Children and young adults with CF in the USA have better lung function compared with the UK.

BACKGROUND: People with cystic fibrosis (CF) are managed differently in the USA and UK providing an opportunity to learn from differences in practice patterns. OBJECTIVES: To compare cross-sectional demographics, practice patterns and clinical outcomes between US and UK CF patients. METHODS: This was a cross-sectional study using 2010 data from patients in the US Cystic Fibrosis Foundation and the UK Cystic Fibrosis patient registries. The a priori outcome measures of interest were lung function and nutritional status. Descriptive statistics and two sample comparisons were performed. Stratification and multivariable linear regression were used to adjust for confounding. RESULTS: The study cohort included 13 777 children and 11 058 adults from the USA and 3968 children and 3965 adults from the UK. In children, mean body mass index centiles were similar. Lung function (FEV1 and FVC% predicted) was significantly higher in US patients ages 6-25 years of age. In a regression model adjusted for only age, FEV1% predicted was on average 3.31% of predicted (95% CI 2.65 to 3.96) higher in the USA compared with the UK. When adjusted for age, age at diagnosis, gender, pancreatic insufficiency and genotype, FEV1% predicted was on average 3.03% of predicted (95% CI 2.37 to 3.69) higher in the USA compared with the UK These differences persisted despite adjustment for possible confounders. Hypertonic saline and dornase alfa were much more commonly prescribed in US children. CONCLUSIONS: Children and young adults with CF have better lung function in the USA compared with the UK despite similar nutritional status.

The impact of switching to the new global lung function initiative equations on spirometry results in the UK CF registry.

BACKGROUND: The Quanjer et al. Global Lung Function Initiative (GLI)-2012 multi-ethnic all-age reference equations for spirometry are endorsed by all major respiratory societies and are the new gold standard. Before the GLI equations are implemented for use in CF patients, the impact of changing equations from those currently used needs to be better understood. METHODS: Annual review data submitted to the UK CF Trust Registry between 2007 and 2011 were used to calculate %predicted FEV1, FVC and FEV1/FVC using three widely used reference equations (Wang-Hankinson and Knudson) and the new GLI-2012 equations. RESULTS: Overall, Knudson and Wang equations overestimated %predicted values in paediatric patients, such that a greater proportion of patients had lung function values in the normal range. Within individual patients, the impact of switching equations varied greatly depending on the patients' age, and which equations were used. CONCLUSIONS: A unified approach to interpreting spirometric lung function measurements would help facilitate more appropriate comparison both within and between centres and countries. Interpretation of longitudinal measurements using a continuous reference equation across all-ages, like the GLI, may further improve our understanding of CF lung disease.

Osteoclastogenesis during infective exacerbations in patients with cystic fibrosis.

RATIONALE: Adults with cystic fibrosis (CF) are at increased risk of developing osteoporosis. During infective exacerbations, increased production of proinflammatory cytokines and markers of bone resorption have been reported. OBJECTIVE: The aim of this study is to investigate the growth and proliferation of potential osteoclast precursor cells before, during, and after intravenous antibiotic treatment of infective exacerbations in patients with CF. METHODS: Hematopoietic precursor cell growth was examined using colony formation assays using Methocult culture medium. Circulating potential osteoclast precursors were identified using four-color flow cytometry by CD14, CD33, CD34, and CD45 expression. RESULTS: At the start of an infective exacerbation increases in hematopoietic precursor colony formation (15.42 colonies/10(5) cells plated, p = 0.025), proliferation (28.5%, p < 0.001), and the numbers of circulating potential osteoclast precursors (6.5%, p < 0.001) were seen in comparison with baseline levels. These increases declined after treatment with intravenous antibiotics to a level close to baseline. CONCLUSIONS: The results demonstrate an increase in the production of potential osteoclast precursors in the peripheral blood during CF infective exacerbations. This may result in increased bone resorption and contribute to bone loss in patients with CF.