Development of a health index in patients with ankylosing spondylitis (ASAS HI): final result of a global initiative based on the ICF guided by ASAS. Issue 5 (7th January 2014)

• Record Type: Journal Article
• Authors: Kiltz, U; van der Heijde, D; Boonen, A; Cieza, A; Stucki, G; Khan, M A; Maksymowych, W P; Marzo-Ortega, H; Reveille, J; Stebbings, S; Bostan, C; Braun, J
• Other Names: Barr Campbell collab.; van Drogen Cor collab.; Eustance Eric collab.; Feldtkeller Ernst collab.; Hattebuhr Britta collab.; Jongkees Merryn collab.; Kiltz Uta collab.; Mallinson Michael collab.; Mulholland Ken collab.; Özgocmen Salih collab.; Pianin Michael collab.; Staub Peter collab.; Supancich Michael collab.
• Is Part Of: Annals of the rheumatic diseases. Volume 74:Issue 5(2015)
• Page Start: 830
• Page End: 835
• Publication Date: 2014-01-07
• Subjects: Spondyloarthritis -- Ankylosing Spondylitis -- Outcomes research; Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2013-203967
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Objectives: The burden of disease in patients with ankylosing spondylitis (AS) can be considerable. However, no agreement has been reached among expert members of Assessment of SpondyloArthritis International Society (ASAS) to define severity of AS. Based on the International Classification of Functioning, Disability and Health (ICF), a core set of items for AS has been selected to represent the entire spectrum of possible problems in functioning. Based on this, the objective of this study was to develop a tool to quantify health in AS, the ASAS Health Index. Methods: First, based on a literature search, experts' and patients' opinion, a large item pool covering the categories of the ICF core set was generated. In several steps this item pool was reduced based on reliability, Rasch analysis and consensus building after two cross-sectional surveys to come up with the best fitting items representing most categories of the ICF core set for AS. Results: After the first survey with 1754 patients, the item pool of 251 items was reduced to 82. After selection by an expert committee, 50 items remained which were tested in a second cross-sectional survey. The results were used to reduce the number of items to a final set of 17 items. This selection showed the best reliability and fit to the Rasch model, no residual correlation, and absence of consistent differential item function and a Person Separation Index of 0.82. Conclusions: In this long sequential study, 17 items which cover most of the ICF core set were identified that showed the best representation of the health status of patients with AS. The ASAS Health Index is a linear composite measure which differs from other measures in the public domain.