The importance of the baseline Disease Activity Score 28 in determining responders and non-responders to anti-TNF in UK clinical practice

Abstract

The NICE re-appraisal of anti-TNF requires demonstration of ongoing response, making the baseline 28-joint Disease Activity Score (DAS28) crucially important. A retrospective analysis of all RA patients on their first anti-TNF determined predictive factors for those classified as non-responders at 6 months according to current NICE guidelines. The patients were divided into responders (DAS28 dropped by >1.2) and non-responders. These groups were compared for demographics, DAS28 at the two pre-assessments 1 month apart and at baseline. Exposure to intramuscular, oral and IA steroids in the 3 months period before the baseline DAS28 was recorded. At 6-month assessment in 256 patients, 82.8% were responders with no demographic differences between them and non-responders. Although the first pre-assessment score was not significantly different (6.8 vs 6.6), the second pre-assessment score (7.1 vs 6.7) and the baseline DAS (7.2 vs 6.3) were lower in the non-responders (P < 0.04 and P < 0.001, respectively). Comparing the differences in DAS28 from the first pre-assessment to baseline, the responders had increased by 0.4, and the non-responders had decreased by 0.4, (P < 0.001). If the first pre-assessment score had been taken as the baseline DAS28, then 9.4% of responders would be re-classified as non-responders, and 31.8% of non-responders would be re-classified as responders. The proportion of patients who had steroid treatment within the 3 months period before the baseline DAS28 did not differ significantly between the responders and non-responders (34% vs 41%, P = 0.38). Baseline DAS28 is critical in classifying responders at the 6-month assessment.