Systemic sclerosis (SSc) is a connective tissue disease characterized by initial microvascular damage, immune system activation and progressive fibrosis with insufficiency of internal organs. Gastrointestinal (GI) involvement is characterized by atrophy of the smooth muscle and small bowel hypomotility, mainly resulting from an autonomic nerve dysfunction. These modifications significantly affect gut transit and nutrient absorption, thus leading to malnutrition deficit induced by malabsorption. Nutritional deficit induced by malabsorption might also lead to bone alterations. This study aims to evaluate the relationship between malnutrition and bone status. Thirty-six postmenopausal female patients fulfilling the ACR 2013 criteria for SSc underwent dual-energy X-ray absorptiometry scan (DXA) to detect quantitative lumbar spine bone mineral density (BMD) and trabecular bone score (TBS) analysis to detect bone quality. Data from DXA also allow to assess body composition and provide several quantitative parameters, including free fat mass index (FFMI) that identifies the patient with malnutrition (values <15 kg/m2 in women and 17 kg/m2 in men), according to the ESPEN criteria. Body mass index (BMI) was calculated for all SSc patients and every patient completed a diary reporting GI symptoms. Two groups of SSc patients with or without diagnosed malnutrition according to FFMI parameter were identified. Malnourished SSc patients showed significantly lower weight (p = 0.01) and BMI (p = 0.001), as well as lower serum levels of hemoglobin (p = 0.009), albumin (p = 0.002), PTH (p = 0.02) and 25OH-vitamin D (p = 0.008). DXA analysis showed significantly lower lumbar L1-L4 T-score (p = 0.009) and BMD values (p = 0.029) in malnourished SSc patients. Consistently, TBS values were significantly lower in malnourished patients (p = 0.008) and correlated with BMD (at any site) and serum albumin levels (p = 0.02). In addition, FFMI positively correlated with bone parameters as well as with symptoms of intestinal impairment in malnourished SSc patients. Finally, GI symptoms significantly correlated with BMD but not with TBS. This pilot study shows that in malnourished SSc patients (2015 ESPEN criteria: FFMI<15 kg/m2), an altered bone status significantly correlates with GI involvement, in terms of symptoms being mainly due to intestinal involvement together with the presence of selected serum biomarkers of malnutrition.
Keywords: bone parameters; malnutrition; systemic sclerosis.