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Measurement properties of the ASAS Health Index: results of a global study in patients with axial and peripheral spondyloarthritis
  1. Uta Kiltz1,
  2. Désirée van der Heijde2,
  3. Annelies Boonen3,
  4. Nurullah Akkoc4,
  5. Wilson Bautista-Molano5,
  6. Ruben Burgos-Vargas6,
  7. James Cheng-Chung Wei7,
  8. Praveena Chiowchanwisawakit8,
  9. Maxime Dougados9,
  10. M Tuncay Duruoz10,
  11. Bassel Kamal Elzorkany11,
  12. Inna Gaydukova12,
  13. Lianne S Gensler13,
  14. Michele Gilio14,
  15. Simeon Grazio15,
  16. Jieruo Gu16,
  17. Robert D Inman17,
  18. Tae-Jong Kim18,
  19. Victoria Navarro-Compan19,
  20. Helena Marzo-Ortega20,
  21. Salih Ozgocmen21,
  22. Fernando Pimentel dos Santos22,
  23. Michael Schirmer23,
  24. Simon Stebbings24,
  25. Filip E Van den Bosch25,26,
  26. Astrid van Tubergen3,
  27. Juergen Braun1
  1. 1 Rheumazentrum Ruhrgebiet, Herne, Germany
  2. 2 Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
  3. 3 Division of Rheumatology, Maastricht University Medical Center, Maastricht, The Netherlands
  4. 4 Izmir, Turkey
  5. 5 School of Medicine, Universidad Militar Nueva Granada and Rheumatology Department, Hospital Militar, Bogotà, Colombia
  6. 6 Hospital General de Mexico Universidad Nacional Autónoma, Mexico
  7. 7 Division of Allergy, Immunology and Rheumatology, Chung Shan Medical University Hospital, Institute of Medicine, Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan
  8. 8 Faculty of Medicine, Siriraj Hospital, Mahidol University, Thailand
  9. 9 Department of Rheumatology, Servicio de Reumatologia, Hôpital Cochin, Assistance Publique—Hôpitaux de Paris INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, H, Paris, France
  10. 10 PMR Department, Rheumatology Division, Marmara University School of Medicine, Istanbul, Turkey
  11. 11 Rheumatology Department, Cairo University, Cairo, Egypt
  12. 12 North-Western State Medical University named after I I Mechnikov, St. Petersburg, Russian Federation
  13. 13 Division of Rheumatology, University of California, San Francisco, San Francisco, California, USA
  14. 14 Department of Lucania, San Carlo Hospital of Potenza and Madonna delle Grazie Hospital of Matera, Potenza and Matera and PhD Scholarship in Life Sciences, Department of Health Sciences, University of Catanzaro ‘Magna Graecia’, Catanzaro, Italy
  15. 15 Sestre Milosrdnice University Hospital Center, Zagreb, Croatia
  16. 16 University of Guangzhou, Guangzhou, China
  17. 17 Spondylitis, University of Toronto, Toronto, Ontario, Canada
  18. 18 Chonnam National University Medical School and Hospital, South Korea
  19. 19 University Hospital La Paz, IdiPaz, Madrid, Spain
  20. 20 NIHR Leeds Biomedical Research Centre, Chapel Allerton Hospital, Leeds, and Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK
  21. 21 Department of Rheumatology, Medicalpark Gaziosmanpasa Hospital, Istanbul, Turkey
  22. 22 Universidade Nova De Lisboa, Lisbon, Portugal
  23. 23 Department of Internal Medicine, Innsbruck Medical University, Clinic II, Innsbruck, Austria
  24. 24 Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
  25. 25 VIB Center for Inflammation Research, Unit for Molecular Immunology and Inflammation, Department of Internal Medicine, Ghent University, Ghent, Belgium
  26. 26 Department of Rheumatology, Ghent University Hospital, Ghent, Belgium
  1. Correspondence to PD Dr Uta Kiltz, Rheumazentrum Ruhrgebiet, 44649 Herne, Germany; uta.kiltz{at}elisabethgruppe.de

Abstract

Objectives To evaluate construct validity, interpretability, reliability and responsiveness as well as determination of cut-off points for good and poor health within the original English version and the 18 translations of the disease-specific Assessment of Spondyloarthritis international Society Health Index (ASAS HI) in 23 countries worldwide in patients with spondyloarthritis (SpA).

Methods A representative sample of patients with SpA fulfilling the ASAS classification criteria for axial (axSpA) or peripheral SpA was used. The construct validity of the ASAS HI was tested using Spearman correlation with several standard health outcomes for axSpA. Test–retest reliability was assessed by intraclass correlation coefficients (ICCs) in patients with stable disease (interval 4–7 days). In patients who required an escalation of therapy because of high disease activity, responsiveness was tested after 2–24weeks using standardised response mean (SRM).

Results Among the 1548 patients, 64.9% were men, with a mean (SD) age 42.0 (13.4) years. Construct validity ranged from low (age: 0.10) to high (Bath AnkylosingSpondylitisFunctioning Index: 0.71). Internal consistency was high (Cronbach’s α of 0.93). The reliability among 578 patients was good (ICC=0.87 (95% CI 0.84 to 0.89)). Responsiveness among 246 patients was moderate-large (SRM=−0.44 for non-steroidal anti-inflammatory drugs, −0.69 for conventional synthetic disease-modifying antirheumatic drug and −0.85 for tumour necrosis factor inhibitor). The smallest detectable change was 3.0. Values ≤5.0 have balanced specificity to distinguish good health as opposed to moderate health, and values ≥12.0 are specific to represent poor health as opposed to moderate health.

Conclusions The ASAS HI proved to be valid, reliable and responsive. It can be used to evaluate the impact of SpA and its treatment on functioning and health. Furthermore, comparison of disease impact between populations is possible.

  • spondyloarthritis
  • ankylosing spondylitis
  • outcomes research

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Footnotes

  • Handling editor Tore K Kvien

  • Contributors Study concept and design: UKU, DvdH, AB, JB. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Writing of the manuscript: UKU. Critical revision of the manuscript for important intellectual content: all authors. All authors had access to the data, commented on the report drafts and approved the final submitted version.

  • Funding This study was funded by the Assessment of Spondyloarthritis international Society (ASAS).

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval All centres received approval from their local ethics committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Correction notice This article has been corrected since it published Online First. The acknowledgements statement has been updated.

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