The genetic backbone of ankylosing spondylitis: how knowledge of genetic susceptibility informs our understanding and management of disease.

Ankylosing spondylitis (AS) is a seronegative, chronic inflammatory arthritis with high genetic burden. A strong association with HLA-B27 has long been established, but to date its contribution to disease aetiology remains unresolved. Recent insights through genome wide studies reveal an increasing array of immunogenetic risk variants extraneous to the HLA complex in AS cohorts. These genetic traits build a complex profile of disease causality, highlighting several molecular pathways associated with the condition. This and other evidence strongly implicates T-cell-driven pathology, revolving around the T helper 17 cell subset as an important contributor to disease. This prominence of the T helper 17 cell subset has presented the opportunity for therapeutic intervention through inhibition of interleukins 17 and 23 which drive T helper 17 activity. While targeting of interleukin 17 has proven effective, this success has not been replicated with interleukin 23 inhibition in AS patients. Evidence points to significant genetic diversity between AS patients which may, in part, explain the observed refractoriness among a proportion of patients. In this review we discuss the impact of genetics on our understanding of AS and its relationship with closely linked pathologies. We further explore how genetics can be used in the development of therapeutics and as a tool to assist in the diagnosis and management of patients. This evidence indicates that genetic profiling should play a role in the clinician's choice of therapy as part of a precision medicine strategy towards disease management.

Advances in treatment of axial spondyloarthritis are associated with improved patient outcomes: data from the Ankylosing Spondylitis Registry of Ireland (ASRI).

The Ankylosing Spondylitis Registry of Ireland (ASRI) captures both radiographic and non-radiographic axial spondyloarthritis (axSpA) in a large, well characterised cohort. This is a valuable resource for studies in therapeutics and burden of disease, following a period of rapid change in the field of axSpA. This study aims to perform a focused analysis on patient outcomes and pattern of medication usage in axSpA. This is a cross-sectional study of registry data on 885 patients with confirmed axSpA as per the ASAS criteria for axSpA, as diagnosed by a Rheumatologist. Analysis was performed using IBM SPSS version 26. Patients were analysed on the basis of treatment categorised as: no medication, NSAIDs, biologics or combination therapy. Statistical significance was indicated by p value of < 0.05. Currently 885 patients are enrolled in the ASRI, made up of 72.5% (642) males and 26.9% (238) females. The majority of the cohort was categorized as radiographic axSpA 78.3% (693), with 21.7% (192) meeting criteria for non-radiographic disease. Overall 40.6% (359) reported at least one comorbidity. Older age was associated with no medications compared to those on biologic therapy (50.3 vs 45, p = 0.01). Lower levels of disease activity and higher quality of life were noted in those on biologics as compared to NSAIDs alone. This analysis provides detailed epidemiological data on axSpA from a large national registry. These results detail significant differences in prescribing patterns and impact on patient outcomes in axSpA. Ongoing development of registries provides a valuable insight into the real-world effects of axSpA.

Pharmacological treatment for managing bone health in axial spondyloarthropathy: systematic review and meta-analysis.

Axial spondyloarthropathy (axSpA) is associated with an increased prevalence of osteoporosis, but no recommendations exist to guide management. This systematic review and meta-analysis aim to assess the efficacy of pharmacological and non-pharmacological interventions on bone mineral density (BMD) in axSpA. Electronic databases were searched from inception to June 2019 for randomised controlled trials (RCTs) and quasi (q)-RCTs with pharmacological and non-pharmacological interventions. Independent reviewers undertook screening, and risk of bias and quality assessments. Primary outcomes of interest were BMD at spine and hip. Eight studies (two RCTs and six qRCTs) were included (602 participants). Moderate level evidence favoured alendronate over placebo at femoral neck [mean difference (MD) 2.01, 95% CI 0.67 to 3.35], but there was low-level evidence showing no effect at the spine. There was moderate level evidence showing no effect of tumour necrosis factor inhibitors (TNFi) on BMD at total hip (MD - 0.01, 95% CI - 0.06 to 0.04). Very low-level evidence demonstrated no effect of TNFi on spine or femoral neck. Moderate level evidence favoured neridronate over infliximab at the spine (MD 3.26, 95% CI 1.14 to 5.38), but low-level evidence showed no effect at the total hip (MD 2.75, 95% CI - 0.21 to 5.71). There were no eligible studies investigating the efficacy of non-pharmacological interventions. We conditionally recommend alendronate for management of low BMD in axSpA. The balance of evidence does not recommend the use of TNF-inhibitors for treating low BMD. There is a lack of high-quality evidence guiding clinicians treating osteoporosis in axSpA.

