Prevalence of bone loss in a population with cystic fibrosis

The adverse effect of an increased life expectancy for people with cystic fibrosis (CF) is the increased risk of complications, such as CF-related low bone mineral density (BMD). Diagnosis of CF-related low BMD is confirmed by a dual-energy X-ray absorptiometry (DXA) scan. This study reports the results of an audit of DXA scans in 108 adults with CF in our clinic. The most common risk factors for bone loss were vitamin D deficiency (89%), CF-related diabetes (53%), low body mass index (39%) and post-lung transplant (25%); half of those with bone loss were genotype homozygous DF508. Overall fracture incidence was 5.5%; low BMD was not associated with high fracture rates. Thus BMD may not be a good predictor of fracture risk. Treatment includes bisphosphonates, which are difficult to take and have uncertain long-term effects. It is unknown whether bisphosphonate therapy is justified in this already overburdened group.