Bone mineral density and trabecular bone score assessment in systemic sclerosis: A cross-sectional study

Osteoporosis is associated with anti-topoisomerase I positivity and glucocorticoids use in patients with systemic sclerosis

OBJECTIVES

Patients with systemic sclerosis (SSc) are at increased risk for osteoporosis (OP) and associated fragility fractures. This study aimed to identify underlying risk factors for these conditions in patients with SSc.

METHODS

This cross-sectional study was based on a large prospective cohort of patients with SSc using retrospectively collected bone health data. OP was defined as the presence of a T-score below -2.5 at the femoral neck or lumbar spine, a previous major osteoporotic fracture, or the prescription of anti-osteoporotic therapy.

RESULTS

A total of 485 patients fulfilling the ACR/EULAR 2013 diagnostic criteria for SSc, followed in the Lille University Hospital, were included in the study. The prevalence of OP was 23%; fragility fractures occurred in 18% of patients. OP was associated with higher age, diffuse cutaneous subset, interstitial lung disease (ILD), anti-topoisomerase I positivity, treatment with glucocorticoids (GC) and DMARDs in univariable analysis. Multivariable analysis indicated that higher age (OR 1.06 [95%CI 1.04-1.08]), anti-topoisomerase I antibody positivity (OR 2.22 [1.18-4.16]) and treatment with GC (OR 4.48 [2.42-8.26]) were significantly and independently associated with OP.

CONCLUSION

Our study shows that OP risk in patients with SSc is determined by age, disease-related factors such as diffuse cutaneous subset, ILD and anti-topoisomerase I antibody positivity, but also treatment with GC independently of other factors.

"The least significant change on bone mineral density scan increased in patients with higher degrees of obesity"

BACKGROUND

The least significant change (LSC) threshold of 0.03 g/cm² is used to interpret bone mineral density (BMD) scans in the general population. Our working hypothesis was that the current LSC threshold would not be applicable in obese populations.

AIMS

The aim of this study was to calculate the LSC in an obese population.

METHODS

We performed an interventional study among 120 obesity patients, in whom two measurements of BMD were performed at 3 sites. Pairs of measures were used to calculate the LSC, using the Bland and Altman method.

RESULTS

We calculated that the LSC was 0.046 g/cm² at the lumbar spine, 0.069 g/cm² at the femoral neck, and 0.06 g/cm² at the total hip. We also calculated the LSC for each class of obesity and observed an increase in LSC with increasing body mass index (BMI). We calculated a LSC of 0.05 g/cm² in patients with class 2 or class 3 obesity, whereas the LSC in patients with class 1 obesity is similar to the threshold used in the general population.

DISCUSSION

In obese population, like BMD, LSC is higher than the threshold value of the general population, and increases with increasing BMI.

CONCLUSION

LSC of 0.05 g/cm² could be used in clinical practice in patients with class 2 or 3 obesity. These findings should help to improve the interpretation of BMD scans in these patients and optimize their management.

TRIAL REGISTRATION NUMBER

Comité de Protection des Personnes Ile-de France VII, France.

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.