Trabecular bone score as an assessment tool to identify the risk of osteoporosis in axial spondyloarthritis: a case-control study

Association of trabecular bone score with disease parameters and vertebral fractures in axial spondyloarthritis

Objectives

We aimed to study trabecular bone score (TBS) association with disease parameters and vertebral fractures (VFs) in patients with axial spondyloarthritis.

Methods

Patients diagnosed with axial spondyloarthritis were included in this cross-sectional study. Dual-energy X-ray absorptiometry was used to measure BMD in the lumbar spine and TBS. Low TBS was defined as ≤1.31. The association between TBS and disease parameters including Ankylosing Spondylitis Disease Activity Score (ASDAS), BASDAI, BASFI and BASMI was studied using logistic regressions.

Results

Our study included 56 patients, with a mean age of 38.9 ± 13.5 years and a mean disease duration of 12.7 ± 7.7 years. Patients with low TBS were significantly older and had higher waist circumference and body mass index. These patients also showed greater clinical activity, as evidenced by higher ASDAS-CRP, BASFI and BASMI scores (P < 0.05). In multivariate logistic regression, low TBS was associated with all disease parameters, except for BASMI: BASDAI (OR [95% CI] = 3.68 [1.48-9.19], P = 0.005), ASDAS-CRP (OR [95% CI] = 2.92 [1.20-7.10], P = 0.018), BASFI (OR [95% CI] = 1.04 [1.01-1.08], P = 0.018), BASMI (OR [95% CI] = 1.36 [0.99-1.87], P = 0.062). However, no association was observed between TBS and VFs.

Conclusion

TBS was associated with active spondyloarthritis, suggesting increased bone fragility in these patients. However, TBS failed to demonstrate an association with VFs.

The sacroiliac joint: An original and highly sensitive tool to highlight altered bone phenotype in murine models of skeletal disorders

Bone disorders may affect the skeleton in different ways, some bones being very impaired and others less severely. In translational studies using murine models of human skeletal diseases, the bone phenotype is mainly evaluated at the distal femur or proximal tibia. The sacroiliac joint (SIJ), which connects the spine to the pelvis, is involved in the balanced transfer of mechanical energy from the lumbar spine to the lower extremities. Because of its role in biomechanical stress, the SIJ is a region of particular interest in various bone diseases. Here we aimed to characterize the SIJ in several murine models to develop a highly reliable tool for studying skeletal disorders. We performed a 12-month in vivo micro-computed tomography (micro-CT) follow-up to characterize the SIJ in wild-type (WT) C57BL/J6 mice and compared the bone microarchitecture of the SIJ and the distal femur at 3 months by micro-CT and histology. To test the sensitivity of our methodology, the SIJ and distal femur were evaluated at 3 and 6 months, in 2 murine models of skeletal disorder, X-linked hypophosphatemia (Hyp mice) and HLA-B27 transgenic mice and compared to WT mice. A multimodal analysis was performed, using a combination of microCT and histological analysis. With the Hyp model, the SIJ displayed more bone microarchitecture alterations than the distal femur. Hyp mice showed a significant reduction in trabecular bone at both the distal femur and sacral slope as compared with WT mice, with a significant positive correlation between trabecular bone parameters of the distal femur and sacral side of the SIJ. Furthermore, trabecular bone parameters (Bone Volume/Total Volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), trabecular pattern factor (Tb.Pf)) were significantly increased compared to femoral parameters at the SIJ. The sacral articular cortical bone, which is indicative of osteoarticular lesions, was altered in Hyp mice. Interestingly, in accordance to previous studies, HLA-B27 transgenic mice did not show any osteoarticular lesions as compared with WT mice. Cortical bone parameters (thickness, porosity), as well as scoring performed with double blinding, did not show difference between the 2 genotypes. The characterization and evaluation of the SIJ surface appears very sensitive to emphasize alterations of bone and joint. The SIJ may represent a valuable tool to investigate both bone and local osteoarticular alterations in murine models of skeletal disorders and might be a relevant site for assessing the response to treatment of chronic bone diseases.

