ICU patients and Vitamin D deficiency-new NEJM study

New New England Journal of Medicine article on relation between outcomes in critial care units and Vit D status at entry. "Vitamin D Deficiency in Critically Ill Patients,".
Correlation or Causation? Very sick patients in ICUs do worse when they are vitamin D deficient. But is Vit D deficiency a cause of bad outcomes or a marker of worse illness? That is the question at this point. Would that we had an NIH that would fund large-scale controlled trials Vitamin D supplementation as preventive and therapy. But, Vit D is cheap and a commodity, so there's no commercial interest to push for studies or to fund them.
In the meantime, knowing your Vit D status and supplementing to get it up into the mid-range of normal -- say, shoot for 50 -- cannot hurt.