Low Bone Mineral Density (BMD) is highly prevalent in adults with cystic fibrosis (CF) and is associated with increased fracture rates. We sought to establish how BMD changes with time in adults with CF and to determine what factors influence this change.
A retrospective analysis of interval bone densitometry using Dual Energy X-ray Absorptiometry (DXA) scanning in 86 adults with CF was undertaken. The patients' case notes were examined and age, body mass index, spirometry, and medications used at the point of last hospital contact were recorded.
Eighty-six patients (42 female, 44 male, mean age 27.6+/-6.7 years) had baseline and follow-up DXA scans with a mean interval between scans of 19.2+/-7.1 months. At the lumbar spine the mean BMD at baseline was 0.832g/cm2, T score -2.1 and mean follow-up BMD was 0.844g/cm2, T score of -2.0. BMD increased by a mean of 1.37% (95%CI 0.16 to 2.59, p<0.04). There were no significant changes in BMD at the femur. Regression analysis indicated that the only variable associated with an increase in BMD was the use of bisphosphonates (p<0.001). In those on bisphosphonates (25 on Alendronate and 14 on Risedronate) T scores, averaged at the femur and lumbar spine, increased from -2.2 to -2.0 (95% CI for difference 0.02 to 0.25, p<0.02), and did not change significantly in those not on bisphosphonates. The mean change in BMD, averaged at the femur and lumbar spine, in the group on bisphosphonates was +2.74% and in the group not on bisphosphonates was -0.75% (95% CI for difference 1.39 to 5.60, p<0.003).
In this study of adults with CF the only factor found to be associated with an increase in BMD was the use of oral bisphosphonates. This appears to reverse the accelerated decline in BMD seen in CF.
22 - 24 Mar 2004
British Endocrine Societies