OBJECTIVE: The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is widely used for assessing disease activity in patients with axial spondyloarthritis (axSpA), particularly in settings where markers of inflammation are unavailable. As no consensus on BASDAI cut-off values exists for disease activity states in axSpA, we aimed to develop and validate such cut-offs against external criteria. METHODS: Routine care patients with axSpA initiating a biologic disease-modifying antirheumatic drug in eight European registries were included. Receiver operating characteristic analyses against external criteria were performed to determine optimal BASDAI values for separating remission, low disease activity (LDA), high disease activity (HDA), and very high disease activity (VHDA). Follow-up data at 6 months were used to select BASDAI cut-off values between remission and LDA and between LDA and HDA, whereas baseline data were used to select the cut-off for VHDA. The level of agreement between disease activity states based on BASDAI and Axial Spondyloarthritis Disease Activity Score (ASDAS) cut-off values was assessed using the proportion of discordance and weighted kappa. RESULTS: In this cohort of 4,633 patients, the optimal BASDAI cut-off values between remission, LDA, HDA and VHDA were estimated to be <1.3, <2.5, and >5.3. The proportions of discordance between BASDAI and ASDAS disease activity states were 27.6% (weighted κ = 0.48) in baseline data and 37.6% (weighted κ = 0.28) in 6-month data. CONCLUSION: BASDAI cut-off values for separating remission, LDA, HDA and VHDA were estimated in >4,600 patients. These cut-off values can be used for assessing disease activity and monitoring patients with axSpA, particularly when laboratory markers are unavailable.

Aarhus University Hospital and Aarhus University Aarhus Denmark

Centre for Rheumatic Disease Tampere University Hospital and Tampere University Tampere Finland

Centre for Rheumatology Research Landspitali University Hospital and University of Iceland Reykjavik Iceland

Clinical Epidemiology Division Department of Medicine Solna Karolinska Institutet Stockholm Sweden

COPECARE Center for Rheumatology and Spine Diseases Centre for Head and Orthopaedics and DANBIO Rigshospitalet Glostrup and the University of Copenhagen Copenhagen Denmark

COPECARE Center for Rheumatology and Spine Diseases Centre for Head and Orthopaedics Rigshospitalet Glostrup and the University of Copenhagen Copenhagen Denmark

COPECARE Center for Rheumatology and Spine Diseases Centre for Head and Orthopaedics Rigshospitalet Glostrup Denmark and Center for Treatment of Rheumatic and Musculoskeletal Diseases Diakonhjemmet Hospital Oslo and Sørlandet Hospital Kristiansand Norway

Copenhagen Center for Arthritis Research Center for Rheumatology and Spine Diseases Centre for Head and Orthopaedics Rigshospitalet Glostrup Denmark

EpiDoC unit Comprehensive Health Research Centre Nova Medical School and Reuma pt Sociedade Portuguesa de Reumatologia Lisbon Portugal

Geneva University Hospital Geneva Switzerland

German Rheumatology Research Center Berlin Germany

Hospital Garcia de Orta Almada and Instituto Medicina Molecular Faculdade de Medicina da Universidade de Lisboa Centro Académico de Medicina de Lisboa Lisbon Portugal

Institute of Rheumatology and 1st Faculty of Medicine Charles University Prague Czech Republic

REMEDY Diakonhjemmet Hospital and the University of Oslo Oslo Norway

Turku University Hospital and the University of Turku Turku Finland

University Hospital Zurich and the University of Zurich Zurich Switzerland

University Medical Centre Ljubljana and the University of Ljubljana Ljubljana Slovenia

University of Iceland Reykjavik Iceland and the Department of Clinical Sciences Lund Rheumatology Lund University and Skåne University Hospital Lund Sweden

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Rudwaleit M, van der Heijde D, Landewé R, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis 2009;68(6):777–783. PubMed

Sieper J, Poddubnyy D. Axial spondyloarthritis. Lancet 2017;390(10089):73–84. PubMed

Ward MM, Deodhar A, Gensler LS, et al. 2019 Update of the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network recommendations for the treatment of ankylosing spondylitis and nonradiographic axial spondyloarthritis. Arthritis Rheumatol 2019;71(10):1599–1613. PubMed PMC

Ramiro S, Nikiphorou E, Sepriano A, et al. ASAS‐EULAR recommendations for the management of axial spondyloarthritis: 2022 update. Ann Rheum Dis 2022;17:1–16. PubMed

Garrett S, Jenkinson T, Kennedy LG, et al. A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index. J Rheumatol 1994;21(12):2286–2291. PubMed

Lukas C, Landewé R, Sieper J, et al; Assessment of SpondyloArthritis international Society. Development of an ASAS‐endorsed disease activity score (ASDAS) in patients with ankylosing spondylitis. Ann Rheum Dis 2009;68(1):18–24. PubMed

van der Heijde D, Lie E, Kvien TK, et al; Assessment of SpondyloArthritis international Society (ASAS). ASDAS, a highly discriminatory ASAS‐endorsed disease activity score in patients with ankylosing spondylitis. Ann Rheum Dis 2009;68(12):1811–1818. PubMed

van der Heijde D, Molto A, Ramiro S, et al. Goodbye to the term ‘ankylosing spondylitis’, hello ‘axial spondyloarthritis’: time to embrace the ASAS‐defined nomenclature. Ann Rheum Dis 2024;83(5):547–549. PubMed

