ISC.15: Vitamin D may predict stroke severity

Physicians, take note: Researchers may have found a link between stroke severity and vitamin D deficiency. These findings were presented Feb. 11 at the American Stroke Association’s 2015 International Stroke Conference in Nashville, Tenn.

This retrospective analysis of stroke patients with recorded vitamin D levels was presented by Nils Henninger, MD, of the University of Massachusetts Medical School in Worchester. Henninger and colleagues found that when patients were vitamin D deficient, strokes were significantly bigger. Vitamin D levels were defined using Endocrine Society definitions: less than 20 ng per ml of vitamin D was deemed deficient while 30 ng per ml was sufficient.

Henninger and colleagues, faced with other research in the field about the influence of vitamin D on health, came to ask themselves what effect it had on stroke severity. In an interview with Cardiovascular Business, Henninger said, “Vitamin D is a big topic for primary care physicians because it is believed to have impact on various stroke risk factors, (including) high blood pressure, diabetes, things like that. Also there seems to be an increasing number of studies coming out that link vitamin D to all kinds of other conditions, including, actually, neurological conditions.”

While the impact of vitamin D on stroke risk has been a topic for other studies, Henninger’s team focus revealed a nearly fourfold larger stroke by two weeks following an event in patients with low vitamin D levels. Subanalysis revealed that low vitamin D also doubled the size of both lacunar and nonlacunar strokes. Insufficient vitamin D levels also appeared to influence the distribution of outcomes, with more than two-thirds of patients with low vitamin D levels showing poorer functional status at three months.

Henninger said that an important aspect to understanding the influence of vitamin D on stroke and stroke status starts with “a biological correlate – infarct size, something I can measure in hard numbers – might give a better indication of how vitamin D might work in this whole question about why people have worse outcomes. It gives me a biological plausible foundation.”

Henninger noted that using infarct size, the team was better able to quantify outcomes related directly to the initial stroke and define initial stroke severity without including outcomes that may be unrelated, such as later death by heart failure.

The next step is to look for validation in a larger group of patients, said Henninger. After that, “We find a target population of patients who are at a high risk for stroke and supplement those with vitamin D when the targets are below a certain cut point. Can we modify that risk?

“The interesting thing is that while there are a lot of studies that show that the risk may be higher when vitamin D level is low, there are no studies as yet that show that you can reverse this effect by supplementing vitamin D,” Henninger said.