A Contemporary View of the Diagnosis of Osteoporosis in Patients With Axial Spondyloarthritis

Disease Activity and Bone Microarchitectural Phenotype in Patients With Axial Spondyloarthritis

Background

Axial spondyloarthritis (AxSpA) is a chronic rheumatic disease characterized by spine inflammation, abnormal bone growth, and paradoxically osteoporosis and vertebral fractures. The pathogenesis of skeletal deficits in this disease is poorly understood.

Purpose

We sought to evaluate volumetric bone mineral density (vBMD) and bone microarchitecture in patients with AxSpA and to identify disease-related factors associated with skeletal abnormalities.

Methods

We enrolled patients between 2018 and 2021 as part of a 2-year prospective study at a single institution investigating skeletal health and the skeletal effects of interleukin-17 (IL-17) treatment. Patients with AxSpA who met Assessment in SpondyloArthritis International Society (ASAS) classification criteria by X-ray or had evidence of active inflammation on magnetic resonance imaging suggestive of sacroiliitis were referred to the study by their rheumatologists. We excluded those with a history of fragility fracture, multiple myeloma, Cushing's disease, primary hyperparathyroidism, osteomalacia, untreated vitamin D deficiency, secondary osteoporosis, or other systemic rheumatic diseases, as well as use of oral steroids for 2 or more weeks in the 6 months prior or current use of hormone replacement therapy, current oral bisphosphonate, past or current intravenous bisphosphonate, teriparatide, or denosumab therapies. A total of 1606 patients were screened for eligibility. Of these, 30 participants were enrolled (mean age 43 years, 50% male). Patients with AxSpA had dual-energy X-ray absorptiometry (DXA) measurements of areal BMD (aBMD) and high-resolution peripheral quantitative computed tomography (HR-pQCT) measurements of vBMD microarchitecture and failure load by finite element analysis. Standardized disease assessment tools used included the Bath Ankylosing Spondylitis Disease Activity (BASDAI), Metrology Index (BASMI), and Functional Index (BASFI).

Results

In the 30 included patients, mean DXA and HR-pQCT Z-scores were within 1 standard deviation (SD) of normal for all indices, except for total vBMD in males (-1.2 SD below mean). Mean symptom duration was 11.7 years and mean scores for BASDAI, BASFI, and BASMI were 4.6, 3.6, and 2.7, respectively (range 1-10, 10 = severe limitation). Longer disease duration was associated with more severe skeletal deficits at the hip and tibia-specifically, lower hip aBMD, lower meta- and inner-trabecular vBMD, lower trabecular number, and higher trabecular separation and heterogeneity.

Conclusion

This study of 30 patients with AxSpA found that abnormalities in bone density and microarchitecture at weightbearing sites were associated with longer disease duration. Because of its small sample size, larger studies are needed to better characterize the pathogenic disease factors that govern skeletal damage in AxSpA.

Probability of the 10-year Risk of Hip and Major Osteoporotic Fracture in Non-radiographic Axial Spondyloarthritis

BACKGROUND

Fracture risk in non-radiographic spondyloarthritis is underestimated. A reliable tool such as the Fracture Risk Assessment tool (FRAX) may assess this risk probability. This study aimed to assess the fracture risk by the FRAX score in patients with nr-axSpA and to determine factors associated with high fracture risk.

METHODS

We conducted a retrospective study of nr-axSpA patients meeting the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for spondyloarthritis. All patients had Bone Mineral Density (BMD) by dual-energy X-ray absorptiometry (DEXA). The 10- year probability of major osteoporotic fracture (MOF) and hip fracture (HF) was calculated using the Fracture Risk Assessment Tool (FRAX).

RESULTS

Among 40 patients with nr-axSpA, 27 were women (67.5%). Their mean age was 43.7 ± 12.1 years. The mean disease duration was 3.15 ± 2.7 years. Eighteen patients (45%) had osteopenia, and 12 patients (30%) had osteoporosis. The median HF FRAX was 0% [0-1.2]. The median MOF FRAX was 0.5% [0.3-1.8]. MOF FRAX was positively correlated with age (p = 0.002), disease onset age (p = 0.006), disease duration (p = 0.024), and the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) (p < 0.0001), and negatively correlated with daily calcium intake (p < 0.0001). HF FRAX was positively correlated with mSASSS (p < 0.0001) and negatively correlated with daily calcium intake (p = 0.005).

