AIM: The influence of vitamin D on COPD is still a matter of debate. In a cohort of COPD subjects we investigated the association between serum level of vitamin D and markers of systemic inflammation, exacerbation frequency, COPD symptoms, lung function and co-morbidity.

METHODS: Caucasians (n =111) in a stable phase of COPD were investigated using spirometry and blood analysis. CAT was used to assess COPD symptoms and co-morbidity was graded by Charlson Co-morbidity Index. All subjects were defined as frequent exarcebators, with ?2 exacerbations per year, during the year prior to inclusion. Subjects with on-going medication or supplementation affecting the vitamin D or calcium metabolism were excluded.

RESULTS: Subjects with low levels (?50 nmol/L) of the stable metabolite of vitamin D, 25(OH)D, demonstrated significantly more exacerbations, COPD symptoms and raised levels of hs-CRP (p ?0.001) than subjects with high levels. The level of 25(OH)D was negatively associated with the exacerbation frequency, the level of hs-CRP (p ?0.001) and CAT-points (p ?0.01). The level of 25(OH)D demonstrated no association with FEV1 % of predicted. The GOLD class I-IV did not differ regarding the level of 25(OH)D. Co-morbitity devided into groups by their CCI-points demonstrated no significant difference regarding the levels of 25(OH)D.

CONCLUSIONS: Present study implies a link between vitamin D metabolism and exacerbation frequency and systemic inflammation in COPD subjects with the phenotype prone to frequently exacerbate. This supports GOLD 2023 proposal to analyse vitamin D level of all COPD patients hospitalised for exarcebations followed by supplementation if required.