Bone density in Moroccan women with systemic scleroderma and its relationships with disease-related parameters and vitamin D status

Abstract

In this case-control study, our first aim was to evaluate the bone mineral density (BMD) in women with systemic sclerosis (SSc) and its correlates. Secondarily, we aimed to evaluate 25-hydroxyvitamin D3 status and its relationships with disease parameters and BMD. Sixty patients with SSc and 60 age-and gender-matched controls were included in the absence of confounding factors that interfere with bone metabolism. Body mass index, menopausal status, familial history of osteoporosis and/or fractures; personal fracture history; exercise activity and laboratory parameters of bone metabolism were assessed in patients and controls. BMD was measured by using a dual-energy X-ray absorptiometry in lumbar spine (L1-L4) and femoral neck. The 25-hydroxyvitamin D3 was measured in a subgroup of 30 patients and in a subgroup of 30 matched controls. Systemic manifestations of SSc, biological inflammatory parameters, functional disability (scleroderma health assessment questionnaire (S-HAQ)) and immunological status of disease were collected in patients' group. The mean age of patients was 49.44 ± 13.07 years versus 49.55 ± 12.11 in controls. The mean disease duration was 9.63 ± 5.9 years. SSc patients had a significantly earlier age and longer duration of menopause than controls (P = 0.003). Phosphocalcic metabolism parameters were within normal ranges in both groups. BMD was significantly lower in SSc patients than in controls both in lumbar spine (-2.97 ± 0.25 in patients vs. 0.46 ± 0.11 in controls) and femoral neck (-1.93 ± 0.32 in patients vs. -0.81 ± 0.69 in controls) (P < 0.01). Thirty-six (60%) patients versus 15 (25%) controls had osteoporosis and 19 (31.7%) patients versus 13 (21.7%) controls had osteopenia (P < 0.01). In correlation analysis and in multiple regression models, there were significant correlations between BMD and longer duration of SSc, severe joint involvement (severe joint pain and erosive arthropathy), malabsorption syndrome and the positivity of anti-DNA topoisomerase I antibodies. Also, we found very low levels of vitamin D (10.88 ± 2.68 ng/ml) comparing to controls (57.41 ± 4.18 ng/ml) (P = 0.001). Vitamin D levels were correlated with the severity of joint pain, with immunological status and with BMD in lumbar spine and femoral neck (P < 0.01). In our sample, we state the importance of decreased BMD in Moroccan women with SSc with a high frequency of osteoporosis comparing to healthy controls. Bone loss seems to be associated with prolonged disease duration, severe joint involvement, malabsorption syndrome and immunological status. Also, SSc patients had lower levels of 25-hydroxyvitamin D3 than controls. Larger studies are needed to confirm those findings.