis (AAV) from remission or from healthy controls: receiver operating characteristic (ROC) analyses and likelihood ratios
| Active AAV versus remission | Active AAV versus controls | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Marker | AUC* | OCP† | Sensitivity‡ | Specificity‡ | LR+§ | AUC* | OCP† | Sensitivity‡ | Specificity‡ | LR+§ |
| BCA-1 | 0.86 | 70 | 77 (69–83) | 85 (78–90) | 5.13 | 0.91 | 70 | 75 (68–81) | 93 (84–98) | 10.7 |
| ESR | 0.76 | 23 | 68 (59–76) | 76 (68–83) | 2.83 | ND | ||||
| GM-CSF | 0.72 | 10 | 60 (51–68) | 82 (74–88) | 3.33 | 0.72 | 11 | 59 (52–66) | 81 (70–89) | 3.11 |
| IL-6 | 0.75 | 0.68 | 75 (67–82) | 71 (62–78) | 2.59 | 0.77 | 0.51 | 77 (70–83) | 78 (66–87) | 3.50 |
| IL-15 | 0.74 | 17 | 58 (50–67) | 82 (75–88) | 3.22 | 0.86 | 4.5 | 87 (81–92) | 78 (66–87) | 3.95 |
| IL-18BP | 0.74 | 93 | 54 (45–63) | 85 (78–91) | 3.60 | 0.73 | 22.5 | 73 (66–79) | 69 (57–80) | 2.35 |
| KIM-1 | 0.76 | 90 | 72 (64–80) | 69 (59–75) | 2.32 | 0.74 | 43 | 86 (80–91) | 63 (51–75) | 2.32 |
| MMP-3 | 0.89 | 38 | 82 (74–88) | 88 (81–93) | 6.83 | 0.94 | 29.5 | 87 (81–92) | 93 (84–98) | 12.4 |
| NGAL | 0.73 | 193 | 74 (66–81) | 64 (55–72) | 2.06 | 0.89 | 190 | 72 (65–78) | 91 (82–97) | 8.00 |
| NGFβ | 0.74 | 4.5 | 67 (58–74) | 77 (69–84) | 2.91 | 0.74 | 5.7 | 61 (53–68) | 82 (71–91) | 3.39 |
| TIMP-1 | 0.83 | 270 | 78 (70–85) | 82 (74–88) | 4.33 | 0.93 | 237 | 80 (73–85) | 93 (84–98) | 11.4 |
*AUC, area under the ROC curve. An AUC of 1 indicates perfect discrimination between groups; an AUC of 0.5 indicates no discrimination.
†OCP, optimal cut-off point, which is the maximum sum of sensitivity and specificity; for units, see table 1.
‡Sensitivity and specificity, at OCP, determined by values greater than OCP in active AAV and less than OCP in remission or controls unless otherwise noted. 95% confidence intervals (asymptotic method) are shown. ND, not done.
§LR+, positive likelihood ratio at the OCP, which equals sensitivity/(1−specificity).
BCA-1, CXCL13; ESR, erythrocyte sedimentation rate; GM-CSF, granulocyte–monocyte colony-stimulating factor; IL, interleukin; IL-18BP, interleukin 18 binding protein; KIM-1, kidney injury molecule-1; MMP-3, matrix metalloproteinase-3; NGAL, neutrophil gelatinase-associated lipocalin; NGFβ, nerve growth factor β; TIMP-1, tissue inhibitor of metalloproteinases-1.