ESPE Abstracts

Background: Adults with CF show a higher rate of osteoporosis compared to healthy adults. Achieving proper bone mass is a process starting in childhood. We aimed to evaluate the prevalence of decreased bone mineral density (BMD), changes during puberty and risk factors for low BMD in children and adolescences with CF in a large Dutch cohort.

Patients and methods: A retrospective observational cohort study was performed in 106 children with CF aged 8-18. Anthropometry, DEXA scan results and endocrine data were collected. BMD z-scores were adjusted for height. At risk and low BMD scores were defined as z-scores ≤ -1 and ≤ -2 respectively. We analyzed if BMD was associated with BMI-SDS, serum vitamin D values, lung function (FEV1%predicted) and presence of cystic fibrosis related diabetes (CFRD). Sixty-five of 106 patients underwent a second DXA-scan during follow-up.

Results: At the initial scan overall prevalence of low BMD values was 5.7% for lumbar spine (LS) and 3.8% for total body less head (TBLH). Mean adjusted BMD z-scores were normal (0.05 ± 1.13 and 0.14 ± 1.08 for LS and TBLH respectively). The children were well-nourished, but the range was remarkable (median (range) BMI-SDS -0.12 (-3.33 to +2.46), and had normal mean FEV1%predicted values (91.3 ± 15.6). After a mean follow-up time of 2.37 ± 0.54 yrs, significant decreases in both mean adjusted LS and TBLH BMD z-scores were found (-0.23 ± 0.67 and -0.72 ± 0.54 respectively). Female gender (β = 0.445, P= 0.001) and new onset of CFRD (β = -0.429, P= 0.003) were significant predictors for the change in adjusted TBLH BMD z-score in a multivariate model. FEV1%pred values at baseline were associated to adjusted TBLH BMD z-scores univariately (β = -0.009, P= 0.037). The change in BMI-SDS was a significant predictor for the change in adjusted LS BMD z-scores (β = 0.313, P= 0.005).

Conclusion: Although overall most children with CF have normal BMD, a significant decrease in BMD over time is seen, already during childhood and especially in boys and in those with newly onset CFRD. Optimizing nutritional status, especially in children with decreased lung function, remains important to prevent bone loss.