Physical activity in spondyloarthritis: a systematic review.

Physical activity (PA) is associated with numerous health-related benefits among adults with chronic diseases and the general population. As the benefits are dose-dependent, this review aims to establish the PA levels of adults with spondyloarthritis and to compare these to the general population. Electronic databases (Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE/PubMed, PEDro, AMED, CINAHL) were systematically searched from inception to May 2014 using medical subject headings and keywords. This was supplemented by searching conference abstracts and hand-searching reference lists of included studies. Eligible studies were randomized controlled trials and observational studies of adults with SpA in which free-living PA or energy expenditure levels were measured. Subjects less than 18 years or with juvenile-onset SpA were excluded. Outcomes included objective and self-report measurements. Two reviewers independently screened studies for inclusion and assessed methodological quality using the Cochrane risk of bias tool and the RTI item bank. From the 2,431 records reviewed, nine studies involving 2,972 participants were included. This review focused on qualitative synthesis. Meta-analyses were not undertaken due to differences in study design, measurement tools, and participant characteristics. This heterogeneity, coupled with the risk of bias inherent in the included observational studies, limits the generalizability of findings. Objective measurements suggest PA levels may be lower among adults with spondyloarthritis than in healthy population controls. Self-reported PA and self-reported rates of adherence to PA recommendations varied largely across studies; higher disease activity was associated with lower self-reported PA levels. Physical activity levels may be lower in adults with axial spondyloarthritis, with higher disease activity associated with lower PA levels.

Decreased physical activity and cardiorespiratory fitness in adults with ankylosing spondylitis: a cross-sectional controlled study.

The health benefits of physical activity (PA) in the general population are numerous; however, few studies have measured PA among adults with ankylosing spondylitis (AS). The aims of this study were to: (1) objectively measure the PA levels and cardiorespiratory fitness of adults with AS and compare these to population controls, and (2) examine the relationships between PA, cardiorespiratory function and condition-specific outcomes. This cross-sectional study included participants (>18 years) meeting the modified New York criteria for AS, and matched population controls. Exclusion criteria were the presence of comorbidities limiting PA, or recent changes in medication usage. Participants completed clinical questionnaires assessing disease activity, physical function and quality of life. Tri-axial accelerometers recorded habitual PA over 1 week. Cardiorespiratory fitness was assessed by submaximal treadmill test with breath-by-breath gas analysis and heart rate monitoring. Thirty-nine adults with AS and 39 controls were recruited. The AS group spent significantly less time performing vigorous-intensity PA than controls [mean difference (95 % CI) 1.8 min/day (1.2-2.7)] and performed significantly fewer bouts of health-enhancing PA [1.7 min/day (1.1-2.5)]. The AS group had significantly lower predicted VO(2MAX) than controls [6.0 mL kg(-1) min(-1) (1.8-10.1)]. PA was associated with aerobic capacity. Sedentary time was associated with disease activity and physical function. Adults with AS participate in less health-enhancing PA than population controls. Fewer than half meet PA recommendations, despite exercise being a key component of AS management. Explorations of PA behaviour and strategies to increase PA participation are needed.

Physical activity guidelines: is the message getting through to adults with rheumatic conditions?

OBJECTIVES: This study examines the awareness and self-report knowledge of physical activity (PA) guidelines among adults with rheumatic conditions and evaluates rates of adherence to PA recommendations. Secondary aims include (i) investigating perceived benefits and barriers to exercise and (ii) exploring correlates associated with PA. METHODS: This cross-sectional study involved adults attending an outpatient rheumatology clinic completing a questionnaire. Closed- and open-ended questions enquired about awareness and knowledge of PA guidelines, and a single-item self-report measure of PA was included. Perceptions of exercise were assessed using the Exercise Benefits and Barriers Scale. Descriptive statistics described participant characteristics and age-adjusted bivariate analyses explored associations between socio-demographic and condition-related factors and PA. RESULTS: A total of 401 adults (134 males, 267 females) completed the questionnaire. Only 17.6% of respondents were aware of national PA guidelines and 17.4% accurately identified the frequency and duration of the recommendations. A quarter of respondents (26.7%) reported adherence to the guidelines, while 30.5% reported no weekly PA. Higher perceived benefits and lower perceived barriers to exercise were positively associated with PA behaviour. CONCLUSION: A large majority of respondents were not aware of PA guidelines and self-report knowledge of PA recommendations was largely inaccurate. Despite the role of PA in health promotion and in the management of rheumatic conditions, adherence to PA recommendations was low. Level of education, perceived benefits and barriers to exercise, and awareness and self-report knowledge of PA guidelines are associated with PA behaviour.

