However, our data showed a signific

However, our data showed a significant independent association
between depression and lower levels of vitamin D in COPD
patients. To our knowledge this has not been previously reported
in COPD patients. Whether this is caused by factors such as less
physical activity, less time spent outdoors and change in diet we
cannot say from the current study. Longitudinal studies, taking
these potential confounders into account, are necessary to address
this important issue.