Risk factors for low bone mass in patients with ulcerative colitis following ileal pouch-anal anastomosis.

ABSTRACT

OBJECTIVES: Bone mineral density (BMD) can be adversely affected by the chronic nature of inflammatory bowel disease. Ileal pouch-anal anastomosis (IPAA) is the surgical treatment of choice for patients with ulcerative colitis (UC) who require proctocolectomy. There are few data on BMD in UC patients with IPAA. The aim of the study was to assess the prevalence and risk factors associated with low BMD in UC patients after IPAA. METHODS: A total of 327 eligible patients with UC and IPAA from the Pouchitis Clinic were enrolled. Dual-energy X-ray absorptiometry was performed. Patients were classified as having normal or low BMD, based on the criteria by the International Society for Clinical Densitometry. A total of 39 demographic and clinical variables were evaluated with logistic regression models. RESULTS: Of 327 patients with a median of 4 years after IPAA, 105 (32.1%) had low BMD. Fragility fracture was documented in 11 patients (10.5%) in the low BMD group and in 13 of 222 patients (5.9%) in the normal BMD group (P=0.14). In the multivariable analysis, covariate-adjusted factors associated with a low BMD were advanced age (odds ratio (OR) =1.64 per 5 years; 95% CI, 1.44-1.87), low body mass index (OR=0.43 per 5 kg/m(2); 95% CI, 0.30-0.62), and non-use of daily calcium supplement (OR=0.53; 95% CI, 0.29-0.96). Pouch-associated factors were not found to be significantly associated with the bone loss. CONCLUSIONS: Low BMD was common in patients with UC, even after colectomy and IPAA. Low BMD in this patient population was associated with certain risk factors, some of which may be modifiable.