Measuring spinal mobility in early axial spondyloarthritis: does it matter?

Clinically relevant differences in spinal mobility related to daytime performance in patients with axial spondyloarthritis

OBJECTIVE

Patients with axial spondyloarthritis (axSpA) suffer from clinical symptoms like morning stiffness and back pain. Mobility of patients with axSpA is often impaired. The aim of this study is to compare the performance of patients with axSpA regarding mobility measures including performance-based tests and objective electronic assessments with the Epionics SPINE device (ES) at different times of the day compared with healthy controls (HC).

METHODS

Observational trial, consecutive inpatients with axSpA (n=100) and 20 HCs were examined in the morning (V1: before 10:00 am) and in the afternoon (V2: after 02:00 pm) by the Bath Ankylosing Spondylitis Metrology Index (BASMI), the AS physical performance index (ASPI), the Short Physical Performance Battery (SPPB) and ES measurements, including range of motion (RoM) and range of kinematics (RoK).

RESULTS

The assessments of patients with axSpA performed in the morning clearly differed from those in the afternoon, especially regarding performance-based tests. Significant improvements were seen for BASMI (4.0±3.8 to 3.8±1.9; p<0.001), ASPI (36.2±18.3 to 28.8±11.9 s; p<0.001), SPPB (10.1±1.5 to 10.7±1.4 points; p<0.001) and for ES measures of speed (RoK; p<0.018) but not for RoM, except for lateral flexion (13.3±7.4 to 14.7±8.2°; p=0.002). This time of assessment-related variability was not observed in HC.

CONCLUSION

The spinal mobility of patients with axSpA was worse in the morning but significantly improved in the afternoon. This was captured best by performance-based measures and was not seen in HC. The diurnal variation of mobility has implications for clinical studies, suggesting that the time of assessments needs to be standardised.

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.

Impact of sex and gender on axSpA diagnosis and outcomes

Axial spondyloarthritis (axSpA) was historically considered a disease of men, largely due to the recognition of a more severe, progressive phenotype, ankylosing spondylitis (AS; or radiographic axSpA, r-axSpA) aiding the clinical diagnosis [1,2]. Data demonstrating the near equal prevalence of axSpA in women only started to emerge in the last decades, highlighting intrinsic differences in disease phenotype, and clinical and imaging characteristics between sexes, which partly explain the issue of underdiagnosis in women. Similar to the evolving understanding of spondyloarthritis and the diseases that term describes, the concepts of gender and sex also warrant further clarification to accurately assess their potential role in disease pathophysiology and phenotypic expression. This narrative review delves into the most recent evidence from the literature on the true prevalence of sex differences in axSpA, and the impact of sex and gender on diagnosis, disease characteristics and treatment response in this, still underserved, chronic disease.

ASAS consensus definition of early axial spondyloarthritis

OBJECTIVES

To develop a consensual definition for the term 'early axial spondyloarthritis-axSpA'-and 'early peripheral spondyloarthritis-pSpA'.

METHODS

The ASAS (Assessment of SpondyloArthritis international Society-Spondyloarthritis EARly definition) steering committee convened an international working group (WG). Five consecutive steps were followed: (1) systematic literature review (SLR); (2) discussion of SLR results within the WG and ASAS community; (3) a three-round Delphi survey inviting all ASAS members to select the items that should be considered for the definition; (4) presentation of Delphi results to the WG and ASAS community and (5) ASAS voting and endorsement (2023 annual meeting).

RESULTS

Following the SLR, consensus was to proceed with an expert-based definition for early axSpA (81% in favour) but not for pSpA (54% against). Importantly, early axSpA should be based on symptom duration taking solely axial symptoms into account. 151-164 ASAS members participated in the Delphi surveys. Consensus was achieved for considering the following items within early axSpA definition: duration of symptoms ≤2 years; axial symptoms defined as cervical/thoracic/back/buttock pain or morning stiffness; regardless of the presence/absence of radiographic damage. The WG agreed that in patients with a diagnosis of axSpA 'early axSpA' should be defined as a duration of ≤2 years of axial symptoms. Axial symptoms should include spinal/buttock pain or morning stiffness and should be considered by a rheumatologist as related to axSpA. The ASAS community endorsed this proposal (88% in favour).

