Background Patients with ankylosing spondylitis (AS) suffer from pain, stiffness and fatigue, are limited in their activities and restricted in social participation as it is categorized in the International Classification of Functioning, Disability and Health (ICF). Awareness has grown that the experience of health is the product of the interaction between the disease related on the one hand and a series of contextual factors in the person and environment. Environmental factors (EF) are defined as elements external to the individual that can influence functioning and can be facilitators or barriers The most important EF for patients with AS has been identified in the ASAS (Assessments of SpondyloArthritis international Society) Core set for patients with AS. However, there is limited understanding of the relationship and it’s extend between EF and the health of patients with AS.

Objectives To select a core set of EF which influence importantly self-reported functioning in patients with AS.

Methods An item pool of candidate EF-items was developed by linking existing questionnaire-items to the EF-categories of the ASAS Core Set for AS. The label of being a barrier or a facilitator has been designated to each item. The EF item pool has been tested together with the item set of the ASAS Health Index (ASAS HI) in two cross-sectional studies. The selection of the EF item set is based on the correlation of each individual item to the sum score of the ASAS HI.

Results The initial item pool exists of 53 items addressing categories of e1 ‘products and technologies’, e3 ‘support and relationship’, e4 ‘attitudes’ and e5 ‘health services’. After the 1^st postal survey 37 items were deleted because of low non-significant correlation between EF item and ASAS HI sum score. Out of the remaining 16 items 9 were selected after the 2^nd postal survey to build the final EF item set. Of these, 3 items serves as a facilitator and 6 items serves as a barrier.

Conclusions The EF item set gives an overview on most important domains addressing support and relationship, attitudes of the patient and health services. Health professionals can assess with this pool in which areas the patient might need special assistance and researchers need to take EF into account when interpreting data on self-reported health. EF may often impact functioning not as single categories but as complex arrays of multiple EFs. Further research is needed to enlarge the understanding of the influence of EF as a complex area on health status in specific disease states.

References Boonen et al. ASAS/WHO ICF Core Sets for ankylosing spondylitis (AS): how to classify the impact of AS on functioning and health. Ann Rheum Dis 2010;69:102-107.

Disclosure of Interest None Declared