Exercise therapy for spondyloarthritis: a systematic review.

To evaluate the effects of therapeutic exercise on pain, stiffness, quality of life, physical function, disease activity, health-related fitness and cardiovascular risk factors in adults with spondyloarthritis (SpA). Electronic databases (Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE/PubMed, PEDro, AMED, CINAHL) were systematically searched from inception to October 2013 using medical subject headings and keywords. This was supplemented by searching conference abstracts and a hand search of reference lists of included studies. Randomised and quasi-randomised studies of adults with SpA in which at least one of the comparison groups received an exercise intervention were included. Outcomes of interest were pain, stiffness, quality of life, physical function and disease activity. Secondary outcomes were health-related fitness and cardiovascular risk factors. Two reviewers independently screened studies for inclusion. Methodological quality was assessed by two reviewers using the Cochrane risk of bias tool and the PEDro scale. Twenty-four studies, involving 1,498 participants, were included. Meta-analyses were not undertaken due to clinical heterogeneity, and this review focuses on qualitative synthesis. Moderate evidence supports exercise interventions in improving physical function, disease activity and chest expansion compared to controls; there is low-level evidence of improved pain, stiffness, spinal mobility and cardiorespiratory function. Supervised group exercise yields better outcomes than unsupervised home exercise. The addition of aerobic components to flexibility programmes improves cardiorespiratory outcomes, but not cardiovascular risk factors. The most effective exercise protocol remains unclear. Current evidence suggests that therapeutic exercises are beneficial for adults with ankylosing spondylitis; effects on other SpA subtypes are unknown.

Characteristics and burden of disease in patients with radiographic versus non-radiographic axial spondyloarthritis in the ASRI cohort.

BACKGROUND: Axial spondyloarthritis (axSpA) comprises patients with both radiographic and non-radiographic features. Previous studies have shown similar burden of disease between these two groups. AIMS: The Ankylosing Spondylitis Registry of Ireland (ASRI) was formed with the objective to measure the burden of axial spondyloarthritis in the population and identify early predictors of a poor outcome. For this analysis, the ASRI database was used to compare the characteristics and burden of disease in patients with radiographic versus non-radiographic axial spondyloarthritis. METHODS: Patients with radiographic axial spondyloarthritis (r-axSpA) were defined as those with X-ray evidence of sacroiliitis. Patients with non-radiographic axial spondyloarthritis (nr-axSpA) were defined as having MRI evidence of sacroiliitis but no X-ray evidence of sacroiliitis. RESULTS: In total, 764 patients were included. Analysis of radiographic status showed 88.1% (n = 673) of patients with r-axSpA and 11.9% (n = 91) with nr-axSpA (Table 1). Patients with nr-axSpA were younger (41.3 vs. 46.6 years, p < 0.01), had shorter disease duration (14.8 vs. 20.2 years, p < 0.01) and had lower proportion of males (66.6% vs. 78.4%, p = 0.02) with lower frequency of HLA-B27 positivity (73.6% vs. 90.5%, p < 0.01). The nr-axSpA group had lower BASDAI (3.37 vs. 4.05, p = 0.01), BASFI (2.46 vs. 3.88, p < 0.01), BASMI (2.33 vs. 4.34, p < 0.01), ASQoL (5.2 vs. 6.67, p = 0.02) and HAQ scores (0.38 vs. 0.57, p < 0.01). There were no significant differences in the prevalence of extra-musculoskeletal manifestations or use of medications. CONCLUSIONS: This study provides evidence to suggest that the burden of disease is less in patients with non-radiographic axial spondyloarthritis than radiographic axial spondyloarthritis.

