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?

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Sex Differences in the Effectiveness of First-Line Tumor Necrosis Factor Inhibitors in Psoriatic Arthritis: Results From the European Spondyloarthritis Research Collaboration Network.

OBJECTIVE: Women with psoriatic arthritis (PsA) may have reduced tumor necrosis factor inhibitor (TNFi) effectiveness compared to men. We examined sex differences in treatment response and retention rates during 24 months of follow-up among patients with PsA initiating their first TNFi. METHODS: Data from patients with PsA across 13 European Spondyloarthritis Research Collaboration Network registries starting their first TNFi were pooled. Logistic regression was used to analyze the association between sex and treatment response using low disease activity (LDA) according to the Disease Activity Score in 28 joints using the C-reactive protein level (DAS28-CRP) (<3.2) at six months as the primary outcome. Analyses were adjusted for age, country, conventional synthetic disease-modifying antirheumatic drug treatment, and TNFi start year. Retention rates were explored using the Kaplan-Meier estimator. RESULTS: We analyzed the treatment response of 7,679 patients with PsA (50% women) with available data on LDA at six months. At baseline, women and men had similar characteristics, including mean DAS28-CRP (women vs men, 4.4 [SD 1.2] vs 4.2 [SD 1.2]), though patient-reported outcome measures were worse in women. At six months, 64% of women and 78% of men had LDA (relative risk [RR] 0.82; 95% confidence interval [CI] 0.80-0.84). This difference was similar after adjustment (RR 0.83; 95% CI 0.81-0.85). TNFi retention rates were evaluated in 17,842 patients with PsA. Women had significantly lower retention rates than men at all time points (women 79%, 64%, and 50% vs men 88%, 77%, and 64% at 6, 12, and 24 months, respectively). CONCLUSION: Despite comparable disease characteristics at baseline, women with PsA have reduced treatment response and retention rates to their first TNFi, highlighting the need to consider sex differences in PsA research and management.

Commonalities and differences in set-up and data collection across European spondyloarthritis registries - results from the EuroSpA collaboration.

BACKGROUND: In European axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA) clinical registries, we aimed to investigate commonalities and differences in (1) set-up, clinical data collection; (2) data availability and completeness; and (3) wording, recall period, and scale used for selected patient-reported outcome measures (PROMs). METHODS: Data was obtained as part of the EuroSpA Research Collaboration Network and consisted of (1) an online survey and follow-up interview, (2) upload of real-world data, and (3) selected PROMs included in the online survey. RESULTS: Fifteen registries participated, contributing 33,948 patients (axSpA: 21,330 (63%), PsA: 12,618 (37%)). The reported coverage of eligible patients ranged from 0.5 to 100%. Information on age, sex, biological/targeted synthetic disease-modifying anti-rheumatic drug treatment, disease duration, and C-reactive protein was available in all registries with data completeness between 85% and 100%. All PROMs (Bath Ankylosing Spondylitis Disease Activity and Functional Indices, Health Assessment Questionnaire, and patient global, pain and fatigue assessments) were more complete after 2015 (68-86%) compared to prior (50-79%). Patient global, pain and fatigue assessments showed heterogeneity between registries in terms of wording, recall periods, and scale. CONCLUSION: Important heterogeneity in registry design and data collection across fifteen European axSpA and PsA registries was observed. Several core measures were widely available, and an increase in data completeness of PROMs in recent years was identified. This study might serve as a basis for examining how differences in data collection across registries may impact the results of collaborative research in the future.