Absolute results of the DAS28-based flare criteria on fulfilling the five hypotheses regarding construct and criterion validity
| Criterion validity: databases 1 and 2 | Construct validity: database 3 | ||||||
|---|---|---|---|---|---|---|---|
| Flare criteria | Hypothesis 1 | Hypothesis 2 | Hypothesis 3 | Hypothesis 4 | Hypothesis 5 | ||
| In patients classified as a having a flare: | Sens/spec patient > 70% compared with transition scale | Sens/spec physician > 70% compared with transition scale | Higher proportion of DMARD/corticosteroid change (> 0.2) | Larger change in CRP (>10 mg/l) | No change in depression (≤ 5 points in MH scale) | ||
| Sens* % | Spec* % | Sens* % | Spec* % | Proportion difference† | CRP difference mg/l (SE)‡ | MH difference (SE)‡ | |
| 1) ΔDAS28 > 1.2, or > 0.6 if DAS28 > 5.1 | 46/56 | 95/92 | 53/78 | 95/92 | 0.28 | 13.1 (2.2) | −6.1 (1.4) |
| 2) ΔDAS28 > 1.2, or > 0.6 if DAS28 ≥ 3.2 | 69/63 | 92/84 | 73/78 | 92/86 | 0.23 | 11.4 (1.7) | −5.0 (1.2) |
| 3) ΔDAS28 > 0.6 or a DAS28 > 3.2 | 98/94 | 70/61 | 100/89 | 67/60 | 0.16 | 3.7 (1.2) | −2.8 (1.0) |
| 4) ΔDAS28 > 1.2 | 46/56 | 96/93 | 51/78 | 95/92 | 0.27 | 13.0 (2.3) | −6.6 (1.4) |
| 5) Reaching DAS28 > 3.2 | 91/88 | 78/67 | 91/89 | 76/68 | 0.18 | 3.1 (1.2) | −2.6 (1.0) |
| 6) Reaching DAS28 > 2.6 | 98/94 | 55/46 | 100/89 | 53/47 | 0.13 | 2.4 (1.0) | −3.2 (1.1) |
*Sens, sensitivity; Spec, specificity. Results from database 1/database 2 are represented on sensitivity and specificity.
†All proportion differences were tested with χ² analyses and statistically significant with p<0.0001.
‡All differences in CRP and MH scale were tested by means of a paired Student t test. Differences in CRP were all statistically significant, with at least p<0.05.
DAS28, Disease Activity Score 28; MH, mental health.