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

OBJECTIVE: The Assessment of Spondyloarthritis International Society 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 of motion (RoM) and range of kinematics (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. METHODS: In a cross-sectional study design, consecutive patients with radiographic and nonradiographic axSpA were included, and the following established tools were assessed: Bath ankylosing spondylitis (AS) disease activity index (BASDAI), Bath AS functional index (BASFI), Bath AS metrology index (BASMI), ASAS HI, and RoM and RoK using ES. Structural damage of spine and sacroiliac joints (SIJ) were assessed by counting the number of syndesmophytes and by New York grading of sacroiliitis. Kendall's tau correlation coefficients were calculated. RESULTS: In 103 patients with axSpA, 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). CONCLUSION: This study shows that axSpA disease-specific PROs have an 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.

Clinical Relevance of Axial Radiographic Damage in Axial Spondyloarthritis: Evaluation of Functional Consequences by an Objective Electronic Device.

OBJECTIVE: Axial spondyloarthritis (axSpA) is associated with decreased function and mobility of patients as a result of inflammation and radiographic damage. The Epionics SPINE device (ES), an electronic device that objectively measures spinal mobility, including range of motion (RoM) and speed (ie, range of kinematics [RoK]) of movement, has been clinically validated in axSpA. We investigated the performance of the ES relative to radiographic damage in the axial skeleton of patients with axSpA. METHODS: A total of 103 patients with axSpA, 31 with nonradiographic axSpA (nr-axSpA) and 72 with radiographic axSpA (r-axSpA), were consecutively examined. Conventional radiographs of the spine (including presence, number, and location of syndesmophytes) and the sacroiliac joints (SIJs; rated by the modified New York criteria) were analyzed with the ES. Function and mobility were assessed using analyses of covariance and Spearman correlation. RESULTS: The number of syndesmophytes correlated positively with Bath Ankylosing Spondylitis Metrology Index scores (r 0.38, P = 0.02) and correlated negatively with chest expansion (r -0.39, P = 0.02) and ES measurements (-0.53 ≤ r ≤ -0.34, all P < 0.03), except for RoM and RoK regarding rotation and RoK for extension of the lumbar and thoracic spines. In the radiographic evaluation of the SIJs, the extent of damage correlated negatively with ES scores and metric measurements (-0.49 ≤ r ≤ -0.33, all P < 0.001). Patients with r-axSpA, as compared to those with nr-axSpA, showed significantly worse ES scores for RoM, RoK, and chest expansion. CONCLUSION: The ES scores, in accordance with mobility measurements, correlated well with the presence and extent of radiographic damage in the spine and the SIJs. As expected, patients with r-axSpA had more severe impairments than those with nr-axSpA.

Successful Evaluation of Spinal Mobility Measurements With the Epionics SPINE Device in Patients With Axial Spondyloarthritis Compared to Controls.

OBJECTIVE: Epionics SPINE (ES), a novel device that measures spinal movements using electronic sensors including range of motion (RoM) and speed (range of kinematics [RoK]), has already been validated in patients with mechanical back pain and healthy individuals. This study aimed to evaluate ES for quantification of spinal mobility in patients with axial spondyloarthritis (axSpA). METHODS: A total of 153 individuals, 39 female and 114 male, were examined including 134 patients with axSpA, of whom 40 had nonradiographic (nr)-axSpA, 94 had radiographic (r)-axSpA; 19 were healthy controls (HCs). The results were compared using mean ES scores and modeling was performed using multivariable logistic regression models resulting in good validity and high discriminative power. RESULTS: ES measurements showed meaningful differences between patients with axSpA and HCs (all P < 0.001), as well as between r- and nr-axSpA (P < 0.01). In patients with axSpA, a negative correlation between ES and Bath Ankylosing Spondylitis Metrology Index values was found: -0.76 ≤ r ≤ -0.52 (P < 0.05). Bath Ankylosing Spondylitis Functional Index scores showed a similar trend (r > -0.39). Patients with r-axSpA had a more limited and slower spinal mobility than those with nr-axSpA. Other patient-reported outcomes almost did not correlate. CONCLUSION: This study shows that the ES is an objective performance measure and a valid tool to assess spinal mobility in axSpA, also based on the Outcomes Measures in Rheumatology (OMERACT) criteria. RoK and RoM scores provide additional information on physical function of patients with axSpA.