Vitamin D status of severe COPD patients with chronic respiratory failure

The aim of the study was to measure the concentrations of vitamin D in serum of COPD patients with chronic respiratory failure in comparison to healthy control group. The correlation between the levels of vitamin D in serum and the selected clinical, spirometric and blood gas parameters was the additional aim of the study.

The study included 61 patients with diagnosed COPD in stadium of chronic respiratory failure (45 men and 16 women) and 37 healthy controls (19 men and 18 women). The following procedure were performed in all studied subjects: detailed history (especially: daily activity, diet, tobacco and alcohol use), post-bronchodilator spirometry, assessment of 25(OH)D in serum and for COPD group only blood gas analysis. Recruitment for the study was conducted from November to April. Statistical analysis was performed using the following statistical methods: t-Student test, Mann-Whitney U test, Spearman correlation test and Chi-kwadrat test.

There was no significant differences between COPD and control group for the levels of 25(OH)D in serum. Median and lower; upper quartile were respectively following: 24,75 nmol/l (16,9; 36,4) vs. 24,06 nmol/l (16,3; 37,2), p=0,69. Vitamin D deficiency was present in 60 COPD patients (98,3% of all patients) and in 36 control group subject (97,3% of all healthy volunteers). The difference was not statistically significant. The levels of vitamin D in serum did not significantly correlated with any of studied parameters (spirometry, blood gas, age, the level of activity, BMI, tobacco smoke exposure and others). However, the level of activity in COPD group correlated positively with spirometry values and negatively with age and number of exacerbations.

The results of the study showed that in autumn-winter time in Poland there are very frequent deficiency of vitamin D in serum not only in COPD patients in respiratory failure stage but also in elderly healthy persons. However, in contrary to expectations the deficiency of vitamin D in COPD patients with respiratory failure were similar to that seen in healthy persons.