Risk factors for osteoporosis in Crohn's disease: infliximab, corticosteroids, body mass index, and age of onset.

BACKGROUND: We analyzed the characteristics associated with increased risk of osteoporosis in patients with Crohn's disease in Malta.
METHOD: Eighty-three patients with histologically and endoscopically confirmed Crohn's disease underwent a DEXA bone density scan and their phenotypic characteristics were analyzed.
RESULTS: There was a significant association between body mass index and bone mineral density (P = 0.004) and a significant difference in the T scores of patients according to age at diagnosis (Montreal Classification: P = 0.0006) with patients diagnosed <17 years (n = 13) having lower T scores than those diagnosed at older age groups (n = 70). There was a significant difference between the T scores of patients on infliximab (n = 33) and those not on biological therapy (n = 50, P = 0.0058). Patients with high cumulative corticosteroid doses (>10 mg/d for >3 mo, n = 18) had lower bone mineral densities than patients who received smaller corticosteroid doses (P = 0.013). There was however no significant difference in the T scores of patients according to disease location (P = 0.18), disease type (P = 0.64), gender (P = 0.30), and history of ileal resection (P = 0.68). There was also no significant correlation between disease duration and T scores (hip) (P = 0.61).
CONCLUSIONS: Low body mass index, early disease onset, high corticosteroid doses and, anti-tumor necrosis factor α therapy are associated with increased risk of osteoporosis. Lower T scores in patients on infliximab occur as patients receiving this therapy have more severe inflammation, which is associated with elevated osteoclastogenic factors, rather than as a side-effect of the anti-tumor necrosis factor-α therapy.