CONCLUSIONS

Early axSpA has newly been defined, based on expert consensus. This ASAS definition should be adopted in research studies addressing early axSpA.

Good construct validity of the CT Syndesmophyte Score (CTSS) in patients with radiographic axial spondyloarthritis

OBJECTIVES

To assess construct validity of the CT Syndesmophyte Score (CTSS) for the measurement of structural spinal damage in patients with radiographic axial spondyloarthritis.

METHODS

Low-dose CT and conventional radiography (CR) were performed at baseline and 2 years. CT was assessed with CTSS by two readers and CR with modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) by three readers. Two hypotheses were tested: (1) syndesmophytes scored with CTSS are also detected with mSASSS at baseline or 2 years later; (2) CTSS is non-inferior to mSASSS in correlations with spinal mobility measures. Presence of a syndesmophyte was determined per reader per corner for all anterior cervical and lumbar corners on CT at baseline and CR at baseline and 2 years. Correlations of CTSS and mSASSS with six spinal/hip mobility measurements plus Bath Ankylosing Spondylitis Metrology Index (BASMI) were tested.

RESULTS

Data from 48 patients (85% male, 85% HLA-B27+, mean age 48 years) were available for hypothesis 1 and 41/48 were available for hypothesis 2. At baseline, syndesmophytes were scored with CTSS in 348 (reader 1, 38%) and 327 (reader 2, 36%) corners out of 917. Of these, depending on reader pairs, 62%-79% were also seen on CR at baseline or after 2 years. CTSS correlated well (r_s 0.46-0.73), and with higher correlation coefficients than mSASSS (r_s 0.34-0.64), with all spinal mobility measures and BASMI.

CONCLUSIONS

The good agreement between syndesmophytes detected by CTSS and mSASSS and the strong correlation of CTSS with spinal mobility support the construct validity of the CTSS.

Both ASDAS and ADC are associated with spinal mobility in active axial spondyloarthritis: A comparison between early and later disease

OBJECTIVE

Using diffusion-weighted imaging (DWI)-derived apparent diffusion coefficient (ADC), we aimed to determine the relationship between intensity of spinal inflammation and mobility in patients with axial spondyloarthritis (SpA) in early and later stages of active disease. The Ankylosing Spondylitis Disease Activity Score (ASDAS) was also used for a more comprehensive evaluation.

METHODS

Participants with axial SpA and back pain were recruited from 10 rheumatology centers. Clinical, biochemical and radiological parameters were collected. Short tau inversion recovery (STIR) sequence magnetic resonance imaging (MRI) and DWI of the spine and sacroiliac (SI) joints were performed. ADC maps were generated. Participants were examined for Bath Ankylosing Spondylitis Metrology Index (BASMI). Linear regression models were used to determine associations between BASMI and various clinical, radiological, and MRI parameters in participants with active inflammation on spinal ADC maps.

RESULTS

One-hundred and twenty-seven participants were included in the analyses. Multivariate linear regression showed that mean ADC spine (ß = .16; P = .03), ASDAS-C-reactive protein (CRP) (ß = .29, P < .001), and ASDAS-erythrocyte sedimentation rate (ESR) (ß = .25, P < .01) were associated with BASMI. In participants with duration of back pain ≤3 years, mean spine ADC (ß = .37; P = .03), ASDAS-CRP (ß = .44; P = .01), and ASDAS-ESR (ß = .42; P = .01) were associated with BASMI after adjustment for confounding factors. In participants with duration of back pain >3 years, only ASDAS-CRP (ß = .25; P < .01) and ASDAS-ESR (ß = .20; P = .20) were associated with BASMI.

CONCLUSION

Intensity of inflammation and clinical disease activity were independently associated with impairment of spinal mobility. The associations were stronger in early (≤3 years) than later disease.

Test-retest reliability of outcome measures: data from three trials in radiographic and non-radiographic axial spondyloarthritis

Objectives

Aim of this study was to assess test–retest reliability of candidate instruments for the mandatory domains of the Assessment of Spondyloarthritis international Society (ASAS)-Outcome Measures in Rheumatology core set for axial spondyloarthritis (axSpA).

