26 January 2015
To prevent heart attacks, researchers encourage quitting tobacco
In Canada and other high-income countries, the widespread availability of potent combination anti-HIV therapy (commonly called ART or HAART) has greatly reduced the risk of death from AIDS-related infections. ART is so powerful that doctors increasingly expect that some HIV-positive young adults who are recently infected and who begin treatment shortly after diagnosis and are able to take ART every day as directed and who do not have untreated or undiagnosed pre-existing issues (such as addiction and/or mental health issues) will likely live into their eighth decade.
As a result of the beneficial effects of ART and longer lifespan, doctors caring for HIV-positive people in Canada, Australia, New Zealand, Western Europe and the U.S. are increasingly focused on preventing and treating health issues commonly associated with aging.
One such issue is cardiovascular disease, particularly heart attacks. Over the past 15 years, observational studies have reported that HIV-positive people have an elevated risk for heart attacks. Researchers have proposed the following possibilities for the link between HIV infection and cardiovascular disease:
- HIV infection causes changes to cholesterol and other lipids in the blood.
- HIV triggers inflammation that increases the risk for a heart attack.
Both of these changes brought about by HIV may accelerate the process of underlying cardiovascular disease.
Other potential reasons for the increased risk of cardiovascular disease in HIV-positive people have been proposed, as follows:
- some anti-HIV drugs
- uncontrolled or poorly managed blood pressure and other related conditions
- co-infection with members of the herpes virus family such as CMV (cytomegalovirus)
Taking these and other points into account, infectious disease specialist Line Rasmussen MD, PhD (Odense University Hospital, Denmark), and colleagues have stated “the mechanisms that drive the association between HIV and the risk of [heart attack] seem to rely on complex associations of known and unknown factors.”
Confounding and confusion
Leading HIV researchers John Gill, MD (director of the Southern Alberta HIV Clinic, Calgary, Alberta), and Dominique Costagliola, PhD (Sorbonne Universités, Paris), note that observational studies of cardiovascular risk often have not taken into account the “very high use of tobacco smoking in the HIV population.”
Many studies among HIV-negative people have found that smoking tobacco greatly increases the risk for heart attack. By not collecting sufficient data about the use of this substance among HIV-positive people, observational studies may have inadvertently arrived at flawed conclusions about the cause of cardiovascular risk in this population.
Now two observational studies attempt to cast light on the risk of heart attacks among HIV-positive people today.
Dr. Rasmussen and colleagues compared data collected from about 3,000 HIV-positive people and 13,000 HIV-negative people. Their analysis found that HIV-positive people who never smoked tobacco had no increased risk for a heart attack. However, current smokers had a very large risk—about three-fold greater than HIV-negative people—for a heart attack. The Danish researchers estimated that if HIV-positive people in their study who smoked tobacco quit, 42% of heart attacks could be avoided.
In the U.S.
An American database operated by the health maintenance organization Kaiser Permanente in California first reported a large increased risk for heart attacks among HIV-positive people nearly 15 years ago. In their most recent analysis, the Kaiser researchers compared data from 25,000 HIV-positive people and 258,000 HIV-negative people. They found that particularly since 2010, HIV-positive people in the Kaiser database were no longer at elevated risk for a heart attack, in part because of declining rates of smoking and likely better control of blood pressure and cholesterol levels through medication.
If the life-extending benefits of ART are to be fully realized, more must be done to bolster the health of HIV-positive people in the 21st century. After reviewing the Danish results, researchers Gill and Costagliola encourage the movement to better health by urging doctors, nurses and pharmacists to do the following:
“Seizing every opportunity during HIV care delivery to focus our efforts to reduce the high rate of tobacco smoking offers the greatest potential for reducing [rates of heart attacks].” Furthermore, they added: “Encouragement and support for our patients in their efforts to stop smoking offers immense health benefits.”
Upcoming CATIE News stories will explore the Danish and American studies.
—Sean R. Hosein
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