Supplementary Material for: Risk Factors for Low Bone Density in Inflammatory Bowel Disease: Use of Glucocorticoids, Low Body Mass Index, and Smoking

Background: Inflammatory bowel disease (IBD) patients are reported to have lower bone density compared to healthy controls. There is limited consensus regarding factors affecting bone density among these patients. Our aim, therefore, was to determine clinical and genetic variables that contribute to lower bone mineral density (BMD) in IBD patients. Methods: A cross-sectional study of IBD patients treated in a tertiary referral center was performed. Epidemiological and clinical data were collected, and genetic testing for the common mutations in Nucleotide-binding Oligomerization Domain-containing protein (NOD)2 was performed. We examined correlations between the different variables and BMD in the total hip, femoral neck, and lumbar spine. Results: Eighty-nine patients (49% males, 67 Crohn’s disease [CD]) participated in the study. 42Forty-two (63%) of the CD and 13 (59%) of the ulcerative colitis patients met the criteria for osteoporosis/osteopenia. Factors associated with lower Z scores were low body mass index (BMI; r = –0.307, p = 0.005), use of glucocorticoids (likelihood ratio [LR] 5.1, p = 0.028), and a trend for male gender (LR = 3.4, p = 0.079). Among CD patients, low bone density showed borderline significance for association with gastrointestinal surgery (LR = 4.1, p = 0.07) and smoking (LR = 3.58, p = 0.06). Low levels of 25OHD were not associated with low BMD, nor were mutations in NOD2. No increased rate of fractures was seen among patients with osteopenia or osteoporosis. Conclusion: In addition to the generally accepted risk factors for osteoporosis (glucocorticoids, low BMI, smoking), male IBD patients had a trend toward lower BMD. Carrying a mutaticon in NOD2 did not confer a risk for bone loss.