Re-evaluating osteoporosis and fracture risk in Crohn's disease patients in the era of TNF-alpha inhibitors.

Introduction: Patients with Crohn's disease (CD) are at increased risk for osteoporosis and fractures as compared to the general population. Recently, various cytokines including tumor necrosis factor (TNF)-alpha are found to play a major role in bone health. In this study, we aimed to gain a better understanding of the risk factors for osteoporosis and vitamin D deficiency in the era of TNF-alpha inhibitors.

Methods: We conducted a retrospective review of 464 consecutive patients with CD in our GI clinic between 2008 and 2015. Statistical analysis was performed using the student t-test and chi-square test.

Results: CD patients treated with TNF-alpha inhibitors (TNF) and those who are anti-TNF naïve (NB) had similar rates of vitamin D deficiency, insufficiency and normal vitamin D-25-OH levels. Similarly, rates of osteoporosis (16% vs 18%), osteopenia (53% vs 57%) and normal bone density (31% vs 25%) were comparable between the TNF and NB groups respectively. However, Z-scores at the spine (-0.47 vs -0.05) were significantly lower in the TNF group (p = .03). Interestingly, rates of osteoporosis in the NB group were drastically different before and after age 60 (3.6% vs 30%) with no major difference in the TNF group (15% vs 18%). Bone density was positively correlated with BMI (Pearson's R = 0.39) and negatively correlated with age and smoking status (R= -0.25).

Conclusions: TNF group patients were diagnosed with osteoporosis from an earlier age compared to NB group but with a smaller increase in osteoporosis after menopause. Further prospective studies are necessary to further determine the role of anti-TNF medications in osteoporosis.