Prediction of low bone mineral density in patients with inflammatory bowel diseases

Abstract

Background: Low bone mineral density (BMD) remains a frequent problem in patients with inflammatory bowel diseases (IBD). There is no general agreement regarding osteoporosis screening in IBD patients. Methods: Cases of low BMD and disease characteristics were retrieved from 3172 patients of the Swiss IBD cohort study. Multivariate logistic regression analysis was conducted for predictive modeling. In a subgroup of 877 patients, 253 dual-energy X-ray absorptiometry (DXA) scans were available for validation. Results: Low BMD was prevalent in 19% of patients. We identified seven predictive factors: type of IBD, age, recent steroid usage, low body mass index, perianal disease, recent high disease activity and malabsorption syndrome. Low BMD could be predicted with a sensitivity of 79% and a specificity of 64%, a positive predictive value (PPV) of 35% and a negative predictive value (NPV) of 93%. The area under the curve of the receiver operating characteristics was 0.78. In the validation cohort we calculated a PPV of 26% and an NPV of 88%. Conclusion: We provide a comprehensive analysis of risk factors for low BMD and propose a predictive model with seven clinical variables. The high NPV of models such as ours might help in excluding low BMD to prevent futile investigations.