Radiographic severity of ankylosing spondylitis is associated with polymorphism of the large multifunctional peptidase 2 gene in the Spondyloarthritis Research Consortium of Canada cohort.

OBJECTIVE: There are limited data on genetic predictors of radiographic progression. The aim of this study was to examine polymorphisms in genes involved in antigen presentation and their effect on radiographic severity and progression. METHODS: Caucasian patients with ankylosing spondylitis (AS) (diagnosed according to the modified New York criteria) from 2 Canadian centers were enrolled. Patients in the progression part of the study had at least 2 sets of radiographs obtained at a minimum gap of 1.5 years, with a modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Peripheral blood DNA was used for genotyping a panel of 13 coding-region single-nucleotide polymorphisms (SNPs) in ERAP1, LMP2, LMP7, TAP1, and TAP2. Linear regression analysis was performed to identify the predictors of the baseline mSASSS and logistic regression for predictors of progression. Progression was defined as an increase of 1 mSASSS unit per year. RESULTS: A total of 241 AS patients (81% males; 82% HLA-B27-positive) were enrolled from the 2 centers for analysis of the predictors of baseline radiographic severity. In univariate analyses, the baseline mSASSS was associated with sex, disease duration, and SNPs rs30187 (ERAP1) and rs17587 (LMP2). In multivariate analyses, duration of disease (B = 0.74; P = 1 × 10(-11) ), sex (B = 12.1; P = 5 × 10(-5) ), and the LMP2 SNP rs17587 (B = 6.2; P = 0.01) were significantly associated with the baseline mSASSS. In multivariate analyses of progression, only the baseline mSASSS was a significant predictor (B = 0.03; P = 0.003). CONCLUSION: This is the first study to demonstrate that LMP2 variants can affect radiographic severity in AS. The baseline mSASSS remains the strongest predictor of radiographic progression but explains only a fraction of the variability seen.

The Lingering Health Challenge: Addressing Obesity in Axial Spondyloarthritis.

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that primarily affects the axial skeleton, including the spine and sacroiliac joints.1 It encompasses both nonradiographic axSpA (nr-axSpA) and radiographic axSpA (also known as ankylosing spondylitis [AS]), the latter characterized by radiographic evidence of sacroiliitis.2.

Structural disease modification in axial spondyloarthritis.

"Disease modification" in axial spondyloarthritis (axSpA) seeks to not only alleviate clinical symptoms but also alter the disease's natural course by impeding new bone formation. Recent years have witnessed the effectiveness of treatments, including biologics and nonsteroidal anti-inflammatory drugs, in managing axSpA symptoms. Emerging evidence points toward their potential impact on slowing structural disease progression. This comprehensive review centers on the pivotal role of inhibiting new bone formation in axSpA disease modification. It delves into the significance of imaging techniques for assessing disease progression and explores the disease-modifying properties of available axSpA treatments, encompassing NSAIDs, TNF inhibitors, IL-17 inhibitors, and JAK inhibitors. This article offers valuable insights into the evolving landscape of disease modification strategies in axial spondyloarthritis, highlighting the multifaceted approaches used to attain these objectives.

Testing the feasibility and acceptability of an online 'Fatigue and Activity Management Education for Work (FAME-W) programme' for individuals with inflammatory arthritis.

INTRODUCTION: Fatigue and Activity Management Education for Work (FAME-W) is a four-week, occupational therapy led programme focussing on fatigue management strategies. FAME-W was designed to be delivered in person; however, due to COVID-19 pandemic it was modified to be an online group-based self-management intervention. The purpose of this study was to test the feasibility and acceptability of the online delivery format of FAME-W. METHODS: This was a mixed methods study. Participants were randomly allocated to intervention or control group. Participants in the intervention group received a four-week online FAME-W. The control group participants received a FAME-W handbook. Participants were required to complete questionnaires on work presenteeism, fatigue, mood, Health Related Quality of Life and pain at baseline, and 3 months post-intervention. Participants in the intervention group attended a focus group immediately following the completion of the programme and the control group participated in individual interviews. RESULTS: Seven of ten individuals recruited participated in the study. Majority of participants had Rheumatoid Arthritis and were working full-time. The mean age of intervention participants was 53 ± 10.4 and 56.5 ± 3.7 for the controls. All participants in the intervention group had 100% attendance, completed all study measures and activities. Participants had positive comments about the programme format, content, and delivery. Improvements were observed in most measures at follow up. CONCLUSION: Results suggest that an online programme to improve work ability was feasible and acceptable to individuals with inflammatory arthritis. The online delivery format was favoured over attending a centre-based programme. The findings support a definitive intervention trial of online FAME-W.

