Background/Purpose: To study the prevalence and risk factors of low bone mineral density (BMD) in patients with systemic sclerosis (SSc).

Methods: Consecutive patients who fulfilled the ACR criteria for SSc were screened for BMD and BC (fat and lean mass) by DXA scan.  An equal number of age and gender matched healthy controls were also recruited for the same measurements.  Data on risk factors for osteoporosis were also compared between patients and controls.  In SSc patients, the extent of skin involvement was assessed by the modified Rodnan skin score (mRSS) and organ damage was evaluated by the Medsger SSc severity index.  Risk factors for low BMD in SSc patients were studied by linear regression analyses.

Results: 84 patients with SSc were studied (89% women; age 49.4±11.3 years; disease duration 7.8±6.4 years).  Eighteen (21%) patients had diffuse cutaneous SSc while the other 66 (79%) patients had limited cutaneous SSc according to the LeRoy classification. Nineteen(23%) SSc patients had been treated with glucocorticoids.  The mean±SD and median (IQR) mRSS score of the SSc patients was 11.2±9.8 (range 0-40) and 8 (IQR 4-14), respectively.  The highest mean Medsger severity score was observed for involvement of skin (1.33±0.83), followed by joint/tendon (0.89±1.44), peripheral vascular system (0.86±1.00), lung (0.68±1.04), heart (0.23±0.68) and the kidney (0.14±0.60).  Four (5%) SSc patients required aids for walking and 4(5%) other patients were chair-bound.  Except for significantly lower body mass index (BMI) and body weight in SSc patients, the frequency of osteoporosis risk factors was similar to that of controls.  The BMD of the lumbar spine, total hip, femoral neck and whole body was significantly lower in SSc patients than controls after adjustment for age, sex, BMI and menopausal status.  Fourteen(17%) patients with SSc had low BMD of the lumbar spine expected for their age (Z score <-2.0) and 5 (6%) patients had a total hip Z score of <-2.0.  Osteopenia of the lumbar spine, total hip and femoral neck, defined as a Z score of between -1.0 and -2.0, occurred in 37%, 45% and 40% of the SSc patients, respectively.  Four (7%) patients reported a personal history of fracture (all non-vertebral; two arose from low impact injury).  The proportion of patients with osteopenia of the hip, femoral neck and lumbar spine was significantly higher in SSc patients than controls.  Linear regression analyses revealed that increasing age was an independent risk factor for lower BMD in all sites.  Low BMI was independently associated with low BMD of the total hip and femoral neck, whereas menopause was an independent associated factor of low BMD at the lumbar spine.  Other covariates such as the subtype of SSc (diffuse vs limited SSc), parity, smoking, drinking, female sex, disease duration, menopause, ever use of glucocorticoids and family history of fractures were not significantly associated with lower BMD at these sites.  The skin score and disease severity scores in any organs were not significantly associated with the BMD values.

Conclusion: BMD of the spine and hip is significantly lower in SSc patients than healthy subjects, which is independent of age, sex, menopause, low BMI and altered body composition.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-and-risk-factors-of-low-bone-mineral-density-in-chinese-patients-with-systemic-sclerosis-a-case-control-study/