Bone Mineral Density and Fracture Risk Assessment in Patients of Systemic Sclerosis

Abstract

Background: Systemic sclerosis (SSc) is a chronic disease presenting in the age group of 20-50yrs and females are more affected than males. Osteoporosis is common in many rheumatological diseases and an association has been well established in Rheumatoid Arthritis and Systemic Lupus Erythematosus. However, there is no such robust data in patients affected with SSc. Our study aimed to measure Bone Mineral Density and assess the risk of fracture in patients of systemic sclerosis using the Fracture Risk Assessment using (FRAX) algorithm. Methodology: The case control study conducted in a tertiary care hospital included 24 patients of age 18-45years with systemic sclerosis and 24 age and sex matched healthy controls. 62.5% cases were antiScl-70 antibody positive, 62.5% had interstitial lung disease and 37.5% had pulmonary arterial hypertension. The BMD of Scl-70 antibody positive patients was 0.64± 0.08 gm/sq.cm at neck of femur, 0.70± 0.08 gm/sq cm at lumbar spine and 0.37± 0.06 gm/sq. cm at forearm. A significant lower T score at neck of femur was noted in cases as compared to controls (-1.91± 10 vs -0.32± 1.06, p=0.001). The mean FRAX score value for major osteoporotic fracture in cases, was 1.46± 0.61% with maximum value of 3% and minimum value of 0.9%. Whereas, for the hip fracture mean FRAX was 0.83± 0.07% with range of 0.7% to 1.9%. A significant difference was noted in risk of major osteoporotic fractures between cases and controls (p=0.017). On multivariate regression models computed to analyse the covariates of BMD for neck of femur, lumbar spine and forearm, it was observed that serum vitamin D levels, presence of pulmonary hypertension and/or ILD were significant covariates of BMD neck of femur. Conclusion: Systemic sclerosis is associated with significantly low bone mineral density compared to controls. The bone mass was negatively correlated with involvement of internal organs and serum iPTH levels. SSc may be considered as an independent risk factor for osteoporosis and patients of SSc should be evaluated for BMD with DEXA scan to prevent osteoporotic fractures.