We read with great interest van Bodegraven et al's1 paper about the treatment of osteopenia in patients with Crohn's disease. They have identified an evidence gap, as many studies of interventions to treat osteoporosis and prevent bone loss have been conducted on older and primarily female patients. In contrast, both male and female patients with Crohn's disease may develop osteopenia and osteoporosis at a younger age. The authors found that use of risedronate can improve bone density in the lumbar spine of patients with Crohn's disease.

One of the exclusion criteria for patients in this study was vitamin D deficiency. Vitamin D deficiency has previously been noted to be common in patients with Crohn's disease.2 Vitamin D deficiency in patients with Crohn's disease has been known to correlate with bone loss for some time.3 Patients with Crohn's disease who are vitamin D deficient may be those at greatest risk of bone loss. The decision to exclude these patients is one of the major limitations of this work, as vitamin D-deficient patients with osteopenia are also the group that could benefit the most from bisphosphonate treatment.

While van Bodegraven et al demonstrated an improvement in bone density, a surrogate marker for fracture risk, their paper was not powered to and did not follow up for long enough to detect a difference in fracture rate. Although many other similar studies have also used bone density as a surrogate marker, on the basis of this work, further studies should aim to detect a difference in fracture risk, which is a more clinically important outcome.

Given that patients with Crohn's disease are at a substantially higher risk of a fracture than age-matched controls,4 the work of van Bodegraven et al suggests that risedronate may have merit in improving the bone density and preventing fractures in relatively young patients with Crohn's disease.