(RxWiki News) By 2015, HIV patients are expected to be surviving to and past 50 years old. Therefore, these patients may need to be closely monitored for conditions tied to older age, such as heart disease.
A recent study found that HIV-positive patients were at increased risk for heart attack compared to people without HIV.
The researchers discovered that a low white blood cell count was the biggest predictor of heart attack risk in HIV-positive patients.
"See a doctor regularly if you are HIV-positive."
The lead author of this study was Michael J. Silverberg, PhD, MPH, from the Division of Research at Kaiser Permanente Northern California in Oakland, California.
The study included 22,081 HIV-positive patients who were members of a Kaiser Permanente California health plan between January 1, 1996 and December 31, 2009.
All participants were 18 years old or older, and considered to be in "in care" for HIV (they had at least one blood test during the study period).
This study also included 230,069 HIV-negative patients who were matched to the HIV-positive patients by year of care, age, sex and medical center. A total of 91 percent of the participants in each group were men.
The heart attack rate was 283 cases per 100,000 person-years in the HIV-positive group, versus 165 cases per 100,000 person-years in the HIV-negative group.
The researchers determined that the HIV-positive participants had a 44 percent increased risk of heart attack compared to the HIV-negative participants.
The increased risk was found to be independent of traditional heart disease risk factors, such as high blood pressure, older age, smoking, male sex and an abnormal amount of fats in the blood.
The only HIV-specific factor that was significantly associated with increased risk of heart attack in HIV-positive participants was nadir CD4 count.
CD4 cells are white blood cells that the HIV virus attaches to. Nadir CD4 count is the lowest CD4 count recorded after a person becomes infected with HIV.
A low CD4 count is considered to be 500 or fewer cells per microliter of blood, and indicates immunodeficiency (when the immune system has very little or no ability to fight disease).
Dr. Silverberg and colleagues found that the HIV-positive participants with recent CD4 count of fewer than 200 cells per microliter of blood had a 76 percent increased risk of heart attack compared to HIV-negative participants.
Nadir CD4 count of fewer than 200 cells per microliter of blood was associated with a 74 percent increased risk of heart attack in HIV-positive participants compared to HIV-negative participants.
The findings revealed that every increase of 100 cells in nadir CD4 count was associated with a 12 percent reduced risk of heart attack in HIV-positive participants.
HIV-positive patients who had a recent CD4 count or nadir CD4 count of 500 or more cells per microliter of blood did not have a significantly different risk of heart attack compared to HIV-negative participants.
The researchers concluded that immunodeficiency was the most important risk factor for heart attack among HIV-positive patients, and suggested that these findings strengthen the argument for administering HIV medication early on after being infected.
The authors mentioned a few limitations of their study. First, heart disease risk factors were recorded in routine doctor appointments. Second, information on the participants' family history of heart attack was unavailable. Third, the majority of the participants were men from California, so the findings may not be applicable to female HIV-positive patients or patients outside of California.
This study was published in the February edition of the Journal of Acquired Immune Deficiency Syndromes.
The Garfield Memorial Research Fund and Pfizer Pharmaceuticals provided funding.