AB0608 BONE MINERAL DENSITY, VITAMIN D STATUS AND BONE METABOLISM IN A COHORT OF ADULT PATIENTS WITH INFLAMMATORY BOWEL DISEASE

Background:Patients with inflammatory bowel disease (IBD) have an increased risk of low bone mineral density (BMD) and bone fractures due to several mechanisms. However, the best management of osteoporosis in this population is yet to determine.Objectives:To evaluate bone mineral density and other clinical, analytical and demographic features related with the risk of bone fractures in an IBD cohort.Methods:Retrospective monocentric study including all the patients with IBD consecutively reffered from Gastroenterology to the Rheumatology Department in a tertiary university hospital between January of 2013 and October 2020. Demographic, clinical and analytical data and BMD by dual-energy X-ray absorptiometry (DXA) (total hip, femoral neck and lumbar spine) were collected at the time of the first visit in the Rheumatology outpatient center. Correlations between variables were evaluated by Spearman rank test and Mann-Whitney U test was used in the comparison analysis between groups (significance level at p<0.05), using SPSS 25.0 software.Results:A total of 222 patients were included: 128 (57.7%) females, mean age of 43.4 (±13.6) years, mean IBD duration of 11.6 (±9.7) years. Regarding IBD: 163 (73.4%) had Crohn’s disease (CD) and 59 (26.6%) had ulcerative colitis (UC); azathioprine (41.9%) and infliximab (29.8%) were the most frequently used drugs; 10 patients (4.5%) were taking glucocorticoids, 104 (46.8%) had been previously treated with glucocorticoids and 65 (29.3%) had already been exposed to high doses of glucocorticoids (prednisolone equivalent dose ≥ 7.5 mg/day).Ten patients (4.5%) had previous fragility fractures and 32 (14.4%) fulfilled diagnostic criteria of osteoporosis by DXA (T score ≤ -2.5). One hundred eighty-one (81.5%) patients exhibited low levels of 25-hydroxy vitamin D (<30ng/mL), 24 (10.8%) had high levels of parathormone and 150 (67.6%) showed elevated serum concentrations of beta-carboxy-terminal type-1 collagen crosslinks (beta-CTX). Three patients (1.4%) were under treatment with bisphosphonates and 18 (8.1%) were taking calcium and/or vitamin D supplements.Of interest, serum levels of albumin correlated negatively with beta-CTX (r=-0.401; p<0.001) and positively with osteocalcin (r=0.259; p<0.001). Correlations between clinical/analytical variables and BMD are presented in Table 1.Patients under glucocorticoids had lower mean total hip BMD (0.874±0.159 vs 1.008±0.176; p=0.022) and femoral neck BMD values (0.797±0.174 vs 0.933±0.179; p=0.014) in comparison with the group of patients that were not taking glucocorticoids.No statistically significant differences in BMD values were found between the following subgroups: DC vs UC; normal vs low levels of 25-hydroxy vitamin D; patients exposed vs not exposed to high doses of glucocorticoids.Table 1.Correlations between clinical/analytical variables and the BMD in an IBD population (BMD: Bone Mineral Density; IBD: Inflammatory Bowel Disease; n.s. not significant).Total hip BMDFemoral neck BMDLumbar Spine BMDAger=-0.356;p<0.001r=-0.469;p<0.001r=-0.259;p<0.001Age at IBD diagnosisr=-0.254;p<0.001r=-0.327;p<0.001r=-0.226;p=0.001IBD durationr=-0.147;p=0.031r=-0.218;p=0.001n.s.Hemoglobinr=0.249;p<0.001r=0.209;p=0.002n.s.Albuminr=0.189;p=0.005r=0.208;p=0.002n.s.Erythrocyte sedimentation rater=-0.231;p=0.001r=-0.206;p=0.003n.s.Conclusion:Our results show an important prevalence of undiagnosed and untreated osteoporosis in patients with IBD. Stronger correlations were found between clinical/analytical variables and femoral neck BMD. Of note are the weak correlations of BMD with acute-phase markers (negative correlation with erythrocyte sedimentation rate and positive correlations with hemoglobin and albumin) and of nutritional status (evaluated by albumin) with bone markers (negative correlation with the bone reabsorption marker beta-CTX and positive correlation with the bone formation marker osteocalcin).Disclosure of Interests:None declared.