The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: a multicentre retrospective study

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordBackground 25‐hydroxyvitamin D (25OHD) may exert immunomodulatory effects on respiratory health, which may translate to improvements in exercise physiology. Thus, we aimed to investigate whether plasma 25OHD is associated with lung function and aerobic fitness in people with cystic fibrosis (pwCF). Methods A multi‐centre retrospective review of pwCF (>9 years old) attending the Royal Hospital for Sick Children (Edinburgh) or Wessex CF‐Unit (Southampton) was performed between July 2017 to October 2019. Demographic and clinical data were collected. Plasma 25OHD measured closest in time to clinical cardiopulmonary exercise testing (CPET) and/or spirometry (forced expiratory volume FEV1% predicted) was recorded. Pancreatic insufficiency was diagnosed based on faecal elastase of <100 µg/g. We performed multiple‐regression analysis with aerobic fitness outcomes [peak oxygen uptake (VO2peak)] and FEV1% predicted as primary outcomes. Results Ninety pwCF [mean±SD age: 19.1±8.6 years, 54 (60%) children, 48 (53%) males and 88 (98%) Caucasian] were included. 25OHD deficiency and insufficiency was 15 (17%) and 44 (49%) respectively. 25OHD deficiency and insufficiency was significantly associated with pancreatic insufficiency (χ2(4.8); p = 0.02). Plasma 25OHD was not significantly associated with FEV1% predicted [R2 = 0.06; p= 0.42; 95%; CI (‐0.09 ‐ 0.19)] or VO2peak [R2= 0.04; p= 0.07; 95% CI (‐011 ‐ 0.005)] in all pwCF. However, 25OHD was significantly associated with both FEV1% [R2= 0.15; p= 0.02; 95% CI (1.99 ‐ 2.64)] and VO2peak [R2= 0.13; p= 0.05; 95% CI (‐0.26 – (‐0.005)] in the paediatric cohort. Conclusion We showed that 25OHD is associated with improved lung function and aerobic fitness in children and adolescents with CF. Mechanistic and high‐quality prospective studies including both lung function and aerobic fitness as primary outcomes are now warranted.NHS Lothian Research and Development Offic

The implications of dysglycaemia on aerobic exercise and ventilatory function in cystic fibrosis

BACKGROUND: The development of cystic fibrosis (CF)-related diabetes (CFRD) in paediatric groups is associated with a reduced aerobic fitness. However, this has yet to be investigated in adults with more severe lung disease.METHODS: Cardiopulmonary exercise and glycaemic control tests were retrospectively analysed in 46 adults with CF (age: 26.9 y [range: 16.3-66.5 y]; forced expiratory volume in 1s: 65.3% [range: 26.8-105.7%]; 26 males), diagnosed with CFRD (n = 19), impaired glucose tolerance (IGT; n = 8) or normal glucose tolerance (NGT; n = 19).RESULTS: Maximal oxygen uptake (V˙O2max) was reduced in adults with IGT and CFRD compared to their age- and gender-matched counterparts with NGT (p &lt; 0.05); however, there was no difference when lung function was included as a covariate (all p &gt; 0.05). V˙O2max was greater in adults who experienced post-reactive hypoglycaemia vs. NGT without hypoglycaemia (p &lt; 0.05). The frequency of ventilatory limitation (84%, 63% and 37%, respectively; p &lt; 0.05) but not ventilation-perfusion mismatch (42%, 38% and 16%, respectively; p &gt; 0.05), was greater with CFRD and IGT vs. NGT. There was also no difference in arterial oxygen saturation changes between groups (p &gt; 0.05). Gender and body mass index were significant predictors of V˙O2max (adjusted R2 = 0.37, p &lt; 0.01), but glycaemic control did not explain additional variance (p &gt; 0.05).CONCLUSIONS: Adults with CF-related dysglycaemia had a reduced V˙O2max compared to age- and gender-matched counterparts, due to a greater degree of CF lung disease in these populations.</p