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ObjectivesTo estimate the relationship between EQ5D (three levels, UK version) and the Ankylosing Spondylitis Disease Activity Score (ASDAS) for use in the economic evaluation of health technologies for people with axial spondyloarthritis (axSpA). To compare against the relationship with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI).MethodsAn electronic, prospective, Portuguese, nationwide, rheumatic disease register (Reuma.pt) provided data on 1140 patients (5483 observations) with a confirmed diagnosis of axSpA. We estimated models of EQ5D as a function of ASDAS, alone or in combination with measures of functional impairment, using bespoke mixture models which reflect the complex distributional features of EQ5D. The SPondyloArthritis Caught Early cohort provided data from 344 patients (1405 observations) in four European countries and was used for validation. A previously published model of BASDAI/Bath Ankylosing Spondylitis Functional Index (BASFI) was also used to generate predicted EQ5D scores and model performance compared.ResultsA non-linear relationship exists between EQ5D from ASDAS. The final model included ASDAS, ASDAS squared, age and age squared and demonstrated close fit in both datasets except where data were sparse for patients with very high levels of disease activity (ASDAS >4). This finding held in the validation dataset. Models that included BASFI improved model fit. The ASDAS based models fit the data marginally less well than models using BASDAI.ConclusionsMapping models linking ASDAS to EQ5D allow results from clinical studies to be used in economic evaluation of health technologies with confidence. There is some loss of information compared with BASDAI but this has only a marginal impact.

Objective.To compare the association between different remission criteria and physical function in patients with rheumatoid arthritis followed in clinical practice.Methods.Longitudinal data from the METEOR database were used. Seventeen definitions of remission were tested: American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) Boolean-based; Simplified/Clinical Disease Activity Index (SDAI/CDAI); and 14 Disease Activity Score (DAS)-based definitions. Health Assessment Questionnaire (HAQ) ≤ 0.5 was defined as good functional status. Associations were investigated using generalized estimating equations. Potential confounders were tested and sensitivity analyses performed.Results.Data from 32,915 patients (157,899 visits) were available. The most stringent definition of remission was the ACR/EULAR Boolean-based definition (1.9%). The proportion of patients with HAQ ≤ 0.5 was higher for the most stringent definitions, although it never reached 100%. However, this also meant that, for the most stringent criteria, many patients in nonremission had HAQ ≤ 0.5. All remission definitions were associated with better function, with the strongest degree of association observed for the SDAI (adjusted OR 3.36, 95% CI 3.01–3.74).Conclusion.The 17 definitions of remission confirmed their validity against physical function in a large international clinical practice setting. Achievement of remission according to any of the indices may be more important than the use of a specific index. A multidimensional approach, targeted at wider goals than disease control, is necessary to help all patients achieve the best possible functional status.

ObjectivesTo investigate the occurrence of sick leave (SL) and the impact of clinical and socioeconomic factors on SL in early axial spondyloarthritis (axSpA).MethodsPatients with a clinical diagnosis of axSpA from the DEvenir des Spondyloarthrites Indifférenciées Récentes (DESIR) cohort with work-related data and up to 5-year follow-up were studied. Incidence, time to first SL and potential role of baseline and time-varying clinical and socioeconomic factors (age, gender, ethnicity, education, job type, marital and parental status) were analysed. Univariable analyses, followed by collinearity and interaction tests, guided subsequent multivariable time-varying Cox survival model building.ResultsIn total, 704 axSpA patients were included (mean (SD) age 33.8 (8.6); 46% men). At baseline, 80% of patients were employed; of these, 5.7% reported being on SL. The incidence of SL among those at risk during the study period (n=620, 88%) was 0.05 (95% CI 0.03 to 0.06) per 1000 days of follow-up. Mean (SD) time to first SL was 806 (595) days (range: 175–2021 days). In multivariable models, male gender (HR 0.41 (95% CI 0.20 to 0.86)) and higher education (HR 0.48 (95% CI 0.24 to 0.95)) were associated with lower hazard of SL, while higher disease activity (HR 1.49 (95% CI 1.04 to 2.13)), older age, smoking and use of tumour necrosis factor inhibitors were associated with higher hazard of SL.ConclusionsIn this early axSpA cohort of young, working-age individuals, male gender and higher education were independently associated with a lower hazard of SL, whereas older age and higher disease activity were associated with higher hazard of SL. The findings suggest a role of socioeconomic factors in adverse work outcomes, alongside active disease.

