Could a vitamin D deficiency cause a combined long-term FEV1 and bone mineral density deterioration in female asthmatics?

Objective. We already know that asthma is associated to osteoporosis/ osteopenia and characterized by an accelerated lung function decline. Our study aimed at assessing whether lung function decline and bone mineral density (BMD) deterioration in time were associated in a group of female long-standing asthmatics. We also tried to understand whether these two aspects were related to ICS treatment and vitamin D levels. Methods. 35 female asthmatics were retrospectively analysed. Results of methacholine challenge test at asthma onset, FEV1%, bone density scan at moment of recruitment and after at least 5years later were considered. Results. A significant positive relationship between femoral-tscores changes and FEV1 decline was found after a median follow-up time of 7 [6-9] years (r=0.43;p=0.04). Femoral-t-score variations and vitamin D values were also significantly related (r=0.669;p=0.024). Furthermore, we found that FEV1 decline was worse in subjects with lower vitamin D levels (-57.5[-80.4-35.9]ml/year), compared to those with normal vitamin D rates (12[-16-23.6]ml/year;p=0.055). Femoral/ vertebral t-score changes, as well as FEV1, decline were not associated to the use of medium/high ICS doses when compared to subjects treated with low ICS dosages. Conclusion. FEV1 decline and BMD deterioration in time observed in a group of female asthmatics were associated; low vitamin D levels may be the link.