Construct and criterion validity of several proposed DAS28-based rheumatoid arthritis flare criteria: An OMERACT cohort validation study

Background: To describe rheumatoid arthritis (RA) worsening that leads to change or re-initiation of treatment, several Disease Activity Score 28 (DAS28)-based flare criteria have been described, but none validated. Methods: Six previously published DAS28-based flare criteria ((1) increase in DAS28 >1.2, or >0.6 if DAS28 >5.1; (2) increase in DAS28 >1.2, or >0.6 if DAS28 ≥3.2; (3) increase >0.6 or DAS28 >3.2; (4) increase in DAS28 >1.2; (5) DAS28 >3.2; (6) DAS28 >2.6) were tested against five hypotheses concerning criterion and construct validity: (1+2) Sensitivity and specificity >70% compared with patient's/physician's judgment; (3) difference in proportion with disease modifying anti-rheumatic drug/corticosteroid initiation/increase >0.2; (4) mean difference in C-reactive protein (CRP) >10 mg/l; and (5) no statistical difference in Short Form-36 Mental Health subscale change. Three different RA patient databases in which flare might occur were used. Sensitivity/specificity, Χ2and two-sample student t test analyses were done. Results: The analyses included 51, 147 and 744 RA patients, from the three databases. Criterion 2 fulfilled most hypotheses: 4 out of 5. Sensitivity and specificity varied between 63%-78% and 84%-92%. Construct validity was demonstrated with 23% more treatment change, higher mean CRP (11.4 mg/l) and depression scale change of -5. Criteria 3, 5 and 6 were more sensitive, criteria 1, 2 and 4 more specific. Conclusions: An increase in DAS28 >1.2 or >0.6 if DAS28 ≥3.2 appears most discriminating and valid by our predefined validation criteria. Considering the other criteria, sensitivity and specificity shown here might facilitate use in different settings. Copyright Article author (or their employer) 2012.

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