Objective: In Crohn's disease, osteoporosis is frequently found. However, the etiology of osteoporosis remains unclear. The aim of this study was to determine disease-related variables predictive for impaired bone mineral density (BMD).
Methods: A total of 91 patients with Crohn's disease who were admitted for BMD assessment were enrolled in the study. BMD was measured at the femoral neck and lumbar spine by dual energy x-ray absorptiometry (DXA). Results were expressed as T-score and as age- and sex-matched Z-score. Data were obtained by a questionnaire and from patients' medical records. Stepwise linear regression analysis was used to determine independent variables predictive for BMD.
Results: Mean age at BMD assessment was 41 +/- 12 yr, duration of disease 11.6 +/- 8.5 yr, and body mass index (BMI) 23.0 +/- 4.1 kg/m2. The cumulative dose of steroids used was 18.7 +/- 19.2 g. Mean Z-scores were less than zero (spine, -1.1 +/- 1.3 SD; femur, -1.1 +/- 1.2 SD; p < 0.0001). A total of 27 patients (30%) fulfilled the World Health Organization criteria for osteoporosis and 46 patients (50%) for osteopenia. Osteoporotic patients used more corticosteroids and had longer duration of disease, lower BMI, and more bowel resections than patients with normal BMD. However, in the linear regression analysis, the only significant independent predictors for BMD of the lumbar spine and femoral neck were BMI and history of bowel resections. BMI and history of resections together accounted for 28% of BMD Z-scores.
Conclusions: BMI and a history of bowel resections were significant predictive variables for BMD. Despite the high dose of steroids used in this study, no detrimental effect could be demonstrated as independent predictor for osteoporosis.