CONCLUSION

Our study confirmed the frequency of bone loss during nr-axSpA and showed that osteoporotic risk fracture was related not only to traditional risk factors for osteoporosis but also to disease-related factors.

Osteoporosis in Rheumatology

Introduction

Osteoporosis is a common diagnosis and comorbidity observed in patients with rheumatic diseases. It is frequently associated with conditions such as rheumatoid arthritis, spondyloarthropathy, systemic lupus erythematosus, and other autoimmune rheumatic diseases.

Conclusion

The incidence of osteoporosis is influenced by factors such as uncontrolled disease, prolonged and higher doses of steroid use, immobility, advanced age, and postmenopausal status. Achieving good control of the underlying disease, minimizing or avoiding the use of steroids for extended periods, and ensuring adequate supplementation of vitamin D and calcium are crucial in reducing the incidence of osteoporosis. Regular screening and appropriate management of osteoporosis can significantly decrease the associated morbidity and mortality.

The association between comorbidities and disease activity in spondyloarthritis - A narrative review

Comorbidities, including cardiovascular disease, osteoporosis, and depression, are more prevalent in patients with spondyloarthritis (SpA) than in the general population. Clinical and laboratory markers of disease activity are associated with numerous of these comorbidities, and studies suggest that the treatment of SpA can have a positive impact on comorbidities; conversely, managing comorbidities can improve disease activity. Therefore, the screening of comorbidities is considered a core component of a rheumatology consultation, and treatment should be performed in liaison with other health professionals (e.g. general physicians). Validated tools and questionnaires can be used for not only the detection but also the monitoring of potential comorbidities. Understanding whether a comorbidity is a separate disease entity, linked to SpA or its treatment, or an extra-musculoskeletal manifestation of the disease is important to identify the most appropriate treatment options.

Association Between SPARC Polymorphisms and Ankylosing Spondylitis and Its mRNA and Protein Expression in a Chinese Han Population: A Case-Control Study

Objective

We explore the association of polymorphisms in Secreted protein acidic and rich in cysteine (SPARC) with ankylosing spondylitis (AS) and detect SPARC mRNA and protein expression in a Chinese Han population.

Methods

Nine single-nucleotide polymorphisms (SNPs) of SPARC were genotyped in 768 AS patients and 768 controls by TaqMan genotyping assay. mRNA expression of SPARC was detected by real-time polymerase chain reaction (RT-PCR), and serum level of SPARC protein was detected by ELISA.

Results

The frequency of A allele of rs171121187 was significantly higher in AS patients than in controls (Pc=0.003, odds ratio [OR]=1.45, 95% confidence interval [95% CI] = 1.18-1.77), the AA and AC genotypes increased the risk of AS when compared with CC genotype (Pc=0.003, OR=3.96, 95% CI=1.80-8.75, and Pc=0.003, OR=1.27, 95% CI=1.01-1.61, respectively). The frequency of G allele of rs4958487 was significantly lower in AS than in controls (Pc=0.001, OR=0.60, 95% CI=0.47-0.68), the GG and GA genotypes reduced the risk of AS when compared with AA genotype (Pc=0.005, OR=0.46, 95% CI 0.18-1.14, and Pc=0.005, OR=0.60, 95% CI=0.45-0.79, respectively). The haplotype AA of rs17112187/rs4958487 significantly increased the risk of AS (P=2.31E-5, OR=1.60, 95% CI=1.28-1.98), while haplotype CG decreased the risk of AS (P=5.42E-5, OR=0.55, 95% CI=0.41-0.74). Expression levels of SPARC mRNA were significantly lower in both Peripheral blood mononuclear cells (PBMC) and granulocytes in AS patients than in controls (P=0.008 and P=0.005, respectively). SPARC protein levels were also reduced in AS patients versus the controls (P=0.002).

