OP0248 Potential differences in axial spondyloarthritis disease activity categorization using different minimum values for high-sensitivity crp in ankylosing spondylitis disease activity score calculation and different definitions of disease flare
Authors: R. Landewé, J. Sieper, U. Kiltz, X. Wang, M. Li, J. Anderson
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> It has been recommended that the lower limit of high-sensitivity CRP (hsCRP) be restricted to 2 in the Ankylosing Spondylitis Disease Activity Score (ASDAS) calculation. Also, a definition of flare of ASDAS increase ≥0.9 was recently proposed. <h3>Objectives</h3> Using non-radiographic axial SpA (nr-axSpA) trial data, this analysis evaluated potential differences in patient (pt) categorization using different minimum values for hsCRP in the ASDAS calculation and different definitions of disease flare. <h3>Methods</h3> ABILITY-3 (NCT01808118) assessed the impact of continuation versus withdrawal of adalimumab (ADA) in nr-axSpA pts who achieved sustained remission with open-label ADA. All pts received open-label ADA 40 mg every other wk during a 28-wk lead-in period. Pts who achieved remission, defined as ASDAS inactive disease (ID, ASDAS &lt;1.3) at wks 16, 20, 24, and 28 were randomised to 40-wk, double-blind ADA (continuation) or PBO (withdrawal). ASDAS was calculated with the full range of hsCRP (protocol-defined) and limiting hsCRP to the lowest possible value of 2 mg/L (rederived). Flare was calculated as 2 consecutive study visits with ASDAS &gt;2.1 (protocol definition) or with ASDAS increase ≥0.9 (modified definition). Data are reported as observed (open label) and by nonresponder imputation (double blind). <h3>Results</h3> 673 pts were enrolled. At open-label baseline, mean ASDAS using the protocol-defined ASDAS calculation was 3.6 vs 3.7 when rederived. At wk 28, 295 (43.8%) pts achieved protocol-defined ASDAS ID vs 272 (40.4%) pts using the rederived ASDAS; mean ASDAS at double-blind baseline was 0.7 vs 0.9, respectively. At wk 68, significantly more pts treated with ADA vs PBO had no flare per protocol definition (69.7% vs 47.1%; p&lt;0.001; table 1). Similar results were observed with modified definitions (table 1). At wk 68, significantly greater proportions of ADA vs PBO pts achieved ASDAS endpoints (all p&lt;0.001), with similar results for protocol-defined and rederived ASDAS calculations, respectively: ID (57.2% vs 33.3% and 52.0% vs 29.4%), major improvement (58.6% vs 32.0% and 50.0% vs 30.7%), and clinically important improvement (67.1% vs 45.1% and 67.1% vs 44.4%). <h3>Conclusions</h3> At both open-label and double-blind baseline, mean ASDAS was similar, regardless of the hsCRP value cut-off used. Fewer pts in both treatment groups were categorised as not experiencing a flare when limiting the lowest possible hsCRP value to 2 mg/L in the ASDAS calculation and/or using a modified flare definition. However, treatment differences remained similar compared with the protocol-defined methodology. Results suggest infrequent clinically relevant differences in ASDAS values with use of either definition for minimum hsCRP and that the use of ASDAS &gt;2.1 or ASDAS increase ≥0.9 as the definition of flare is reasonable. <h3>Acknowledgements</h3> AbbVie funded the study and approved the abstract for submission. Medical writing support was provided by Maria Hovenden, PhD, and Janet E. Matsuura, PhD, of Complete Publication Solutions, LLC (North Wales, PA) and was funded by AbbVie. <h3>Disclosure of Interest</h3> R. Landewé Grant/research support from: Abbott, Amgen, Centocor, Novartis, Pfizer, Roche, Schering-Plough, UCB, and Wyeth, Consultant for: consulting or advisory board fees from Abbott/AbbVie, Ablynx, Amgen, Astra-Zeneca, Bristol Myers Squibb, Celgene, Janssen (formerly Centocor), Galapagos, GlaxoSmithKline, Novartis, Novo-Nordisk, Merck, Pfizer, Roche, Schering-Plough, TiGenix, UCB, and Wyeth, Speakers bureau: Abbott/AbbVie, Amgen, Bristol Myers Squibb, Janssen (formerly Centocor), Merck, Pfizer, Roche, Schering-Plough, UCB, and Wyeth., J. Sieper Grant/research support from: from AbbVie, Janssen, Lilly, Merck, Novartis, Pfizer, Roche, and UCB., Consultant for: from AbbVie, Janssen, Lilly, Merck, Novartis, Pfizer, Roche, and UCB., Speakers bureau: from AbbVie, Janssen, Lilly, Merck, Novartis, Pfizer, Roche, and UCB., U. Kiltz Grant/research support from: from AbbVie, Chugai, Grünenthal, MSD, Novartis, Pfizer, Roche and UCB., Consultant for: from AbbVie, Chugai, Grünenthal, MSD, Novartis, Pfizer, Roche and UCB., X. Wang Shareholder of: AbbVie, Employee of: AbbVie, M. Li Shareholder of: AbbVie, Employee of: AbbVie, J. Anderson Shareholder of: AbbVie, Employee of: AbbVie