Anti-HIV treatment, weight and low income risk factors for heart disease

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People infected with HIV need to be better targeted for heart disease screening and treatment say the authors of one of the largest studies of HIV and cardiac health yet conducted. The study is published in the October 15th edition of Clinical Infectious Diseases.

Long-term antiretroviral therapy, particularly if it includes a protease inhibitor, is known to increase the risk of coronary disease (CHD), by around 40% over six years of follow-up, according to the results of the DAD study, chiefly due to the lipid elevations associated with protease inhibitor treatment.

In general, the incidence of CHD in the HIV-infected population has been low because patients have tended to be young.

Glossary

coronary heart disease (CHD)

Occurs when the walls of the coronary arteries become narrowed by a gradual fatty build-up. It may lead to angina or heart attack.

body mass index (BMI)

Body mass index, or BMI, is a measure of body size. It combines a person's weight with their height. The BMI gives an idea of whether a person has the correct weight for their height. Below 18.5 is considered underweight; between 18.5 and 25 is normal; between 25 and 30 is overweight; and over 30 is obese. Many BMI calculators can be found on the internet.

protease inhibitor (PI)

Family of antiretrovirals which target the protease enzyme. Includes amprenavir, indinavir, lopinavir, ritonavir, saquinavir, nelfinavir, and atazanavir.

naive

In HIV, an individual who is ‘treatment naive’ has never taken anti-HIV treatment before.

treatment-naive

A person who has never taken treatment for a condition.

But the ageing of the HIV population – a consequence of more effective therapies – means that heart disease and stroke are now becoming leading causes of death in people with HIV infection, as they are in the general population.

US researchers have now calculated the risk of developing CHD in HIV-infected men and women using two large cohorts of HIV-infected and non-infected people, the Women’s Interagency HIV Study and the Multicenter AIDS Cohort Study.

Together the studies involved 2386 HIV infected people (39% men and 61% women) and 1675 non-infected controls (66% men and 34% women).

The aim was to identify the factors which put HIV-infected people at greater risk of developing CHD.

The researchers used a calculator called the Framingham Risk Score to calculated a ten-year CHD risk, that is the chances of having a myocardial infarction (heart attack) or coronary death in the next ten years.

Among HIV-infected men, they found 2% of them had a ‘moderate’ predicted risk of CHD that is a 15 to 25% risk of a heart attack or coronary death in the next ten years. But 17% of men had ‘high’ risk that is a ten-year CHD risk of 25% or over.

In HIV-infected women 2% had moderate predicted CHD risk and 12% had high predicted CHD risk.

Overall, HIV-infected people who were treatment-naïve were significantly less likely to have moderate or high predicted CHD risk than those who were taking antiretroviral therapy containing a protease inhibitor (OR 0.57; 95% CI 0.36-0.89) (Kaplan RC 2007).

Other factors associated with increased likelihood of having a moderate to high predicted CHD risk were obesity, as measured by body mass index (body mass index [BMI] of 18.5 – 24.9 vs. 25 – 30: OR, 1.41; 95% CI, 1.03 – 1.93), and low income (below $10,000 per annum vs. above $40,000 per annum: OR, 2.32; 95% CI, 1.51 – 3.56).

But they also found a high number of current smokers among the HIV-infected cohorts - 35% of men and 43% of women - which is also known to substantially increase the risk of developing CHD.

They conclude that the data show people on a PI-containing antiretroviral therapy are more likely to develop CHD than HIV-infected people who are either treatment-naive or on a regime that does not contain a PI.

But low household income was also strongly related to predicted coronary risk.

Finally, intervening on risk factors such as being overweight and smoking presents an opportunity to cut the risk of heart diseases as well as improving HIV disease progression.

An editorial accompanying the study in Clinical Infectious Diseases stresses the findings have important public health implications as they suggest screening HIV-infected people for heart disease and attempting to tackle the risk factors might be valuable (Friis-Møller 2007).

But there are concerns that the Framingham Risk Score might not be as accurate for this population as for the general population, although CHD risk prediction tools tailored for use in HIV-infected people are under development.

References

Kaplan RC et al. Ten-year predicted coronary heart disease risk in HIV-infected men and women. Clin Inf Dis 45: 1074-1081, 2007.

Friis-Møller N and Worm SW. Can the risk of cardiovascular disease in HIV-infected patients be estimated from conventional risk prediction tool? Clin Inf Dis 45: 1082-1084, 2007.