Copyright information: © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ., Objective: To investigate the determinants of impaired spinal and hip mobility in patients with early axial spondyloarthritis (axSpA). Methods: Five-year longitudinal data from the DEvenir des Spondyloarthrites Indifférenciées Récentes (DESIR) cohort were analysed. Associations were investigated using generalised estimating equations, using Bath Ankylosing Spondylitis Metrology Index (BASMI) linear or each of the five components of BASMI as dependent variables, and clinical and demographic variables as independent variables in univariable models. Multivariable analyses were performed, adjusting for potential confounders. Results: Data from 644 patients and 5152 visits were analysed. Higher BASMI values were independently and positively associated with Ankylosing Spondylitis Disease Activity Score C reactive protein (ASDAS-CRP) (adjusted B (adjB)=0.21; 95% CI=0.15 to 0.28), MRI spinal inflammation score (adjB=0.11; 95% CI=0.04 to 0.19), enthesitis score (adjB=0.02; 95% CI=0.01 to 0.04) and age (adjB=0.02; 95% CI=0.01 to 0.03). All BASMI components were independently associated with ASDAS-CRP and MRI spinal inflammation, except for maximal intermalleolar distance (reflecting hip mobility), which was not associated with MRI spinal inflammation. Conclusion: In early axSpA, spinal mobility impairment is independently determined by clinical disease activity, MRI spinal inflammation, enthesitis and age. The influence of spinal inflammation prevails in early axSpA, as opposed to spinal structural damage, which may become more relevant in later disease stages.

Objective There is an ongoing debate about excluding patient's global assessment (PtGA) from composite and Boolean-based definitions of rheumatoid arthritis (RA) remission. This study aimed at determining the influence of PtGA on RA disease states, exploring differences across countries, and understanding the association between PtGA, measures of disease impact (symptoms), and markers of disease activity (inflammation). Methods Cross-sectional data from the Measurement of Efficacy of Treatment in the Era of Outcome in Rheumatology international database were used. We calculated the proportion of patients failing American College of Rheumatology/European League Against Rheumatism Boolean-based remission (4-variable remission) solely due to PtGA (PtGA-near-remission) in the overall sample and in the most representative countries (i.e., those with >3,000 patients in the database). Multivariable linear regression models were used to identify the main determinants of PtGA, grouped in predominantly inflammatory impact factors (28 tender joint counts, 28 swollen joint counts, and C-reactive protein level) and disease impact factors (pain and function). Results This study included 27,768 patients. Excluding PtGA from the Boolean-based definition (3-variable remission) increased the remission rate from 5.8% to 15.8%. The rate of PtGA-near-remission varied considerably between countries, from 1.7% in India to 17.9% in Portugal. One-third of the patients in PtGA-near-remission group scored PtGA >4 of 10. Pain and function were the main correlates of PtGA, with inflammation-related variables contributing less to the model (R2 = 0.57). Conclusion PtGA is moderately related to joint inflammation overall, but only weakly so in low levels of disease activity. A considerable proportion of patients otherwise in biologic remission still perceive high PtGA, putting them at risk of excessive immunosuppressive treatment.

Objective To evaluate whether use of comedication with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) influences the retention of tumor necrosis factor inhibitors (TNFi) in patients with spondyloarthritis (SpA). Methods Patients with SpA from the Rheumatic Diseases Portuguese Register who started treatment with their first TNFi between 2001 and 2014 were included in this study. Cox regression analysis was used to estimate the effect of comedication with csDMARDs on TNFi retention in 2 types of models: a model in which baseline (time-fixed) variables were included, and a second model incorporating time-varying variables, including sociodemographic features, measures of disease activity, measures of physical function, and cotreatment with other drugs (nonsteroidal antiinflammatory drugs and oral steroids). To control for possible confounding by indication, the effect of csDMARD comedication on TNFi retention was also tested after adjustment for the treatment propensity score. Results In total, 954 patients were included in the study, of whom 289 (30.3%) discontinued treatment with their first TNFi after a median follow-up time of 2.5 years (range 0.08–13 years). Inefficacy was the most common reason for TNFi discontinuation (55.7% of patients). In the multivariable analyses, comedication with csDMARDs had no measurable effect on TNFi retention, neither in the baseline model (hazard ratio [HR] 0.83, 95% confidence interval [95% CI] 0.59–1.16) nor during follow-up in the model adjusted for time-varying covariates (HR 1.07, 95% CI 0.68–1.68). The effect of csDMARD comedication remained nonsignificant after propensity score adjustment. Conclusion Comedication with csDMARDs does not prolong TNFi retention in patients with SpA in clinical practice, suggesting that there is no benefit conferred by the concomitant use of these drugs.

Axial spondyloarthritis (axSpA) is a chronic inflammatory condition of the axial skeleton that encompasses radiographic and non-radiographic axSpA and that can lead to chronic pain, structural damage, disability, and loss of quality of life. Scientific advances, including the role of MRI assessment, have led to new diagnostic insights and the creation of a new set of classification criteria for axial and peripheral SpA. New criteria allow the identification of SpA patients with early disease and their enrolment in clinical studies. In this chapter, we discuss the difference between diagnostic and classification criteria, the diagnostic approach to patients with suspected axSpA, the limitations of MRI assessment, and the importance of early identification of this condition. A practical algorithm to investigate axSpA, based on the current evidence, is also proposed. Clinical judgement should always be kept as the mainstay in the diagnosis of axSpA.