Machado P, Navarro‐Compán V, Landewé R, et al. Calculating the ankylosing spondylitis disease activity score if the conventional C‐reactive protein level is below the limit of detection or if high‐sensitivity C‐reactive protein is used: an analysis in the DESIR cohort. Arthritis Rheumatol 2015;67(2):408–413. PubMed

Smolen JS, Schöls M, Braun J, et al. Treating axial spondyloarthritis and peripheral spondyloarthritis, especially psoriatic arthritis, to target: 2017 update of recommendations by an international task force. Ann Rheum Dis 2018;77(1):3–17. PubMed PMC

Fagerli KM, Lie E, van der Heijde D, et al. Selecting patients with ankylosing spondylitis for TNF inhibitor therapy: comparison of ASDAS and BASDAI eligibility criteria. Rheumatology (Oxford) 2012;51(8):1479–1483. PubMed

Marona J, Sepriano A, Rodrigues‐Manica S, et al. Eligibility criteria for biologic disease‐modifying antirheumatic drugs in axial spondyloarthritis: going beyond BASDAI. RMD Open 2020;6(1):e001145. PubMed PMC

Robinson PC, Maksymowych WP, Gensler LS, et al. Certolizumab pegol efficacy in patients with non‐radiographic axial spondyloarthritis stratified by baseline MRI and C‐reactive protein status: an analysis from the C‐axSpAnd study. ACR Open Rheumatol 2022;4(9):794–801. PubMed PMC

Kiltz U, van der Heijde D, Boonen A, et al. Clinimetric validation of the Assessment of Spondyloarthritis International Society Health Index in patients with radiographic axial spondyloarthritis in ixekizumab trials. J Rheumatol 2023;50(6):754–762. PubMed

Rusman T, van der Weijden M, Nurmohamed MT, et al. Does a short course of etanercept influence disease progression and radiographic changes in patients suspected of non‐radiographic axial spondyloarthritis? Three‐years follow‐up of a placebo‐controlled trial. Scand J Rheumatol 2023;52(2):137–141. PubMed

Maksymowych WP, Thom H, Mørup MF, et al. Matching‐adjusted indirect comparison of the 52‐week efficacy of bimekizumab versus secukinumab and ixekizumab for the treatment of radiographic axial spondyloarthritis. Rheumatol Ther 2024;11(4):1023–1041. PubMed PMC

Ramiro S, van der Heijde D, van Tubergen A, et al. Higher disease activity leads to more structural damage in the spine in ankylosing spondylitis: 12‐year longitudinal data from the OASIS cohort. Ann Rheum Dis 2014;73(8):1455–1461. PubMed

Machado P, Landewé R, Lie E, et al; Assessment of SpondyloArthritis international Society. Ankylosing Spondylitis Disease Activity Score (ASDAS): defining cut‐off values for disease activity states and improvement scores. Ann Rheum Dis 2011;70(1):47–53. PubMed

Chen YH, Huang WN, Chen YM, et al. The BASDAI cut‐off for disease activity corresponding to the ASDAS scores in a Taiwanese cohort of ankylosing spondylitis. Front Med (Lausanne) 2022;9:856654. PubMed PMC

Kwon OC, Park MC. BASDAI cut‐off values corresponding to ASDAS cut‐off values. Rheumatology (Oxford) 2022;61(6):2369–2374. PubMed

Cui R, Du Y, Tian N, et al. Equivalent cut‐off values of Bath Ankylosing Spondylitis Disease Activity Index corresponding to Ankylosing Spondylitis Disease Activity Score cut‐off values. Clin Exp Rheumatol 2023;41(5):1163–1169. PubMed

Goswami RP, Chatterjee M, Das S. Defining Objective BASDAI cut‐offs for disease activity states and improvement scores in axial spondyloarthritis: a multicentric collaboration. Int J Rheum Dis 2024;27(11):e15418. PubMed

Ørnbjerg LM, Brahe CH, Askling J, et al. Treatment response and drug retention rates in 24 195 biologic‐naïve patients with axial spondyloarthritis initiating TNFi treatment: routine care data from 12 registries in the EuroSpA collaboration. Ann Rheum Dis 2019;78(11):1536–1544. PubMed

Linde L, Ørnbjerg LM, Rasmussen SH, et al. Commonalities and differences in set‐up and data collection across European spondyloarthritis registries — results from the EuroSpA collaboration. Arthritis Res Ther 2023;25(1):1–14. PubMed PMC