Conclusion

This study indicates that polymorphisms in SPARC are associated with AS susceptibility, and both mRNA and protein levels of SPARC are decreased in AS patients in a Chinese Han population.

Low-dose CT hounsfield units: a reliable methodology for assessing vertebral bone density in radiographic axial spondyloarthritis

Objective

Studying vertebral bone loss in radiographic axial spondyloarthritis (r-axSpA) has been challenging due to ectopic bone formation. We cross-sectionally analysed low-dose CT (ldCT) trabecular bone density Hounsfield units (HU) measurements and calculated inter-reader reliability at the vertebral level in patients with r-axSpA.

Methods

LdCT scans of 50 patients with r-axSpA from the sensitive imaging in ankylosing spondylitis study, a multicentre 2-year prospective cohort were included. Trabecular bone HU taken from a region of interest at the centre of each vertebra (C3-L5) were independently assessed by two trained readers. HU mean (SD), and range were provided at the vertebral level, for each reader and centre separately. Inter-reader reliability and agreement were assessed using intraclass correlation coefficients (ICC; single measurements, absolute agreement, two-way mixed effects models); smallest detectable difference and Bland-Altman plots.

Results

Overall, 1100 vertebrae were assessed by each reader. HU values decreased from cranial to caudal vertebrae. For readers 1 and 2 respectively, the highest mean (SD) HU value was obtained at C3 (354(106) and 355(108)), and the lowest at L3 (153(65) and 150 (65)). Inter-reader reliability was excellent (ICC(2,1):0.89 to 1.00). SDD varied from 4 to 8. For most vertebrae, reader 1 scored somewhat higher than reader 2 (mean difference of scores ranging from −0.6 to 2.9 HU). Bland-Altman plots showed homoscedasticity.

Conclusion

LdCT measurement of HU is a feasible method to assess vertebral bone density in r-axSpA with excellent inter-reader reliability from C3 to L5. These results warrant further validation and longitudinal assessment of reliability.

Effects of Biological/Targeted Therapies on Bone Mineral Density in Inflammatory Arthritis

Inflammatory arthritis has been reported to be associated with the development of osteoporosis. Recent research has investigated the mechanisms of bone metabolism in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Progress in both animal and clinical studies has provided a better understanding of the osteoclastogenesis-related pathways regarding the receptor activator of nuclear factor-κB ligand (RANKL), anti-citrullinated protein antibodies (ACPAs), and Wnt signaling and Dickkopf-related protein 1 (Dkk-1). The complex interplay between inflammatory cytokines and bone destruction has been elucidated, especially that in the interleukin-17/23 (IL-17/23) axis and Janus kinase and signal transducer and activator of transcription (JAK-STAT) signaling. Moreover, advances in biological and targeted therapies have achieved essential modifications to the bone metabolism of these inflammatory arthritis types. In this narrative review, we discuss recent findings on the pathogenic effects on bone in RA and SpA. Proinflammatory cytokines, autoantibodies, and multiple signaling pathways play an essential role in bone destruction in RA and SpA patients. We also reviewed the underlying pathomechanisms of bone structure in biological and targeted therapies of RA and SpA. The clinical implications of tumor necrosis factor inhibitors, abatacept, rituximab, tocilizumab, Janus kinase inhibitors, and inhibitors of the IL-17/23 axis are discussed. Since these novel therapeutics provide new options for disease improvement and symptom control in patients with RA and SpA, further rigorous evidence is warranted to provide a clinical reference for physicians and patients.