Central Obesity in Axial Spondyloarthritis: The Missing Link to Understanding Worse Outcomes in Women?

OBJECTIVE: To determine (1) the prevalence of central obesity in axial spondyloarthritis (axSpA) and its effect on disease-related outcomes and (2) how this differs between sexes. METHODS: Data were extracted from the Ankylosing Spondylitis Registry of Ireland. Patients with physical measurements for the calculation of anthropometric measures were included. BMI and waist-to-hip ratio (WHR) were used to compare classifications of obesity. Comparison analyses based on sex and central obesity were carried out. Multivariate analysis examined the effects of these factors on the following patient-reported outcomes: the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Functional Index (BASFI), the Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire, and the Health Assessment Questionnaire (HAQ). RESULTS: In total, 753 patients were included in the analysis. Of these patients, 29.6% (n = 223) were classified as obese based on their BMI, and 41.3% (n = 311) were classified as centrally obese according to the WHR. The prevalence of central obesity was significantly higher among women with axSpA compared to men (71.6% vs 29.9%, P < 0.01). Central obesity had a clear effect on patient outcomes, regardless of sex. Presence of central obesity was associated with significantly worse BASFI scores (P < 0.01), HAQ scores (P < 0.01), and ASQoL questionnaire scores (P = 0.01), with a nonsignificant trend toward worse BASDAI scores (P = 0.07). CONCLUSION: There was a high prevalence of central obesity as assessed by the WHR in axSpA, most notably among women with axSpA. This modifiable comorbidity was significantly associated with worse quality of life, greater impairment of functional ability, and a trend toward worse disease activity. Regular use of the WHR to screen for central obesity as part of an axSpA assessment would provide an opportunity for prompt identification and intervention for at-risk patients.

Tender to touch-Prevalence and impact of concomitant fibromyalgia and enthesitis in spondyloarthritis: An ancillary analysis of the ASAS PerSpA study.

OBJECTIVES: The primary objective was to evaluate the co-existence of fibromyalgia (FM) & enthesitis in individuals with spondyloarthritis (SpA). Secondary objectives were to identify clinical features associated with the presence of FM in enthesitis and analyse sex-specific differences. METHODS: This was an ancillary analysis of the Assessment of SpondyloArthritis International Society Peripheral Involvement in SpA (PerSpA) study. Enthesitis was defined as the presence of enthesitis ever. Clinical FM was defined as the rheumatologist's confirmation of the presence of FM. A score of≥5/6 on the Fibromyalgia Rapid Screening Test (FiRST) defined a positive screening test for FM. RESULTS: Enthesitis ever and FM (EFM) co-existed in 10.3% (n=425) of the cohort using FiRST criteria and 5.3% using clinical diagnosis of FM. More individuals with FM by clinical diagnosis had imaging-confirmed enthesitis ever than by FiRST criteria. More females had EFM than males, defined clinically (76.9% vs 23.1%) or by FiRST criteria (62.6% vs 37.4%). Individuals with EFM had more severe disease across all measures compared to those with enthesitis only, with no significant difference between sexes. EFM was significantly associated with age, female sex, BMI, BASDAI and region. CONCLUSION: FM is an important comorbidity in the setting of enthesitis in SpA. While EFM is more common in females, it is not a rare condition in males. EFM is associated with worse disease severity measures in SpA in both males and females. Recognition of FM in the setting of enthesitis is essential to prevent overtreatment and optimise patient outcomes.

What to expect when women with axial spondyloarthritis are expecting: Prevalence of complications of pregnancies in women with axial spondyloarthritis.