Methods

Screening and baseline data from COAST-V, COAST-X and RAPID-axSpA was used to evaluate test–retest reliability of each candidate instrument for the mandatory domains (disease activity, pain, morning stiffness, fatigue, physical function, overall functioning and health). A maximum time interval of 28 days between both visits was used for inclusion in this study. Test–retest reliability was assessed by intraclass correlation coefficient (ICC). Bland and Altman plots provided mean difference and 95% limits of agreement, which were used to calculate the smallest detectable change (SDC). Data were analysed for radiographic and non-radiographic axSpA separately.

Results

Good reliability was found for Ankylosing Spondylitis Disease Activity Score (ICC 0.79, SDC 0.6), C reactive protein (ICC 0.72–0.79, SDC 12.3–17.0), Bath Ankylosing Spondylitis Functional Index (ICC 0.87, SDC 1.1) and 36-item Short-Form Health Survey (ICC Physical Component Summary 0.81, SDC 4.7, Mental Component Summary 0.80, SDC 7.3). Moderate reliability was found for Bath Ankylosing Spondylitis Disease Activity Index (ICC 0.72, SDC 1.1), patient global assessment (ICC 0.58, SDC 1.5), total back pain (ICC 0.64, SDC 1.3), back pain at night (ICC 0.67, SDC 1.3), morning stiffness (ICC 0.52–0.63, SDC 1.5–2.2), fatigue (ICC 0.65, SDC 1.3) and ASAS-Health Index (ICC 0.74, SDC 2.5). Reliability and SDC for the radiographic and non-radiographic axSpA subgroups were similar.

Conclusion

Overall reliability was good, and comparable levels of reliability were found for patients with radiographic and non-radiographic axSpA, even though most instruments were developed for radiographic axSpA. Composite measures showed higher reliability than single-item measures in assessing disease activity in patients with axSpA.

Clinical Manifestations and Diagnosis of Axial Spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is a chronic, rheumatic disease characterized by inflammation of the sacroiliac joint, spine, and entheses. Axial spondyloarthritis affects up to 1.4% of adults in the United States and is associated with decreased quality of life, increased mortality, and substantial health care-related costs, imposing a high burden on patients, their caregivers, and society.

SUMMARY OF WORK

Diagnosing axSpA can be difficult. In this review, we seek to help rheumatologists in recognizing and diagnosing axSpA.

MAJOR CONCLUSIONS

A discussion of challenges associated with diagnosis is presented, including use and interpretation of imaging, reasons for diagnostic delays, differences in disease presentation by sex, and differential diagnoses of axSpA.

FUTURE RESEARCH DIRECTIONS

The early diagnosis of axSpA and advances in available therapeutic options have improved patient care and disease management, but delays in diagnosis and treatment remain common. Additional research and education are critical for recognizing diverse axSpA presentations and optimizing management early in the course of disease.

Treat-to-target in axial spondyloarthritis - what about physical function and activity?

In patients with axial spondyloarthritis (axSpA), pain, functional and structural impairments, reduced mobility and potential deformity of the axial skeleton are the most prominent health concerns. Limitations in physical function and spinal mobility are caused by both inflammation and structural damage, and therefore restrictions to physical function must be monitored throughout a patient's life. Consequently, the assessment of physical function is recommended as a key domain in the Assessment of Spondyloarthritis International Society-OMERACT Core Outcome Set. However, in comparison with disease activity, physical function seems to be a relatively neglected target of intervention in patients with axSpA, even though physical function is a major contributor to costs and disability in this disease. This Review aims to reacquaint rheumatologists with the targets for physical function, physical activity and performance by giving guidance on determinants of physical function and how physical function can be examined in patients with axSpA.

Successful evaluation of spinal mobility measurements with the Epionics SPINE device in patients with axial spondyloarthritis compared to controls

OBJECTIVE

To evaluate ES for quantification of spinal mobility in patients with axSpA.