Bone Involvement in Patients with Spondyloarthropathies

Spondyloarthropathies (SpA) are common systemic inflammatory rheumatic diseases, in which, as in other rheumatic diseases, levels of markers of bone resorption are elevated, leading to bone loss and elevated risk of vertebral fractures. However, the diseases are also associated with new bone formation in the spine, the so-called syndesmophytes. We tried to unravel the pathogenesis of formation and growth of syndesmophytes and evaluated new diagnostic and treatment options. After a successful meeting of the Working Group on Rheumatic Diseases at the ECTS 2020, we (WL and CR) were excited about the quality of the speakers (CM, JH, AG, and GL) and their complimentary lectures. Given the relative lack of reviews on spondyloarthropathies and bone, we decided to work together on a comprehensive review that might be interesting for basic scientists and clinically relevant for clinicians. Radiographic progression in axSpA is linked to several risk factors, like male sex, smoking, HLA-B-27, increased levels of CRP, presence of syndesmophytes, and marked inflammation on MRI. The potential role of mechanical stress in the context of physically demanding jobs has been also suggested to promote structural damages. Different treatment options from NSAIDs to biologic agents like TNF inhibitors (TNFi) or IL-17inhibitors (IL-17i) result in a reduction of inflammation and symptoms. However, all these different treatment options failed to show clear and reproducible results on inhibition on syndesmophyte formation. The majority of data are available on TNFi, and some studies suggested an effect in subgroups of patients with ankylosing spondylitis. Less information is available on NSAIDs and IL-17i. Since IL-17i have been introduced quite recently, more studies are expected. IL-17 inhibitors (Il-17i) potently reduce signs and symptoms, but serum level of IL-17 is not elevated, therefore, IL-17 probably has mainly a local effect. The failure of anti-IL-23 in axSpA suggests that IL-17A production could be independent from IL-23. It may be upregulated by TNFα, resulting in lower expression of DKK1 and RANKL and an increase in osteogenesis. In active AS markers of bone resorption are increased, while bone formation markers can be increased or decreased. Bone Turnover markers and additional markers related to Wnt such as DKK1, sclerostin, and RANKL are valuable for elucidating bone metabolism on a group level and they are not (yet) able to predict individual patient outcomes. The gold standard for detection of structural lesions in clinical practice is the use of conventional radiographics. However, the resolution is low compared to the change over time and the interval for detecting changes are 2 years or more. Modern techniques offer substantial advantages such as the early detection of bone marrow edema with MRI, the fivefold increased detection rate of new or growing syndesmophytes with low-dose CT, and the decrease in 18F-fluoride uptake during treatment with TNFα-inhibitors (TNFi) in a pilot study in 12 AS patients. Detection of bone involvement by new techniques, such as low-dose CT, MRI and 18-Fluoride PET-scans, and bone turnover markers, in combination with focusing on high-risk groups such as patients with early disease, elevated CRP, syndesmophytes at baseline, male patients and patients with HLA-B27 + are promising options for the near future. However, for optimal prevention of formation of syndesmophytes we need more detailed insight in the pathogenesis of bone formation in axSpA and probably more targeted therapies.

The applicability of trabecular bone score for osteoporosis diagnosis in ankylosing spondylitis

Ankylosing spondylitis (AS) patients have a high risk of osteoporotic fractures. The aim of this study was to evaluate the usefulness of trabecular bone score (TBS) in assessing fracture risk in patients with AS. 67 patients meeting the ASAS classification criteria were enrolled in the study. Fracture risk for each patient was assessed based on a lumbar spine exam encompassing bone mineral density (BMD), and TBS through a dual-energy X-ray absorptiometry (DXA) exam. In addition, each patient had an X-ray taken of their lumbar and thoracic spine to determine the presence of syndesmophytes and bony bridges, as well as spinous process and vertebral body fractures. Moreover, each patient's medical history was analyzed for other osteoporotic fractures. A major osteoporosis fracture (MOF) was found in 11 (16%) patients in total, of which 7 (10%) were vertebral body fractures. The mean TBS in patients with MOF and no MOF were, respectively, 1.12 and 1.29 (p < 0.001). No significant differences were found in BMD scores between the two groups. Syndesmophytes and bony bridges occurred more frequently in patients with MOF (p = 0.02). Age of 50 or more (RR = 9.86, p = 0.002), TBS score ≤ 1.31 (RR = 2.07, p < 0.0001), and presence of syndesmophytes and bony bridges (RR = 2.14, p = 0.04) were considered a relative risk (RR) increasing factors. TBS is a markedly more sensitive method of identifying patients with a high fracture risk compared to BMD measurement in a DXA exam in patients with AS.