FEAR OF MOVEMENT MEDIATES THE RELATIONSHIP BETWEEN PAIN CATASTROPHISING AND PHYSICAL FUNCTION IN PEOPLE LIVING WITH AXIAL SPONDYLOARTHRITIS: A CROSS-SECTIONAL MEDIATION ANALYSIS

Background Axial spondyloarthritis (axSpA) typically affects the axial skeleton and sacroiliac joints causing patients to experience pain, reduced movement, and impaired physical function. A range of treatment options are available to help axSpA patients reduce pain and maintain physical function and thereby enhance health-related quality of life. The European Alliance of Associations for Rheumatology (EULAR) identified activity as integral to the management of inflammatory arthritides, however, the majority of people living with axSpA are not sufficiently active to maintain physical function [1]. According to the Fear-Avoidance Model of Pain, fear of movement and pain catastrophizing contribute to poorer physical function via reduced activity and disuse [2]. Yet to date, no research has tested the theorized mediating role of fear of movement in the relationship between pain catastrophizing and physical function in people living with axSpA.

Objectives To examine the mediating role of fear of movement in the relationship between pain catastrophizing and physical function in people living with axSpA.

Methods Participants (N = 98, 70% female, M Age = 45.62 SD 12.16) completed an online survey (December 2020 – May 2021) distributed in the United Kingdom via the National Axial Spondyloarthritis Society (n ≈ 3,500; NASS, 2019). The Tampa Scale for Kinesiophobia (TSK-11) was used to measure fear of movement with participants rating 11-items from 1 (strongly disagree) to 4 (strongly agree). The Pain Catastrophising Scale (PCS) contains 13-items, each rated on a scale from 0 (not at all) to 4 (all the time). Both instruments have shown strong internal consistency in people living with axSpA [3,4]. The Bath Ankylosing Spondylitis Functional Index (BASFI) was used to assess physical function with higher scores indicating poorer function. Data were analysed using IBM SPSS (Version 28). The PROCESS SPSS macro was used, and interpretation made using the percentile bootstrap 95% confidence intervals from 5000 bootstrap samples. Standardised effects with values.01,.09, and.25 represent small, medium, and large effects [5].