[Trabecular bone score in rheumatology : Are there benefits in comparison to bone densitometry alone?]

Patients with inflammatory rheumatic diseases have an increased risk of fractures due to the inflammatory potential of the disease and also because of the treatment with glucocorticoids that is often necessary. According to the current guidelines of the Governing Body on Osteology (DVO), the fracture risk can be assessed using dual energy X‑ray absorptiometry and can also be supplemented by measuring the trabecular bone score (TBS). The assessment of the TBS offers additional advantages, for example in glucocorticoid-induced osteoporosis and in patients with osteoproliferative changes of the spine (spondylarthritis) and thus optimizes the fracture risk assessment in the rheumatological patient population.

Prevalence of low trabecular bone score and its association with disease severity and activity in patients with axial spondyloarthritis

Axial spondyloarthritis (axSpA) increases the risk of osteoporosis and vertebral fractures. Bone mineral density (BMD) measured by dual X-ray absorptiometry (DXA) has limitations in axSpA patients. Trabecular bone score (TBS) indirectly assesses bone microarchitecture and can be used to predict fracture risk. However, few studies have investigated the role of TBS in axSpA patients. The objective of this study were to compare TBS between axSpA patients and 1:1 sex- and age-matched healthy volunteers and determine factors associated with low TBS in axSpA patients. A cross-sectional study was conducted in two tertiary-care hospitals. A total of 137 axSpA patients and healthy volunteers were enrolled. Demographics, disease characteristics, and risk factors for osteoporosis were recorded. TBS, BMD at the lumbar spine, hip, and vertebral fractures were assessed by DXA. Low TBS was defined as a TBS value < 1.230. Factors associated with low TBS were examined by logistic regression. Most patients were male (75.9%) and tested positive for HLA-B27 (88.3%). The mean (SD) age was 42.8 (12.0) years. The mean (SD) of TBS in the axSpA patients was lower than those in the healthy volunteers [1.402 (0.107) vs 1.440 (0.086), respectively; p = 0.002]. The mean (SD) of lumbar BMD in the axSpA patients was higher than in healthy volunteers [1.186 (0.212) vs 1.087 (0.124), p < 0.001], whereas the mean (SD) of femoral neck BMD in the axSpA group was lower than that in the healthy volunteers [0.867 (0.136) vs 0.904 (0.155), p = 0.038]. Disease severity as indicated by sacroiliac joint fusion and a high ASDAS score were associated with low TBS with the odds ratios (95% confidence interval) of 11.8 (1.2-115.4) and 5.2 (1.6-16.9), respectively. In conclusion, axSpA patients had a higher prevalence of low TBS than healthy volunteers. Sacroiliac joint fusion and a high ASDAS score were associated with low TBS.

Relationship between trabecular bone score, bone mineral density and vertebral fractures in patients with axial spondyloarthritis

BACKGROUND

In patients with axial spondyloarthritis, vertebral fracture risk is elevated and not always correlated with bone mineral density (BMD). Trabecular bone score (TBS) may offer some advantages in the assessment of vertebral fracture risk in these patients. The primary objective of this study was to compare TBS and BMD between axial spondyloarthritis patients depending on their vertebral fracture status. Secondary objectives were to estimate the prevalence of morphometric vertebral fractures, and to explore factors associated with fracture, as well as the interference of syndesmophytes on BMD and TBS.

METHODS

A cross-sectional study was conducted. Data were collected on demographic and clinical characteristics, lab results, imaging findings and treatment. Statistical analysis was performed using SPSS v.13 statistical software.

RESULTS

Eighty-four patients (60 men and 24 women; mean age of 59 years) were included. Nearly half (47.6%) of them had lumbar syndesmophytes. The rate of morphometric fracture was 11.9%. TBS showed a higher area under the curve (0.89) than total hip, femoral neck and lumbar BMD (0.80, 0.78, and 0.70 respectively) for classifying patients regarding their fracture status. Nonetheless, the differences did not reach statistical significance. Syndesmophytes affected lumbar spine BMD (p < 0.001), but not hip BMD or TBS. Fractures were associated with TBS, total hip BMD, erythrocyte sedimentation rate and C-reactive protein levels.

