Cut-Offs for Disease Activity States in Axial Spondyloarthritis With Ankylosing Spondylitis Disease Activity Score (ASDAS) Based on C-Reactive Protein and ASDAS Based on Erythrocyte Sedimentation Rate: Are They Interchangeable?

Ankylosing Spondylitis Disease Activity Score based on C-reactive protein (ASDAS-CRP) is recommended over ASDAS based on erythrocyte sedimentation rate (ASDAS-ESR) to assess disease activity in axial spondyloarthritis (axSpA). Although ASDAS-CRP and ASDAS-ESR are not interchangeable, the same disease activity cut-offs are used for both. We aimed to estimate optimal ASDAS-ESR values corresponding to the established ASDAS-CRP cut-offs (1.3, 2.1, and 3.5) and investigate the potential improvement of level of agreement between ASDAS-ESR and ASDAS-CRP disease activity states when applying these estimated cut-offs. We used data from patients with axSpA from 9 European registries initiating a tumor necrosis factor inhibitor. ASDAS-ESR cut-offs were estimated using the Youden index. The level of agreement between ASDAS-ESR and ASDAS-CRP disease activity states was compared against each other. In 3664 patients, mean ASDAS-CRP was higher than ASDAS-ESR at both baseline (3.6 and 3.4, respectively) and aggregated follow-up at 6, 12, or 24 months (1.9 and 1.8, respectively). The estimated ASDAS-ESR values corresponding to the established ASDAS-CRP cut-offs were 1.4, 1.9, and 3.3. By applying these cut-offs, the proportion of discordance between disease activity states according to ASDAS-ESR and ASDAS-CRP decreased from 22.93% to 19.81% in baseline data but increased from 27.17% to 28.94% in follow-up data. We estimated the optimal ASDAS-ESR values corresponding to the established ASDAS-CRP cut-off values. However, applying the estimated cut-offs did not increase the level of agreement between ASDAS-ESR and ASDAS-CRP disease activity states to a relevant degree. Our findings did not provide evidence to reject the established cut-off values for ASDAS-ESR.

Georgiadis S ，Ørnbjerg LM ，Michelsen B ，Kvien TK ，Di Giuseppe D ，Wallman JK ，Závada J ，Provan SA ，Kristianslund EK ，Rodrigues AM ，Santos MJ ，Rotar Ž ，Pirkmajer KP ，Nordström D ，Macfarlane GJ ，Jones GT ，van der Horst-Bruinsma I ，Hellamand P ，Østergaard M ，Hetland ML ... -  《-》

Is there any gender-specific difference in the cut-off values of ankylosing spondylitis disease activity score in patients with axial spondyloarthritis?

To assess the validity of Assessment in Spondyloarthritis International Society (ASAS) endorsed Ankylosing Spondylitis Disease Activity Score (ASDAS) C-reactive protein (-CRP) and ASDAS erythrocyte sedimentation rate (-ESR) in axial spondyloarthritis (axSpA) and to estimate the cut-off values for male and female patients with axSpA. Patients with axSpA were assessed for disease activity, functions, mobility and AS Quality of Life (ASQoL) and pain. The discriminant ability of ASDAS versions was assessed using standardized mean differences. Optimal cut-off values of ASDAS versions were calculated. Patients with axSpA were included (196 AS, 164 non-radiographic axSpA). ASDAS versions and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) had good correlations with patient's global (PtG) and physician's global (PhG) assessment in both groups; however, men had relatively higher coefficients. Women had significantly higher pain, ASQoL, ASDAS-ESR, BASDAI item scores, PtG, PhG and ESR. Discriminant abilities of ASDAS-CRP, ASDAS-ESR and BASDAI were similar in men and women regarding low and high disease activity. ASDAS cut-offs are quite similar in both genders and in accordance with predefined values. The cut-offs for ASDAS-ESR were relatively lower than ASDAS-CRP and women tend to have higher cut-offs than men. The construct validity of ASDAS-CRP to discriminate low and high disease activity and cut-off values are similar in male and female patients with axSpA; however, cut-offs for ASDAS-ESR need to be defined.

Kilic G ，Kilic E ，Ozgocmen S 《-》

Discriminant validity of the Ankylosing Spondylitis Disease Activity Score (ASDAS) in patients with non-radiographic axial spondyloarthritis and ankylosing spondylitis: a cohort study.

Kilic E ，Kilic G ，Akgul O ，Ozgocmen S ... -  《-》

The Discriminative Values of the Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, C-Reactive Protein, and Erythrocyte Sedimentation Rate in Spondyloarthritis-Related Axial Arthritis.

Tsang HHL ，Chung HY 《-》

Performance of the Ankylosing Spondylitis Disease Activity Score based on a quick quantitative C-reactive protein assay in patients with axial spondyloarthritis.

To evaluate the performance of the Ankylosing Spondylitis Disease Activity Score based on a validated quick quantitative C-reactive protein assay (ASDAS-qCRP) as compared to ASDAS based on a routine lab CRP assay (ASDAS-CRP) and ASDAS based on erythrocyte sedimentation rate (ASDAS-ESR). Disease activity assessment was performed in 50 patients with axial spondyloarthritis (axSpA). Routine lab CRP was measured in the central lab while the quantitative quick-CRP assay and ESR measurements were performed locally. ASDAS-CRP, ASDAS-qCRP and ASDAS-ESR were subsequently calculated. The mean (±SD) serum level of the routine lab CRP (6.2±8.3mg/l) was lower than of the quick-CRP (7.4±8.4mg/l) (P<0.05). Whereat, there was no significant difference in the mean values of ASDAS-CRP and ASDAS-qCRP in axSpA patients (2.70±0.94 and 2.74±0.96, respectively, P=0.069), while the ASDAS-ESR (2.85±1.0) was significantly higher than ASDAS-CRP (P=0.036) and numerically higher than ASDAS-qCRP (P=0.125). In 47 of the 50 cases of axSpA (94%), patients were assigned to the same disease activity category according to ASDAS-CRP and ASDAS-qCRP. ASDAS-qCRP performed similarly well compared to ASDAS-CRP with the absolute agreement on the disease activity category according to the ASDAS of 94%. ASDAS-qCRP is, therefore, feasible for an immediate decision-making in clinical practice and trials aimed at treating to target.

Proft F ，Muche B ，Spiller L ，Rios Rodriguez V ，Rademacher J ，Weber AK ，Lüders S ，Protopopov M ，Redeker I ，Spiller I ，Sieper J ，Poddubnyy D ... -  《-》