Persistently Elevated C-Reactive Protein Levels and Low Body Mass Index Are Associated with a Lack of Improvement in Bone Mineral Density in Crohn's Disease

Background: Osteoporosis prevalence is increased in Crohn's disease (CD). Its pathogenesis in these patients is incompletely understood. Objectives: To identify factors associated with decreased bone mineral density (BMD) status in CD patients on a time-line course. Methods: A retrospective study was performed that followed CD patients who underwent at least two bone mineral density scans (DEXAs). Follow-up began one year prior to the first DEXA test and lasted at least one year after a second test. Possible correlations between baseline and follow-up variables and changes in BMD status were examined. Change in BMD was defined as a transition from one bone density category to another (normal vs. osteopenia vs. osteoporosis). Binary variables were assessed using the Cochrane-Armitage test. Categorical variables were assessed using the chi-squared test. A multivariate analysis was performed. Results: The study included 141 patients. At baseline, 33 patients (23.4%) had normal BMD, 75 (53.2%) had osteopenia, and 33 (23.4%) had osteoporosis. Patients with low BMD had a lower baseline BMI compared to those with normal BMD (p < 0.0001). After a median follow-up of 48 months (IQR 29-71), BMD status worsened in 19 (13.5%) patients, whereas in 95 (67.3%) and 27 (19.1%) patients, BMD remained unchanged or improved, respectively. On the multivariate analysis, elevated median CRP throughout follow-up (OR = 0.8, 95% CI: 0.68-0.93) and low baseline BMI (OR = 0.9, 95% CI: 0.83-0.98) were associated with a lack of BMD status improvement. Conclusions: Persistently elevated CRP and low BMI are associated with a lack of improvement in BMD. These findings underscore the importance of effective inflammation control and nutritional support to maintain and improve bone health.