BACKGROUND: Understanding of axSpA is evolving rapidly. Unfortunately, for women with axSpA there is limited data available on pregnancy complications. The Ankylosing Spondylitis Registry of Ireland (ASRI) is a source of epidemiological data on axSpA in Ireland. The aim of this study was to examine the prevalence of pregnancy and fetal complications in axSpA women. METHODS: The ASRI records cross-sectional information on demographics, imaging, treatment, and patient outcomes. A dedicated section collects data on pregnancy, fertility and breastfeeding. For each axSpA woman, data on all pregnancies was recorded. Results were compared to global reference norms (GRN). All patients were diagnosed with axSpA by a Rheumatologist and met the ASAS classification criteria. Informed consent was obtained from all patients, with ethical approval obtained from local hospital ethics committees. RESULTS: Data was available on 98 women with axSpA. There were 335 pregnancies resulting in 279 live births. Of these pregnancies 51.6% (173) were uncomplicated and 48.5% (162) were complicated, with 13.1% (44) encountering multiple complications. Preterm birth (12.5 % vs 5.2%, p<0.01) and preeclampsia (6.8 % vs 2.8%, p<0.01) were more prevalent in axSpA pregnancies than GRN. Low birth weight was more prevalent in axSpA pregnancies (8.2 % vs 2.9%, p<0.01), however small for gestational age was less prevalent (5.4 % vs 11%, p<0.01). CONCLUSIONS: Preterm birth, preeclampsia and low birth weight are significantly more prevalent in pregnancies of axSpA women. Furthermore, there is a high prevalence of complications in axSpA pregnancies overall. These results provide essential insight into the impact of axSpA in pregnancy and call for further research to understand the pathogenesis of these complications.

Social isolation due to the COVID-19 pandemic has led to worse outcomes in females with inflammatory arthritis.

BACKGROUND: Prolonged social isolation as a result of the COVID-19 global pandemic has been a source of considerable psychological distress for many people. This can manifest in many ways and if left undetected can impact negatively on general health. It is essential to understand the impact of these conditions on inflammatory arthritis (IA) patients, especially axial spondyloarthropathy (axSpA). AIM: To capture the level of psychological distress for patients with IA following prolonged social isolation. METHODS: A survey was sent out to patients with a confirmed diagnosis of IA. This captured changes in sleep, mood, disease activity, employment and general health since the beginning of the social isolation period. A PHQ-4 (Patient Health Questionnaire) was included to determine level of psychological distress. RESULTS: Females with IA reported significantly higher rates of decline in general health (40% vs 16%, p = 0.01), mood disturbance (43.4% vs 26%, p = 0.03) and increased disease activity (50% vs 16%, p = 0.01) compared to males. Evaluating the mean PHQ-4 scores, no significant difference was noted between genders (4.80 vs 3.44, p = 0.10). However, females demonstrated a non-significant trend toward increased rates of moderate to severe psychological distress (40% vs 30%, p = 0.13). Subanalysis of patients with axSpA found high rates of moderate to severe distress in both genders. CONCLUSIONS: Females with IA reported significantly higher rates of decline in general health, mood disturbance and increased disease activity during the period of social isolation. This was reflected in a trend towards greater levels of psychological distress.

Measuring Spinal Mobility Using an Inertial Measurement Unit System: A Reliability Study in Axial Spondyloarthritis.

The objectives of this study were to evaluate the reliability of wearable inertial motion unit (IMU) sensors in measuring spinal range of motion under supervised and unsupervised conditions in both laboratory and ambulatory settings. A secondary aim of the study was to evaluate the reliability of composite IMU metrology scores (IMU-ASMI (Amb)). Forty people with axSpA participated in this clinical measurement study. Participant spinal mobility was assessed by conventional metrology (Bath Ankylosing Spondylitis Metrology Index, linear version-BASMILin) and by a wireless IMU sensor-based system which measured lumbar flexion-extension, lateral flexion and rotation. Each sensor-based movement test was converted to a normalized index and used to calculate IMU-ASMI (Amb) scores. Test-retest reliability was evaluated using intra-class correlation coefficients (ICC). There was good to excellent agreement for all spinal range of movements (ICC > 0.85) and IMU-ASMI (Amb) scores (ICC > 0.87) across all conditions. Correlations between IMU-ASMI (Amb) scores and conventional metrology were strong (Pearson correlation ≥ 0.85). An IMU sensor-based system is a reliable way of measuring spinal lumbar mobility in axSpA under supervised and unsupervised conditions. While not a replacement for established clinical measures, composite IMU-ASMI (Amb) scores may be reliably used as a proxy measure of spinal mobility.