Prevalence of vitamin D deficiency prior to cardiothoracic surgery

Vitamin D deficiency is one of the most common chronic medical conditions in the world and also prevalent in Australia. A growing body of evidence suggests that low vitamin D also has adverse effects on cardiovascular health, including coronary risk factors and adverse cardiovascular outcomes such as myocardial infarction, cardiac failure and stroke. There is some evidence suggesting that a greater proportion of people with cardiovascular disease have low vitamin D compared to the general population. We examined the prevalence of vitamin D deficiency and insufficiency in elective cardiothoracic surgical patients presenting to the Alfred Hospital in Melbourne, Australia and compared this to recent Victorian statistics for people of the same age group.

Consecutive adult elective cardiothoracic surgical patients listed for either coronary artery bypass graft surgery or heart valve repair or replacement surgery attending The Alfred Hospital, Melbourne between July 2011 and October 2012 were invited to participate. This ensured that patients were enrolled over all four seasons. Fasting serum samples were taken on the day of surgery, immediately after admission. Eighty volunteers participated in the study. Of the group, 40% were due to have coronary artery bypass graft surgery, 35% valve surgery and 25% a combination of the two; 74% reported having hypertension, 69% hyperlipidaemia, 26% diabetes and 39% had a BMI >30 kg/m(2).

Test results revealed that 92.5% of patients had Vitamin D levels < 75 nmol/L, 67.5% had levels < 60 nmol/L, 52.5% had levels between 30-59 nmol/L and 15% had levels < 30 nmol/L. Inadequate vitamin D levels were found in 80% of obese patients (BMI > 30 kg/m(2)) compared to 59% of non-obese patients.

Based on our small screening study, a substantial proportion of elective cardiothoracic surgical patients have less than optimal serum vitamin D3 levels prior to surgery. We found two-thirds of patients had serum vitamin D levels below 60 nmol/L, placing them at higher risk of falls. This finding is of concern as these patients would have received multiple consultations with various medical practitioners prior to hospital admission and yet their inadequate vitamin D status remained. Failing to identify patients with low vitamin D and correcting it with supplementation places older adults at unnecessary risk, especially of falls, which are associated with a high risk of mortality. In an ageing population with CVD, vitamin D status needs to be assessed and any inadequacy corrected. Whether low vitamin D status prior to cardiac surgery affects post-surgery outcomes, is another issue which deserves future investigation.