Patients with low blood levels of vitamin D are at increased risk of death and serious complications after non-cardiac surgery, suggests a recent study published in Anesthesia & Analgesia.
A team led by Alparslan Turan of the Cleveland Clinic analysed the relationship between vitamin D level and surgical outcomes in approximately 3500 patients who underwent operations other than heart surgery between 2005 and 2011. Only patients who had available data on vitamin D levels around the time of surgery – from three months before to one month afterward – were included in the study.
The concentration of 25-hydroxyvitamin D in blood samples was analysed as a risk factor for death, cardiovascular events or serious infections while in hospital. The analysis included adjustment for other factors such as demographics, medical conditions, and type and duration of surgery.
Most patients did not meet the recommended 25-hydroxyvitamin D concentration of greater than 30ng per ml. More than 60% of patients were in the range of vitamin D insufficiency (10 to 30ng/ml), while nearly 20% had vitamin D deficiency (less than 10ng/ml).
“Higher vitamin D concentrations were associated with decreased odds of in-hospital mortality/morbidity,” said Turan. For each 5ng/ml increase in 25-hydroxyvitamin D level, the combined risk of death, cardiovascular events, or serious infections decreased by 7%.
Patients at the lowest level of 25-hydroxyvitamin D (less than 13ng/ml) were at highest risk of death or serious complications. Those with higher vitamin D levels (up to 44ng/ml) had about half the risk of those in the lowest group. The association with low vitamin D was statistically significant only for cardiovascular complications, although there were “strong trends” for mortality and infections.
Further study needed to determine cause and effect
In addition to protective cardiovascular and neurological effects, vitamin D plays an important role in the immune system. The high rates of vitamin D insufficiency and deficiency in the surgical patients studied are consistent with previous findings in the general population. In recent years, studies have suggested that vitamin D levels may affect a wide range of health outcomes.
Turan and colleagues suggest a formal randomised trial to evaluate whether preoperative vitamin D supplementation can reduce the risk of serious complications and death after surgery.
Turan, A., et al. (2014) Anesthesia & Analgesia 119(3), 603–612