New research published in The American Journal of Medicine has found an increased risk of all-cause mortality for patients entering the hospital with low vitamin D levels.
Past research has found a relationship between low vitamin D and increased risk of all-cause mortality. Whether the same holds true in the hospital setting is currently unknown. Since vitamin D likely plays a beneficial role in a wide variety of functions, the researchers theorized that there would be a relationship in the hospital setting.
Here in this study, the researchers, led by Dr Nancy Lange, developed a 23,603 person cohort from the Research Patient Data Registry, a computer registry that collects patient data from two Boston area hospitals. In their cohort, the researchers included people that were admitted to the hospital for a variety of reasons and had a vitamin D level drawn between 7 and 365 days prior to hospital admittance.
The researchers were primarily interested if vitamin D levels were associated with risk of mortality after 30 days of admittance. They also wanted to see if vitamin D levels correlated at all with in-hospital mortality or risk of bloodstream infections. Here is what they found:
- The mean 25(OH)D was 27.9 ng/ml.
- Those with levels greater than 30 ng/ml were least likely to die within 30 days of admittance. The odds of mortality for people with levels between 15-30 ng/ml were 1.3-fold higher, and 1.5-fold higher for people with levels less than 15 ng/ml, after adjustment for confounders.
- Those with levels greater than 30 ng/ml were least likely to die at the hospital, too. The odds of mortality for people with levels between 15-30 ng/ml were 1.4-fold higher, and 1.8-fold higher for people with levels less than 15 ng/ml, after adjustment for confounders.
- In a sub analysis, those with levels less than 15 ng/ml carried a 1.3 increased risk of acquiring an infection in the hospital compared to those with levels over 30 ng/ml.
All of these findings were statistically significant. The researchers concluded,
“In aggregate, these data demonstrate that pre-hospital 25(OH)D of less than 15 ng/ml is strongly associated with the odds of death and bloodstream infection in hospitalized patients.”
The researchers have no clear explanation for their findings, other than in previous studies, vitamin D has shown to have a beneficial role a variety of different areas, including keeping inflammation down, improving immunity, helping the respiratory system, the cardiovascular system and more.
However the study does have limitations. It is a cohort-type study, so it is not designed to prove that low vitamin D causes an increase in mortality. Rather, it is designed to show an association and help guide future research in this realm. Specifically, a randomized controlled in the future will provide better insight.
In the meantime, it appears that having a level over 30 ng/ml is associated with better mortality outcomes in the hospital setting, compared to lower levels.
Lange N et al. Pre-hospital Vitamin D Concentration, Mortality, and Bloodstream Infection in a Hospitalized Patient Population. The American Journal of Medicine, 2013