METHODS

A total of 153 individuals, 39 females and 114 males, were examined:134 axSpA patients, 40 non-(nr-) and 94 radiographic (r)-axSpA, and 19 healthy controls (HC), respectively. 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 axSpA patients and HC (all p<0.001) as well as between r- and nr-axSpA (p<0.01). In axSpA patients a negative correlation between ES and BASMI values was found: -0.76≤r≤-0.52 (p<0.05). BASFI 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 did almost 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 OMERACT criteria. RoK and RoM scores provide additional information on physical function of axSpA patients.

Validity and reliability of a sensor-based electronic spinal mobility index for axial spondyloarthritis

OBJECTIVE

To evaluate the validity and reliability of inertial measurement unit (IMU) sensors in the assessment of spinal mobility in axial spondyloarthritis (axSpA).

METHODS

A repeated measures study design involving 40 participants with axSpA was used. Pairs of IMU sensors were used to measure the maximum range of movement at the cervical (Cx) and lumbar (Lu) spine. A composite IMU score was defined by combining the IMU measures. Conventional metrology and physical function assessment were performed. Validation was assessed considering the agreement of IMU measures with conventional metrology and correlation with physical function. Reliability was assessed using intra-class correlation coefficients (ICCs).

RESULTS

The composite IMU score correlated closely (r = 0.88) with the BASMI. Conventional Cx rotation and lateral flexion tests correlated closely with IMU equivalents (r = 0.85, 0.84). All IMU movement tests correlated strongly with BASFI, while this was true for only some of the BASMI tests. The reliability of both conventional and IMU tests (except for chest expansion) ranged from good to excellent. Test-retest ICCs for individual conventional tests varied between 0.57 and 0.91, in comparison to a range from 0.74 to 0.98 for each of the IMU tests. Each of the composite regional IMU scores had excellent test-retest reliability (ICCs=0.94-0.97), comparable to the reliability of the BASMI (ICC=0.96).

CONCLUSION

Cx and Lu spinal mobility measured using wearable IMU sensors is a valid and reliable assessment in multiple planes (including rotation), in patients with a wide range of axSpA severity.

Role of Metrology in Axial Spondyloarthritis: Does It Provide Unique Information in Assessing Patients and Predicting Outcome? Results From the British Society for Rheumatology Biologic Register for Ankylosing Spondylitis

OBJECTIVE

To determine among patients with axial spondyloarthritis (SpA) the factors associated with decreased spinal mobility and to determine whether poor mobility is a predictor of response to anti-tumor necrosis factor (anti-TNF) therapy.

METHODS

This was a prospective UK cohort study of persons meeting Assessment of Spondylarthritis international Society (ASAS) criteria for axial SpA. At recruitment, clinical and patient-reported factors independently associated with spinal mobility (measured by the Bath Ankylosing Spondylitis Metrology Index [BASMI]) were determined. Among those commencing anti-TNF therapy, factors that were independent predictors of response were determined using ASAS criteria, quality of life, and Ankylosing Spondylitis Disease Activity Score (ASDAS) response criteria.

RESULTS

A total of 1,960 participants were eligible; 70% were male and the median age was 48 years (interquartile range [IQR] 37,59), median BASMI score 3.6 (IQR 2.2, 5.3). Factors independently associated with poor spinal mobility were poorer function, meeting radiographic criteria for AS, longer symptom duration, higher levels of inflammation (measured by C-reactive protein level), older age, male sex, not being currently employed, and lower levels of education. For 51% of participants, the measured BASMI score was within 1 of that estimated. Poorer mobility (higher BASMI score) was an independent predictor of not meeting response criteria for ASAS 20% improvement (odds ratio [OR] per increasing score 0.80 [IQR 0.66, 0.98]), ASAS 40% improvement (OR 0.69 [IQR 0.50, 0.95]), and quality of life (measured by the Ankylosing Spondylitis Quality of Life Questionnaire) (β = 0.64 [IQR 0.26, 1.02]), but was not related to meeting ASDAS response criteria.

CONCLUSION

The BASMI score was estimated moderately well by other routinely measured factors in patients with axial SpA and was an independent predictor of response to biologic therapy for some, but not all, commonly used measures. Consensus around its role in disease monitoring and clinical decisions, particularly in the likely context of face-to-face consultations becoming less frequent, remains to be established.