Global Functioning in Axial Spondyloarthritis is Stronger Associated With Disease Activity and Function Than With Mobility and Radiographic Damage

Abstract

ObjectiveThe ASAS Health Index (ASAS HI) is a validated patient‐reported outcome (PRO) for global functioning of patients with axial spondyloarthritis (axSpA). The Epionics SPINE (ES) is an electronic device for assessment of axial mobility that provides an objective measure of spinal mobility by assessing range (RoM) and range of kinematic (RoK).The aim of this study is to investigate the relationship between global functioning and clinical measures of disease activity, physical function, spinal mobility, and radiographic damage.MethodsCross‐sectional study‐design, consecutive patients with radiographic (r) and non‐radiographic (nr)‐axSpA were included, and established tools were assessed: BASDAI, BASFI, BASMI, ASAS HI, RoM and RoK using ES. Structural damage of spine and SIJ were assessed by counting the number of syndesmophytes and by NY grading of sacroiliitis. Kendal's tau correlation‐coefficients were calculated.ResultsIn 103 axSpA patients, ASAS HI scores correlated significantly with PRO scores (BASDAI, r=0.36, BASFI, r=0.48 and back pain, r=0.41; all p<0.001). In contrast, no significant correlation between ASAS HI and ROM and ROK (r between ‐0.08 and 0.09) and radiographic damage in SIJ and spine (all r= between 0.03 and 0.004) were seen, respectively. BASMI scores correlated weakly (r=0.14, p=0.05).ConclusionThis study shows that axSpA disease specific PRO's have impact on global functioning whereas spinal mobility scores, even if objectively assessed by the ES, have limited impact on patient reported global functioning. The results also suggest that global functioning is, in this cohort, not much dependent on the degree of structural damage in the axial skeleton.This article is protected by copyright. All rights reserved.