CONCLUSIONS

We identified decreased TBS and total hip BMD, as well as increased erythrocyte sedimentation rate and C-reactive protein levels as factors associated with morphometric vertebral fractures. Unlike lumbar spine BMD, TBS is not affected by the presence of syndesmophytes.

Trabecular bone score in rheumatic disease

Patients with rheumatic diseases (RD) are at high risk of osteoporosis (OP) and osteoporotic fractures. The Trabecular bone score (TBS) is a relatively novel method of assessing bone quality, which independently predicts fracture risk regardless of bone mineral density (BMD). A lower TBS in patients with RD compared to controls is shown in most studies concerning TBS and RD. The data obtained indicate that TBS predicts fractures better in RD, especially in patients receiving glucocorticoids, than BMD or the FRAX algorithm. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis in a few studies. However, there is little data in the literature on the effect of rheumatic disease therapy and OP treatment in patients with RD on predictive ability of TBS for incident fracture.

Trabecular Bone Score in Rheumatic Disease

PURPOSE OF REVIEW

Patients with rheumatic disease are at high risk of low bone mass and osteoporotic fracture. Trabecular bone score (TBS), derived from lumbar spine dual-energy x-ray absorptiometry (DXA), is a novel measure of bone texture that independently predicts fracture risk. This review examines the role of TBS in rheumatic disease including fracture prediction.

RECENT FINDINGS

Most studies concerning TBS and rheumatic disease are cross-sectional, with consistent evidence of lower TBS in patients with rheumatic disease compared to controls. Recent studies have shown association and predictive ability of TBS for prevalent fracture, and the few longitudinal studies showed predictive ability of TBS for incident fracture. TBS in ankylosing spondylitis is of interest given the high rates of vertebral fracture and technical difficulty with lumbar spine bone mineral density. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis. Glucocorticoid exposure is associated with lower TBS, and predicts prevalent fracture, in patients with rheumatic conditions.

Prevalence and Associated Factors of Low Bone Mineral Density in the Femoral Neck and Total Hip in Axial Spondyloarthritis: Data from the CASTRO Cohort

Studies on osteoporosis in axial spondyloarthritis (axSpA) have focused on the lumbar segment, and few studies have assessed bone mineral density (BMD) in the hip and femoral neck in these patients. The aim of this study was to evaluate the prevalence of low BMD and osteopenia in the total hip or femoral neck and the factors associated with these conditions in axSpA patients. This was a single-centre, observational, cross-sectional study among consecutive patients with axSpA according to the ASAS criteria from the CASTRO registry. All patients underwent total hip and femoral neck DXA BMD measurements. Low BMD was defined as a Z-score less than −1, and osteopenia was defined as a T-score less than −1. Multivariate logistic and generalised linear regressions were used to evaluate factors independently associated with low BMD and osteopenia in the hip or femoral neck and those associated with variability in BMD, respectively. A total of 117 patients were included, among which 30.8% were female and the mean age was 45 years. A total of 36.0% of patients had low BMD (28.1% in the total hip and 27.4% in the femoral neck), and 56.0% of patients had osteopenia (44.7% in the total hip and 53.8% in the femoral neck). A multivariate logistic regression showed that age, radiographic sacroiliitis and ASAS-HI were independently associated with low BMD in the total hip or femoral neck. Factors that were independently associated with osteopenia were Body Mass Index, disease duration, radiographic sacroiliitis and ASAS-HI. In conclusion, 36% of the patients with axSpA had low BMD in the total hip or femoral neck. A younger age and radiographic sacroiliitis were the most important factors associated with decreased BMD.

