Background Vertebral fractures (VF) are the hallmark of bone fragility. Patients with systemic lupus erythematosus (SLE) are at high risk of developing prevalent VF. Although several risk factors for VF in patients with SLE have been suggested, there is limited longitudinal supporting data in the literature.
Objectives The aims of this study are to determine the incidence of VF and to evaluate possible associations between potential risk factors and the occurrence of VF in women with SLE.
Methods Consecutive patients with SLE were enrolled in a prospective, observational study from 2006 to 2015. Information on potential risk factors, including demographics, clinical data and bone mineral density (BMD) at the lumbar spine and hip on dual-energy X-ray absorptiometry was collected at baseline and follow-up. Semi-quantitative analysis was used to determine incident VF on lateral thoracic and lumbar radiographs, defined as any vertebral body graded normal at baseline and at least mildly deformed (20–25% reduction or more in any vertebral height) during follow-up. Differences in baseline characteristics were assessed in patients with and without radiographic VF.
Statistical analysis: The Chi-square or Fisher's exact test, independent samples t-test, and Mann-Whitney U-test were used as appropriate to compare baseline characteristics of patients with and without prevalent or incident VF. Possible risk factors for incident VF were assessed by multivariate logistic regression analysis.
Results Of 110 SLE patients included, with a median follow-up of 8 (IQR 8–9) years, 22 (20%) had radiographic VF at baseline; 35 (32%) patients had a new VF. The annual incidence rate of new morphometric VF was 3.5 (95% CI 2.4–4.91) per 100 patient/years. Most fractures were located in the mid-thoracic and thoracolumbar region of the spine. Table 1 shows sociodemographic and clinical differences between patients with and without VF. In the multivariable analysis, VF were significantly associated with baseline BMD at the total hip and longer disease duration. Cumulative glucocorticoid dose, postmenopausal status and previous prevalent VF were not associated with VF.
Conclusions In this SLE cohort in daily clinical practice, radiographic VF were frequently present in SLE patients, especially those with longer disease duration and low hip BMD.
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Acknowledgements This work was supported in part by grant from FIS/IMSS/PROT/MD15/1500.
Disclosure of Interest None declared