Vitamin D deficiency increases risk of 'silent' cardiovascular disease in HIV-positive African Americans

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Vitamin D deficiency is associated with “silent” coronary artery disease, according to the results of a study involving HIV-positive African Americans published in the online edition of Clinical Infectious Diseases. Other risk factors included high blood pressure, long-term cocaine use and antiretroviral therapy.

“The study found that among cardiovascularly asymptomatic African Americans with HIV infection, vitamin D deficiency was independently associated with a greater than two-fold increase in the risk of the presence of significant coronary stenosis [narrowing of the blood vessels],” comment the authors.

African Americans have a high prevalence of coronary artery disease. The exact causes are uncertain and traditional risk factors do not appear to account for all this increased risk.

Glossary

CAT scan

A computerised axial tomography (CAT) or computed tomography (CT) scan is a type of specialised X-ray that gives a view of a 'slice' through the body, and is used to help detect tumours, infections and other changes in anatomy.

asymptomatic

Having no symptoms.

cholesterol

A waxy substance, mostly made by the body and used to produce steroid hormones. High levels can be associated with atherosclerosis. There are two main types of cholesterol: low-density lipoprotein (LDL) or ‘bad’ cholesterol (which may put people at risk for heart disease and other serious conditions), and high-density lipoprotein (HDL) or ‘good’ cholesterol (which helps get rid of LDL).

cardiovascular

Relating to the heart and blood vessels.

It is therefore significant that a number of recent studies have suggested a relationship between vitamin D deficiency and an increased risk of coronary artery disease.

Vitamin D deficiency is highly prevalent in African Americans. As HIV-positive African Americans have an especially increased risk of coronary disease, investigators from Johns Hopkins University designed a study to assess a possible relationship between this illness and vitamin D deficiency.

A total of 674 HIV-positive African Americans adults were recruited to the study, which ran between 2003 and 2011. None had diagnosed coronary artery disease.

The patients had a blood test to monitor their vitamin D levels, and CT scans were performed to measure coronary stenosis.

Most of the patients (64%) were men and their median age was 46 years. The median vitamin D level was 17.0 ng/dl. The prevalence of vitamin D deficiency (below 10ng/dl) was 20%. The vast majority of patients were assessed as having a low ten-year risk of cardiovascular disease. 

The CT scans revealed that 10% of patients had significant coronary stenosis. “This rate is high, considering that almost 90% of the population was at a low risk based on Framingham risk score,” comment the authors.

Prevalence of coronary stenosis among patients who had used HIV therapy for less than six months was 6%. It was 11% among those who had used HIV therapy for over six months. Prevalence of silent coronary artery disease among patients who had been taking antiretroviral therapy for over six months and who had vitamin D deficiency was 16%.

The prevalence of coronary stenosis also differed according to cocaine use. It was 8% among those who had never used the drug or had taken it for less than 15 years. Prevalence was 13% among longer-term cocaine users, and was 19% among patients with 15 years or more of cocaine use and vitamin D deficiency.

Overall 8% of patients who were not vitamin D deficient had narrowing of the coronary artery compared to 15% of those who had vitamin D deficiency.

The single most important risk factor for coronary stenosis was vitamin D deficiency, which more than doubled the risk of this manifestation of silent cardiovascular disease (aOR = 2.28; 95% CI, 1.23-4.21). The next most important risk factor was HIV therapy lasting over six months (aOR = 2.26; 95% CI, 1.17-4.36).

“Our findings suggest that vitamin D deficiency is independently associated with the presence of significant coronary stenosis,” write the authors. “To our knowledge, this is the first study to examine whether vitamin D deficiency is associated with silent coronary artery disease in cardiovascularly asymptomatic African American adults with HIV infection.”

A number of traditional risk factors were also significant. These included male gender (aOR = 2.19; 95% CI, 1.17-4.10), diastolic blood pressure above 85 mmHg (aOR = 1.94; 95% CI, 1.02-3.68), LDL-cholesterol above 100 mg/dl (aOR = 1.95; 95% CI, 1.13-3.36) and cocaine use for over 15 years (aOR = 1.77; 95% CI, 1.01-3.10).

“Our results further underscore the need for aggressive interventions directed towards these important risk factors,” comment the investigators.

They conclude, “as compared with identifying and successfully managing some traditional risk factors for coronary artery disease, including cigarette smoking cessation, and maintaining optimal blood pressure control, vitamin D deficiency may be much easier to screen for and treat.”

References

Lai H et al. Vitamin D deficiency is associated with silent coronary artery disease in cardiovascularly asymptomatic African Americans with HIV infection. Clin Infect Dis, online edition. DOI: 10.1093/cid/cis306, 2012 (click here for the free abstract).

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