Application of the Trabecular Bone Score in Clinical Practice

The trabecular bone score (TBS) was introduced as an indirect index of trabecular microarchitecture, complementary to bone mineral density (BMD), and is derived using the same dual energy X-ray absorptiometry images. Recently, it has been approved for clinical use in Korea. Therefore, we conducted a comprehensive review to optimize the use of TBS in clinical practice. The TBS is an independent predictor of osteoporotic fractures in postmenopausal women and men aged >50 years. The TBS is potentially useful in monitoring the skeletal effects of anabolic agents but not of antiresorptive agents. In postmenopausal women with type 2 diabetes mellitus, the TBS assesses osteoporotic fracture risk not captured by BMD. However, high body mass index and soft tissue thickness can cause underestimation of the TBS; however, this limitation has been improved in recent versions of the TBS software. However, a high precision error and low reproducibility limit the use of TBS. This review may provide information on the application of the TBS in clinical practice based on reliable evidence.

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

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial joints. Altered bone metabolism associated with chronic inflammation leads to both new bone formation in the spine and increased bone loss. It is known that patients with axSpA have a high prevalence of osteoporosis and fractures. However, there is no consensus on which imaging modality is the most appropriate for diagnosing osteoporosis in axSpA. Bone mineral density measurement using dual-energy X-ray absorptiometry is the primary diagnostic method for osteoporosis, but it has notable limitations in patients with axSpA. This method may lead to the overestimation of bone density in patients with axSpA because they often exhibit abnormal calcification of spinal ligaments or syndesmophytes. Therefore, the method may not provide adequate information about bone microarchitecture. These limitations result in the underdiagnosis of osteoporosis. Recently, new imaging techniques, such as high-resolution peripheral quantitative computed tomography, and trabecular bone score have been introduced for the evaluation of osteoporosis risk in patients with axSpA. In this review, we summarize the current knowledge regarding imaging techniques for diagnosing osteoporosis in patients with axSpA.

Performance of bone mineral density and trabecular bone score in assessment of bone quality in Egyptian male patients with ankylosing spondylitis

Background

Osteoporosis is a common complication of ankylosing spondylitis (AS) even in the early stages of disease; however, previously published studies have demonstrated large discrepancies in the reported incidence of osteoporosis, based on measurement of bone mineral density (BMD). The aim of the present study was to compare bone quality using trabecular bone score (TBS) between AS patients and healthy controls and to evaluate factors associated with TBS in patients with AS.

Results

Ankylosing spondylitis patients had significantly lower BMD and T score at the neck of femur and lower total hip BMD than controls (BMD p = 0.010 and 0.032 respectively), (T score p = 0.006 and p = 0.025 respectively). The mean TBS was significantly lower in AS patients than in controls (p < 0.001). Lumbar spine TBS was directly correlated with BMI (p = 0.029) and BMD at the neck of femur (p = 0.016) and BMD of total hip (p = 0.007) while inversely correlated with the Bath AS Metrology Index (BASMI) (p = 0.026), the modified Stoke AS Spinal Score (mSASS) (p = 0.029), ESR (p = 0.031), and CRP (p = 0.033).

Conclusion

TBS evaluation detected lower bone quality in the lumbar spine in patients with AS when compared with matched controls, while lumbar BMD failed to identify it. These findings encourage the use of TBS as a beneficial tool to recognize the risk of axial osteoporosis as early as possible in AS patients. Also, we recommend its use for regular follow up of drug treatment for those patients.

Loss and gain of bone in spondyloarthritis: what drives these opposing clinical features?

The breadth of bone lesion types seen in spondyloarthritis is unprecedented in medicine and includes increased bone turnover, bone loss and fragility, osteitis, osteolysis and erosion, osteosclerosis, osteoproliferation of soft tissues adjacent to bone and spinal skeletal structure weakness. Remarkably, these effects can be present simultaneously in the same patient. The search for a potential unifying cause of effects on the skeleton necessarily focuses on inflammation arising from the dysregulation of immune response to microorganisms, particularly dysregulation of T_H17 lymphocytes, and the dysbiosis of established gut and other microbiota. The compelling notion that a common antecedent pathological mechanism affects existing bone and tissues with bone-forming potential (entheses), simultaneously with variable effect in the former but bone-forming in the latter, drives basic research forward and focuses our awareness on the effects on these bone mechanisms of the increasing portfolio of targeted immunotherapies used in the clinic.

