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

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.

Measurement properties of the ASAS Health Index: results of a global study in patients with axial and peripheral spondyloarthritis

“…The Assessment of Spondyloarthritis international Society Health Index (ASAS HI) has been developed to measure functioning and health in patients with SpA with the aim of defining and comparing the impact of the disease and health in this patient group 7. Initial phases in the development of the ASAS HI focused on investigating functional impairments from the patients’ perspective using both qualitative and quantitative approaches.…”

“…The sum score of the ASAS HI ranges from 0 to 17, with a lower score indicating a better health status. Preliminary validity and feasibility (time of completion) have already been assessed in a field test during the final steps of the development phase 7. Cognitive debriefing was undertaken in patients with AS and nr-axSpA and patients with peripheral manifestations aiming at assessment of a broad impact of health on all patients with SpA 7 10.…”

Instrumented BASFI (iBASFI) Shows Promising Reliability and Validity in the Assessment of Activity Limitations in Axial Spondyloarthritis

“…Similarly, the recently developed ASAS Health Index adopted patient-reported dichotomous (I agree/I do not agree) response options to evaluate the broader construct of "functioning" 13 . Unfortunately, this first implementation of the WHO/ASAS/ICF axSpA core sets 9,12 has failed to recognize the crucial distinction between what a person can do in a standardized environment (activities: capacity qualifier) versus in a real-life situation (participation: performance qualifier) 10 .…”

Validation of the Eq-5d-5l Version in Russia

“…Для оценки активности заболевания использовали индексы BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) [11] и ASDAS (Ankylosing Spondylitis Disease Activity Score) [12], для определения функцио-нального статуса -индекс BASFI (Bath Ankylosing Spondylitis Functional Index) [13], для оценки подвижно-сти позвоночника -метрологический индекс BASMI (Bath Ankylosing Spondylitis Metrology Index) [14]. Для комплексного анализа влияния СпА на здоровье па-циента был использован ASAS HI (АSАS Hеаlth Indеx -индекс здоровья ASAS) [15].…”