[German translation and cross-cultural adaptation of the ASAS health index : An ICF-based instrument for documentation of functional ability in patients with ankylosing spondylitis]. / Deutsche Übersetzung und krosskulturelle Adaptation des ASAS-Gesundheitsindex : Ein ICF-basiertes Instrument zur Erfassung der Funktionsfähigkeit von Patienten mit ankylosierender Spondylitis.

Documentation of the severity of the disease in patients with spondyloarthritis (SpA) can represent a clinical challenge, especially as the course of SpA can be very different. Patients with SpA often complain of symptoms, such as pain, fatigue and stiffness as well as limitations in mental functions and social participation. This wide range of functional impairments could so far only be insufficiently documented and not with one single measurement instrument. Despite various attempts in recent years, experts could not reach agreement on a definition of the severity and documentation of the extent of the severity. This was the starting point for the development of the ASAS health index presented here, which initially focused on patients with ankylosing spondylitis (AS). This questionnaire serves to document the health and functional ability of patients with AS and has been available since 2015 as the original english version of the ASAS health index together with the accompanying environmental factors set. This article describes the German translation and transcultural adaptation of the ASAS health index and the accompanying environmental factors set.

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.

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.

The ASAS Health Index (ASAS HI) - a new tool to assess the health status of patients with spondyloarthritis.

Within the variable course of ankylosing spondylitis (AS), peripheral arthritis, enthesitis, and involvement of other organs can add to the burden of the disease. The primary complaints of patients with spondyloarthritis (SpA) are pain, stiffness, fatigue, and limitation in activities and social participation. Instruments currently available for the assessment of patients with SpA focus predominantly on specific aspects of health such as pain, disease activity, and physical function and measure specific concepts like physical function and health-related quality of life (HR-QoL). However, the overall picture of impairments, limitations and restrictions in activities or social participation of patients with AS is not adequately assessed in SpA-specific questionnaires. Most of the existing questionnaires are not conceptualised with regard to their underlying construct. The International classification of functioning, disability and health (ICF) Core Set for AS may serve as an appropriate model and underlying construct to develop a health index, since the whole range of functioning and disability of patients with AS is captured. Based on these assumptions, ASAS developed for patients with SpA an instrument assessing health as operationalised by the ICF. The questionnaire was developed by preparing an item pool, linkage of the items to the comprehensive ICF core set for AS and test of the item pool in two cross-sectional studies. The analysis of the questionnaire and the response scale were done with Rasch analysis. Emphasis was on optimal targeting, the capacity of items to differentiate between different levels of health, and optimal coverage of items to the spectrum of ICF categories, so that the final questionnaire could represent as much of the entire range of difficulty levels as possible. The ASAS HI is a linear composite measure and includes 17 items which cover most of the ICF core set. Preliminary validity has been confirmed in a field test in 4 English-speaking countries. The ASAS HI should soon be used in clinical trials and in clinical practice to test its real life performance and to confirm that this new composite index captures relevant information on functioning and health of patients with AS.

Assessment of spinal pain.

Spinal pain or back pain is a very common symptom that can have many reasons. The most studied location is low back pain, and it is considered to be nonspecific in the majority of cases. Only a small proportion of patients have axial inflammation as the major cause of their back complaints with chronic inflammatory back pain (IBP) as the most prominent clinical feature of spondyloarthritis (SpA). The recognition of IBP and patients with axial spondyloarthritis (axSpA) is challenging in primary care, and it is important to further facilitate the early diagnosis of SpA. Proposals for improving the referral of patients with a possible diagnosis of axSpA include clinical parameters, human leukocyte antigen (HLA) B27, and imaging parameters. Imaging is crucial for the visualization, objective validation, and understanding of back pain. Numerous diseases such as degenerative disk disease, degenerative changes in the intervertebral (facet) joints and the associated ligaments, spinal instability, herniation of the intervertebral disk, and spinal stenosis have to be differentiated in interpreting imaging of the spine. The sacroiliac joints and the spine are of major importance for the diagnosis and classification of axSpA. Conventional radiographs and magnetic resonance imaging (MRI) are the most important imaging technologies for visualization of structural changes such as syndesmophytes and axial inflammation such as sacroiliitis and spondylitis. The pathogenesis of axSpA is largely genetically determined. HLA B27 has the strongest contribution to the total genetic burden, but other major contributors such as endoplasmic reticulum aminopeptidase (ERAP)-1 and interleukin (IL)-23R have also been identified.