Trabecular Bone Score (TBS) Predicts Fracture in Ankylosing Spondylitis: The Manitoba BMD Registry

INTRODUCTION

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the spine characterized among other features by spinal boney proliferation, back pain, loss of flexibility, and increased fracture risk. Overlying bone limits the utility of bone mineral density (BMD) by dual X-ray absorptiometry (DXA) in the spine. Trabecular bone score (TBS) is a bone texture measurement derived from the spine DXA image that indicates bone quality and fracture risk independent of BMD.

METHODOLOGY

Using the Manitoba Bone Density Program database, patients with diagnosis codes for ankylosing spondylitis, baseline DXA and lumbar spine TBS were identified. Incident nontraumatic fractures (major osteoporotic [MOF], clinical spine, hip, and all fracture) were identified from population based databases. Cox-proportional hazard models are presented.

RESULTS

We identified 188 patients with diagnosed AS. TBS was lower in those with incident MOF (1.278 ± 0.126, compared to 1.178 ± 0.136, p < 0.001). Unadjusted TBS and FRAX-MOF-BMD adjusted predicted major osteoporotic fracture (N = 19) (hazard ratio [HR] 2.04, 95% confidence interval [CI]: 1.28-2.26, p = 0.003; HR 1.81, 95% CI: 1.11-2.96, p = 0.018). TBS unadjusted and FRAX-MOF-BMD adjusted also predicted clinical spine fracture (N = 7) (HR 2.50, 95% CI: 1.17-5.37; p = 0.019; HR 2.40 95% CI: 1.1-5.25; p = 0.028). Higher HRs were observed for prediction of hip fracture (N = 6), but these did not achieve statistical significance (FRAX-adjusted HR 1.74, 95% 0.73-4.17; p = 0.211). Unadjusted models show TBS was predictive of all fracture (N = 27) (HR 1.60, 95% CI: 1.08-2.39; p = 0.020), which was borderline significant after adjustment for FRAX-MOF-BMD (HR 1.51, 95% CI: 1.00-2.29; p = 0.052).

CONCLUSION

We report the first analysis of TBS for fracture prediction as an incident event in AS. TBS independently predicted major osteoporotic and clinical spine fracture in AS independent of FRAX.

Trabecular bone loss contributes to radiographic spinal progression in patients with axial spondyloarthritis

OBJECTIVES

To investigate the longitudinal relationship between trabecular bone loss and spinal progression in axial spondyloarthritis (axSpA).

METHODS

Patients enrolled in the Incheon Saint Mary's axSpA prospective observational cohort were evaluated. The number of syndesmophytes was assessed by two trained readers at baseline and at 2 and 4 years follow-up. Trabecular bone loss was assessed using the trabecular bone score (TBS). Disease activity measures included the BASDAI, ASDAS, CRP, and ESR. The relationship between trabecular bone loss and radiographic damage was investigated using generalized estimating equation models with 2 year time lags.

RESULTS

Of the 245 patients included (80% males; mean (SD) age, 37 (12) years), 26 (11%) had mild trabecular bone loss (1.23-1.31) and 25 (10%) had severe trabecular bone loss (≤1.23) at baseline. Trabecular bone loss was associated with longitudinal radiographic spinal progression. Those with severe trabecular bone loss at baseline had an average 0.42 more syndesmophytes/2 years than those with normal TBS. Multivariate analysis revealed that severe trabecular bone loss compared with normal TBS resulted in an additional 0.4 syndesmophytes over 2 years. Adjusting for significant clinical factors revealed that both mild and severe trabecular bone loss were independent risk factors for new syndesmophyte formation over the next 2 years (OR [95% CI] = 2.4 [1.1-5.1]) and OR [95% CI] = 4.0 [1.6-9.7], respectively).

CONCLUSIONS

Trabecular bone loss is longitudinally associated with spinal progression of axSpA. The more severe the trabecular bone loss, the stronger the effect on the progression of the spine.

