HIV-positive African Americans with low vitamin D had more than a doubled risk of coronary artery disease in a study of 674 men and women in Baltimore, Maryland.1 Other traditional risk factors also raised the odds of coronary artery disease in these people, including high blood pressure, high low-density lipoprotein (LDL) cholesterol, and cocaine use.
As HIV-positive people live longer thanks to antiretroviral therapy, heart disease -- including coronary artery disease -- has become a more frequent cause of sickness and death. Traditional heart risk factors play a big role in higher heart disease rates among people with HIV. Taking certain antiretrovirals and HIV infection itself have also been linked to a higher risk of heart disease.
Some recent research suggests that low vitamin D levels may raise the risk of coronary artery disease.5 Vitamin D levels are often low in African Americans, partly because dark skin blocks the type of sunlight that helps make vitamin D in the body. Poor diet may also contribute to low vitamin D levels. African Americans have a higher death rate from coronary artery disease than other racial and ethnic groups in the United States.
Researchers in Baltimore planned this study to analyze the impact of vitamin D deficiency (low levels) and other heart risk factors on coronary artery disease in HIVpositive African Americans without known coronary artery disease or physical signs or symptoms of coronary artery disease.
The study involved 674 African-American adults in Baltimore who did not have coronary artery disease or symptoms of coronary artery disease. Everyone was 25 years old or older. The study did not include pregnant women or people with poor kidney function indicated by a glomerular filtration rate at or below 60 mL/min/1.73m2.
Study participants were interviewed to determine drug-use behavior, smoking habits, and other factors that may affect risk of coronary artery disease. Researchers measured everyone's lipids (blood fats), blood pressure, and vitamin D levels. Participants underwent computed tomography angiography, a scanning technique that creates a picture of coronary artery narrowing caused by build-up of plaques. The researchers defined significant coronary artery narrowing as 50% or greater narrowing.
The investigators used standard statistical methods to identify factors associated with significant coronary artery narrowing regardless of what other risk factors a person might have.
The study group included 427 men (63%) and 247 women (37%). Median age was 46 years. Study participants had taken antiretrovirals for a median of 25 months. Median time on protease inhibitors stood at 5.5 months, while few study participants had used nonnucleoside reverse transcriptase inhibitors. The group had a median CD4 count of 329 when the study began.
Median blood pressure stood at 117/73 mm Hg, below a target healthy blood pressure of 120/80 mm Hg. According to the Framingham score, which estimates heart disease risk, 355 of 427 men (83%) and 230 of 247 women (93%) had a low risk of coronary artery disease.
Median vitamin D level in study participants was 17 ng/mL. There were 135 people (20% of the study group) with vitamin D deficiency, defined as a level below 10 ng/mL. Among people whose vitamin D level was above 10 ng/mL, 7.7% had significant coronary artery narrowing. In contrast, 14.9% with a vitamin D level below 10 ng/mL had significant narrowing.
While 5.9% of people taking antiretrovirals for fewer than 6 months had significant coronary artery narrowing, 11.2% of those taking antiretrovirals for more than 6 months had significant narrowing. Rates of significant coronary artery narrowing were 7.7% in those who never used cocaine or used cocaine fewer than 15 years versus 12.5% in those who used cocaine for 15 years or more.
Statistical analysis that considered many coronary artery disease risk factors found seven factors that raised the risk of significant coronary artery narrowing regardless of whatever other risk factors a person had (Figure 1). A vitamin D level below 10 ng/mL more than doubled the odds of significant coronary artery narrowing. Joining the study group in more recent years (after 2005) lowered the risk of significant coronary artery narrowing.
Figure 1. Low vitamin D levels and other factors shown here independently raised the odds of significant coronary artery narrowing in a study of 674 HIV-positive African Americans. Joining the study group after 2005 lowered the odds of significant coronary artery narrowing (not shown in graph). BP, diastolic blood pressure; LDL, low-density lipoprotein cholesterol; ART, antiretroviral therapy.
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