P617 Persistent active inflammation may predict non-improvement in bone mass density in patients with Crohn's disease

Abstract

Abstract Background Osteopenia and osteoporosis are associated with Crohn’s disease (CD). Diagnosis is made by dual-energy X-ray absorptiometry scan (DEXA). Pathophysiology of osteoporosis may reflect an interplay between persistent inflammation, steroid usage, as well as risk factors similar to general population. We aimed to identify factors associated with low or deteriorating bone mineral density (BMD) among patients. Methods A retrospective case-control study, included patients with CD followed at our IBD clinic from January 2000 to February 2023, with ≥ 2 DEXA scans. The observation started one year before the initial DEXA scan and extended until one year after the second scan. Demographic, clinical and laboratory data as well as medication exposure were collected before and during F/U. Patients were classified into three groups based on change in DEXA results: improved, worsened and no change. Multivariable proportional odds regression model was built to assess independent predictors of change in BMD. Results 121 patients [60 (49.6%) females, median age 33 years (IQR 23-43), median disease duration 5 years (IQR 0-35), median baseline BMI 22.4 kg/m2 (IQR 12.9-39.3), baseline CRP 1.4 ULN (IQR 0.5-4.5), baseline vitamin D 54.2 nmol/L (IQR 40.9-67.5)], were enrolled and followed for a median of 48 (IQR 29-71) months. At baseline, patients with osteoporosis had a lower BMI (18.5 kg/m2) than patients with normal BMD (26 kg/m2) and osteopenia (22.4 kg/m2), p<0.001. During F/U 63%, 59% and 66% of patients were exposed to high dose CS, anti-TNF and thiopurines respectively. At the end of F/U,19 (15.7%) patients had deterioration in BMD status while 78 (64.5%) remained unchanged, and in 24 (19.8%) BMD improved. Baseline vitamin D levels (in nmol/L) were higher in patients with improvement in BMD status at the end of the F/U compared to those with maintained or deterioration in BMD (66, 54.2, 41.2; p=0.001, Figure 1). Active smoking was associated with decline in BMD status (p=0.03). No correlation was found between different types of medication exposure and changes in BMD status. In multivariable analysis, elevated CRP was the only independent variable associated with lower odds of improvement in BMD (OR=0.45 (CI 0.2-1.0), p=0.05,Table 1). Conclusion Low BMI, low baseline vitamin D levels, and active smoking were found to be risk factors for low BMD status. Elevated CRP was associated with lack of improvement in BMD during the F/U. No correlation was found between different medications and changes in BMD status.