INFLAMMATORY BOWEL DISEASE AND THE RISK OF FRACTURE
Patients with inflammatory bowel disease (IBD) have an increased risk of low bone mass, the pathogenesis of which is multifactorial. There are limited data on fracture. We therefore conducted a primary care based case-control study to determine the risk and major risk factors of fracture in IBD patients. 231 778 patients with a fracture and 231 778 age and sex matched controls were recruited from the General Practice Research Database. The database has been previously demonstrated to be a representative sample of the general population of England and Wales. Adjusted odds ratios (OR) were estimated from conditional logistic regression. The mean age of cases and controls was 51 years and 52.5% were women. A history of IBD was found in 1134 fracture cases, compared with 896 of the controls (adjusted OR 1.21; 95% CI 1.10 to 1.32). The OR was 1.72 (1.13-2.61) for vertebral fracture and 1.59 (1.14 to 2.23) for hip fracture. The risk of fracture was greater in patients with a history of Crohn's disease (OR 1.32 (1.13-1.53)) than in patients with ulcerative colitis (OR 1.13 (1.02-1.27)). The risk of fracture in patients with a history of IBD was significantly related to disease severity as assessed by the number of symptoms (OR in IBD patients without symptoms, 1.02 (0.90-1.17); 1 symptom, 1.66 (1.41-1.96); and 2 symptoms, 1.74 (1.43-12.12)). Similarly, severity assessed by medication demonstrated increasing fracture risks compared with untreated patients: aminosalicylates use 1.32 (1.14-1.54), oral corticosteroids 1.46 (1.18-1.82), and steroid sparing agents 1.86 (1.15-3.02). IBD patients with a history of bowel surgery did not have an increased risk of fracture (OR 1.03 (0.84-1.28)). Use of oral corticosteroids increased with severity of disease; after adjustment for oral corticosteroid use the risk of hip fracture remained elevated (OR 1.46 (1.04-2.04)). In conclusion, IBD patients have a higher risk of fractures, which is due to a combination of disease activity and oral corticosteroid use.