Prevalence of Low Bone Density and Fracture Risk Assessed with the FRAX Tool in German Patients with Axial Spondyloarthritis: A Cross-Sectional Study

TL;DR

This study finds that German patients with axial spondyloarthritis have a high risk of low bone density and fractures, emphasizing the importance of using the FRAX tool for fracture risk assessment.

Contribution

The study provides new data on FRAX-based fracture risk assessment in German patients with axial spondyloarthritis.

Findings

44.8% of patients had low bone density at the lumbar spine and 60.4% at the femoral neck.

Female patients had higher FRAX scores for major osteoporotic fractures compared to males.

Patients with previous fractures had significantly higher FRAX scores for major osteoporotic fractures.

Abstract

Introduction: Chronic inflammation in axial spondyloarthritis (axSpA) promotes osteoclast formation and bone resorption, leading to osteoporosis and an increased risk of fragility fractures. Osteoporotic fractures significantly impact the quality of life in patients with axSpA. While the Fracture Risk Assessment Tool (FRAX) is widely used to evaluate fracture risk, data on FRAX-based fracture risk assessment in axSpA, particularly in German patients, are limited. Objective: The primary objective of this study was to assess the prevalence of low bone mineral density (BMD) and fracture risk using FRAX for major osteoporotic fractures (MOF) and hip fractures (HF) in German patients with axSpA. Secondary objectives were to compare FRAX scores and BMD between genders and between patients with and without previous fractures, and to identify which FRAX parameters were most frequently abnormal. Materials and Methods: This retrospective study analyzed demographic and clinical data, along with DXA-measured BMD, T-scores and Z-scores of the lumbar spine and femoral neck in 58 axSpA patients aged 43–81 years from routine clinical practice. Calculations for MOF and HF were performed using the FRAX model for Germany. Low BMD was defined as a T-score < −1 SD or a Z-score < −2 SD. Statistical analyses included independent t-tests and chi-square tests. Results: The mean age of patients was 65 years with a mean BMI of 29.5 kg/m2. The prevalence of low BMD was 44.8% at the lumbar spine and 60.4% at the femoral neck. Overall, 10 (17.2%) patients reported previous fractures of the spine, forearm, hip, or shoulder. Female patients had higher FRAX scores for MOF (8.2%) than males (6.8%, p = 0.02), while male patients had higher FRAX scores for HF (2.8% vs. 2%, p = 0.04). There was no significant difference in BMD between patients with or without a history of fracture. However, patients with previous fractures had significantly higher FRAX scores for MOF (10.2%) compared to those without fractures (7.3%, p = 0.030); the difference in HF scores was not statistically significant (3.5% vs. 2%, p = 0.056). Conclusions: This study highlights the elevated fracture risk in axSpA patients assessed with FRAX. In this cohort, BMD alone was not associated with fracture history, suggesting that other factors—such as age, sex, glucocorticoid exposure, and prior fractures—may play a more prominent role. FRAX provides a valuable tool for evaluating fracture risk in axSpA, emphasizing the importance of a comprehensive assessment that incorporates both clinical risk factors and BMD.

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