Trabecular bone score value is associated with new bone formation independently of fat metaplasia on spinal magnetic resonance imaging in patients with ankylosing spondylitis

OBJECTIVE

To evaluate the association between trabecular bone score (TBS) and new bone formation in ankylosing spondylitis (AS) patients, and to investigate whether TBS is independently associated with new bone formation.

METHOD

Sixty-eight patients with AS underwent spinal magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry of the lumbar spine to measure TBS and bone mineral density at baseline. Lateral radiographs of the cervical and lumbar spine (baseline and 2 years) were assessed for new bone formation (syndesmophyte formation and/or growth combined), and spinal MRIs were assessed for the presence or absence of fat metaplasia (FM) at the first to fourth lumbar vertebrae. The factors associated with new bone formation were analysed at the patient level and the vertebral level.

RESULTS

New bone formation had developed in 17 patients (25%) at 2 year follow-up. Patients with new bone formation had a higher prevalence of FM and lower TBS at baseline than patients without new bone formation (p = 0.013 and p = 0.041). At the patient level, FM on MRI and low TBS (< 1.23) were significantly associated with new bone formation. At the vertebral level, new bone formation had developed in 25 out of 231 vertebrae (11%) after 2 years. Vertebrae with both FM on MRI and low TBS tended to have more new bone formation (p < 0.001). Syndesmophytes and low TBS (< 1.23) independently increased the risk of new bone formation at the level of individual vertebrae.

CONCLUSION

At both patient and individual vertebral levels, low TBS was associated with new bone formation independently of FM on MRI.

[Evaluation of the trabecular bone score (TBS) in routine clinical care of patients with inflammatory rheumatic and non-inflammatory diseases : Correlation with conventional bone mineral density measurement and prevalence of vertebral fractures]

Hintergrund

Osteoporosebedingte Frakturen sind bei Patienten mit rheumatoider Arthritis (RA) häufig. Die Messung der Knochenmineraldichte (KDM) mit der Dual-Energie-Röntgenabsorptionsmessung (DXA) allein sagt das Frakturrisiko nur begrenzt voraus. Der Trabecular Bone Score (TBS) ist ein Surrogatmarker für die trabekuläre Mikroarchitektur des Knochens, der das Frakturrisiko unabhängig von der KDM vorhersagen kann.

Ziel

Ermittlung der Prävalenz von KDM, TBS und osteoporotisch bedingten Wirbelkörperbrüchen („vertebral fractures“ [VF]) bei Patienten mit RA im Vergleich zu Kontrollen mit nichtentzündlichen Muskel-Skelett-Erkrankungen (MSK).

Methoden

Die Daten von Patienten mit von Rheumatologen diagnostizierter RA und verfügbaren TBS- und DXA-Messungen, die in unserem Krankenhaus von 2006 bis 2014 erhoben wurden, wurden retrospektiv analysiert. Den RA-Patienten wurden Kontrollen mit nichtentzündlichen MSK zugeordnet. Eine „reduzierte Knochengesundheit“ wurde definiert als ein T‑Score <−1,0 und/oder ein TBS-Wert <−1,31. Statistische Vergleiche wurden mit dem Mann-Whitney- und dem Wilcoxon-Test durchgeführt.

Ergebnisse

Es wurden 143 Patienten mit RA (Alter 72,1 ± 11,1 Jahre, 72 % weiblich) und 106 Kontrollen (Alter 69,6 ± 12,6 Jahre, 75 % weiblich) eingeschlossen. RA-Patienten hatten häufiger eine erniedrigte KDM (n = 102; 71,3 %) und einen erniedrigen TBS-Wert (n = 125; 87,4 %) als die Kontrollen (n = 63; 59,4 % und n = 79; 74,5 %, p = 0,049 und p = 0,009). RA-Patienten hatten mehr VF (n = 52, 36,4 %) als Kontrollen (n = 24, 22,6 %, p = 0,02). Insgesamt hatten 20 Patienten mit VF (26,3 %) eine normale Wirbelsäulen-KDM und 9 (11,8 %) auch eine normale Hüft-KDM. Bei Patienten mit VF war die Kombination eines niedrigen TBS bei normaler WS-KDM häufiger als ein normaler TBS bei niedriger WS-KDM (p = 0,008 für RA, p = 0,025 für Kontrollen).

