Background Systemic sclerosis (SSc) is a rare connective tissue disease characterized by vascular, immune and fibrotic changes in the skin and internal organs. Rheumatoid arthritis (RA) is a chronic inflammatory disease and has well known detrimental effect on bone mass. However number of studies assessing the effect of SSc on bone mass is scanty.
Objectives To compare the bone mineral density (BMD) in patients with systemic sclerosis and rheumatoid arthritis.
Methods Patients with SSc and RA were consecutively recruited. Patients who had disorders that effect bone metabolism were excluded. Demographic characteristics of the patients and their risk factors for osteoporosis were recorded. Body mass index (BMI), menopausal status, disease duration, exercise activity and laboratory parameters of bone metabolism were assessed in all patients. Bone mineral density of the lumbar spine and the total hip were measured by DXA using a densimeter.
Results Forty-three female patients with SSc, and 38 age matched female patients with RA were included in the study. Mean age of the patients with SSc was 50.3±11.4 and RA was 50.4±9.5 years. Twenty-two (51.1%) patients in SSc group and 21(55.2%) in RA group were postmenopausal. Mean BMI of SSc and RA was 26.1±6.1 and 30.1±5.3, respectively (p<0.05). Mean duration of menopause of SSc and RA group were 10.9±7.1 and 10.2±7.1 years respectively. Diagnostic delay was longer in SSc versus RA group (5.5±5.3 and 3.2±4.1 years respectively`; p<0.05). There was no significant difference in the mean disease durations in SSc and RA group (10.0±8.2 and 10.4±7.1 years, respectively). SSc group had 36 (83.7%) non-smokers, 5 (11.6%) ex-smoker, 2 (4.6%) smokers, and RA had 27 (71.1%) non-smokers, 6 (15.8) ex-smokers, and 5 (13.1%) smokers. Alcohol consumption of patients was smilar between groups (2 in SSc and 1 in RA). None of the patients in SSc and RA groups had regular exercise habit. In RA group 24 (63.2%) patients used low doses corticosteroids where as none in SSc. Mean level of CRP was above the normal upper limit in both group and higher in RA group (p<0.05). Mean 25-hydroxy vitamin D level was lower in SSC (23.1±7.9) than RA (34.5±19.6) (p<0.05). Mean BMD value and T score at lumbar spine were similar between groups. BMD of the total hip (SSc-0,796±0,15 vs RA-0.872±0.127 p=0.02), mean T score of femoral neck (SSc; -1.2±1.2 vs RA; -0.4±1.0 p=0.006) and total hip (SSc;-1.2±1.2 vs RA;-0.6±1.0 p=0.01) were significantly lower in patient with SSc than RA. As expected there were negative correlation between duration of menopause and BMD (lumbar spine r:-0.35, p=0.01; total hip r:-0.38, p=0.008 ), T score (lumbar spine r:-0,34, p=0.02; total hip:-0,40, p=0.006). Disease duration negatively correlated with T score of total hip (r:-0.44, p<0.0001). There was positive correlation between level of vitamin D and BMD of lumbar spine (r:0.29, p<0.05), T score of lumbar spine (r:0.292, p<0.05). The modified Rodnan skin score negatively correlated with BMD of femur neck (r:-0.40, p:0.01) and total hip (r:-0.41, p:0.01), T score of femur neck(r:-0.39, p:0.01) and total hip (r:-0.41, p:0.009).
Conclusions Patient with SSc had lower BMD at the hip in comparison to RA. Also, patients with SSc had lower mean vitamin D level. Bone mass in patients with SSc seems to be associated with the modified Rodnan skin score, level of vitamin D, prolonged duration of disease and menopause.
Disclosure of Interest None Declared