Machado PM, Landewé R, Heijde DV; Assessment of SpondyloArthritis international Society (ASAS). Ankylosing Spondylitis Disease Activity Score (ASDAS): 2018 update of the nomenclature for disease activity states. Ann Rheum Dis 2018;77(10):1539–1540. PubMed

Machado P, Landewé R, Lie E, et al; Assessment of SpondyloArthritis international Society. Ankylosing Spondylitis Disease Activity Score (ASDAS): defining cut‐off values for disease activity states and improvement scores. Ann Rheum Dis 2011;70(1):47–53. PubMed

Ørnbjerg LM, Georgiadis S, Kvien TK, et al. Impact of patient characteristics on ASDAS disease activity state cut‐offs in axial spondyloarthritis: results from nine European rheumatology registries. RMD Open 2024;10(4):e004644. PubMed PMC

Anderson JJ, Baron G, van der Heijde D, et al. Ankylosing spondylitis assessment group preliminary definition of short‐term improvement in ankylosing spondylitis. Arthritis Rheum 2001;44(8):1876–1886. PubMed

Perkins NJ, Schisterman EF. The inconsistency of “optimal” cutpoints obtained using two criteria based on the receiver operating characteristic curve. Am J Epidemiol 2006;163(7):670–675. PubMed PMC

Davison. AC , Hinkley D V. Bootstrap Methods and Their Application. Cambridge University Press; 1997.

R Core Team . R: a language and environment for statistical computing. Accessed July 31, 2025. https://www.r-project.org/

Landewé R, van Tubergen A. Clinical tools to assess and monitor spondyloarthritis. Curr Rheumatol Rep 2015;17(7):47. PubMed PMC

Vastesaeger N, Cruyssen BV, Mulero J, et al; REGISPONSER Working Group . ASDAS high disease activity versus BASDAI elevation in patients with ankylosing spondylitis as selection criterion for anti‐TNF therapy. Reumatol Clin 2014;10(4):204–209. PubMed

Michielsens C, Bolhuis TE, van Gaalen FA, et al. Construct validity of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS) treatment target cut‐offs in a BASDAI treat‐to‐target axial spondyloarthritis cohort: a cross‐sectional study. Scand J Rheumatol 2024;53(3):180–187. PubMed

Baraliakos X, Brandt J, Listing J, et al. Outcome of patients with active ankylosing spondylitis after two years of therapy with etanercept: clinical and magnetic resonance imaging data. Arthritis Rheum 2005;53(6):856–863. PubMed

Baraliakos X, Listing J, Brandt J, et al. Clinical response to discontinuation of anti‐TNF therapy in patients with ankylosing spondylitis after 3 years of continuous treatment with infliximab. Arthritis Res Ther 2005;7(3):R439–R444. PubMed PMC

Koo BS, Oh JS, Park SY, et al. Relationship between inflammation and radiographic progression in patients with ankylosing spondylitis attaining a BASDAI of less than 4 during tumor necrosis factor inhibitor treatment. J Rheumatol 2022;49(12):1328–1334. PubMed

Braun J, Baraliakos X, Kiltz U, et al. Disease activity cutoff values in initiating tumor necrosis factor inhibitor therapy in ankylosing spondylitis: a German GO‐NICE study subanalysis. J Rheumatol 2020;47(1):35–41. PubMed

Öztürk Ö, Feyzioğlu Ö, Sarıtaş F. Identifying frailty and its associated factors in patients with axial spondyloarthritis. Int J Rheum Dis 2023;26(3):519–530. PubMed

Bolt JW, Aalbers CJ, Walet L, et al. Treatment decisions in axial spondyloarthritis daily clinical practice are more than treat‐to‐target. Rheumatology (Oxford) 2024;63(1):34–40. PubMed PMC

Fongen C, Dagfinrud H, Bilberg A, et al. Reduced sleep quality is highly prevalent and associated with physical function and cardiorespiratory fitness in patients with axial spondyloarthritis: a cross‐sectional study. Scand J Rheumatol 2024;53(2):130–139. PubMed

Labinsky H, May S, Boy K, et al. Evaluation of a hybrid telehealth care pathway for patients with axial spondyloarthritis including self‐sampling at home: results of a longitudinal proof‐of‐concept mixed‐methods study (TeleSpactive). Rheumatol Int 2024;44(6):1133–1142. PubMed PMC

Aranda‐Valera IC, Garrido‐Castro JL, Ladehesa‐Pineda L, et al. How to calculate the ASDAS based on C‐reactive protein without individual questions from the BASDAI: the BASDAI‐based ASDAS formula. Rheumatology (Oxford) 2020;59(7):1545–1549. PubMed

Zhao SS, Jones GT, Macfarlane GJ, et al. Association between comorbidities and disease activity in axial spondyloarthritis: results from the BSRBR‐AS. Rheumatology (Oxford) 2021;60(7):3189–3198. PubMed PMC

van der Linden S, Valkenburg HA, Cats A. Evaluation of diagnostic criteria for ankylosing spondylitis. A proposal for modification of the New York criteria. Arthritis Rheum 1984;27(4):361–368. PubMed