Diskussion

VF treten bei Patienten mit normaler KDM auf. Bei Patienten mit VF wurde eine niedrige TBS bei normaler Wirbelsäulen-KDM häufiger gefunden als eine normale TBS bei niedriger Wirbelsäulen-KDM. Die Messung des TBS scheint für die Erkennung eines erhöhten Frakturrisikos bei RA-Patienten mit normaler WS-KDM nützlich zu sein.

Longitudinal Association Between Trabecular Bone Loss and Disease Activity in Axial Spondyloarthritis: A 4-year Prospective Study

OBJECTIVE

To investigate whether trabecular bone loss is longitudinally associated with disease activity measures in patientswith axial spondyloarthritis (axSpA).

METHODS

Data from patients enrolled in the Incheon Saint Mary's axSpA prospective observational cohort were evaluated. Trabecular bone loss was assessed using the trabecular bone score (TBS). The relationship between TBS and disease activity measures [Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP)] was investigated using generalized estimating equation (GEE) models.

RESULTS

Four-year followup data from 240 patients (80% males, mean age 37 ± 12 yrs) were evaluated. At baseline, higher disease activity according to ASDAS-ESR and ASDAS-CRP showed a trend toward lower TBS (p = 0.003 and p = 0.016, respectively). Univariate GEE analyses showed a significant association between TBS and disease activity measures over time, with the exception of BASDAI. Univariate analysis showed a longitudinal association between TBS and age, smoking, and spinal structural damage. In multivariate GEE analysis, ASDAS-ESR, ASDAS-CRP, ESR, and CRP were longitudinally associated with TBS after adjustment for confounding factors. ASDAS scores and inflammatory markers were longitudinally associated with TBS in patients with ankylosing spondylitis (AS; 79%), but not in patients with nonradiographic axSpA (nr-axSpA). BASDAI scores showed no relationship with TBS in either the AS or nr-axSpA groups.

CONCLUSION

Trabecular bone loss in patients with axSpA, assessed using the TBS, showed a longitudinal association with ASDAS scores and inflammatory markers.

Low bone mineral density predicts the formation of new syndesmophytes in patients with axial spondyloarthritis

Background

This study aimed to investigate whether the presence of low bone mineral density (BMD) in patients with axial spondyloarthritis (axSpA) predicts formation of new syndesmophytes over 2 years.

Methods

One hundred and nineteen patients fulfilling the imaging arm of the Assessment of SpondyloArthritis International Society axSpA criteria were enrolled. All patients were under 50 years of age. The modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) was assessed by two trained readers blinded to the patients’ data. BMD (lumbar spine, femoral neck or total hip) at baseline was assessed using dual-energy absorptiometry. Low BMD was defined as Z score ≤ − 2.0. Spinal radiographic progression was defined as worsening of the mSASSS by ≥ 2 points over 2 years. Logistic regression analyses were performed to identify predictors associated with development of new syndesmophytes and spinal radiographic progression.

Results

At baseline, 19 (16%) patients had low BMD. New syndesmophytes had developed in 22 (21%) patients at 2-year follow-up. New syndesmophyte formation after 2 years occurred more in patients with low BMD than in those with normal BMD (p = 0.047). In the multivariable analysis, current smoking, existing syndesmophytes and low BMD at baseline were associated with spinal radiographic progression (OR (95% CI) 3.0 (1.1, 7.7), 4.6 (1.8, 11.8) and 3.6 (1.2, 11.2), respectively). The presence of syndesmophytes at baseline and low BMD were predictors of new syndesmophytes over the following 2 years (OR (95% CI) 5.5 (2.0, 15.2) and 3.6 (1.1, 11.8), respectively).

Conclusions

Low BMD and existing syndesmophytes at baseline were independently associated with the development of new syndesmophytes in young axSpA patients.