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Eliminating Smoking and Hypertension Could Cut MI Rate 20% to 40% in HIV Group - [lack of prevention by providers for HIV+]
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7th International Workshop on HIV and Aging, September 26-27, 2016, Washington, DC
Mark Mascolini
Eliminating smoking and hypertension could avert more than one third of type 1 myocardial infarctions (MIs) and about one quarter of type 2 MIs, according to a 29,000-person analysis of NA-ACCORD HIV cohorts [1]. Preventing HIV-related risk factors, including low CD4 count and high viral load, would also have an impact on MI prevention.
NA-ACCORD researchers who conducted this study explained that about half of MIs in people with HIV are classic type 1 MIs--atherosclerotic coronary events resulting from plaque rupture. The other half, type 2 MIs, result from unbalanced myocardial oxygen supply and demand, which can be caused by sepsis or substance abuse. The NA-ACCORD team conducted this analysis to estimate population-attributable fractions (PAFs) of risk factors for type 1 and type 2 MIs in people with HIV. PAFs indicate the proportions of MIs that could be avoided if people do not have these risk factors [2].
The analysis included HIV-positive adults from 7 North American HIV cohorts contributing to NA-ACCORD who had a validated MI diagnosis from the start of 2001 through the end of 2013. The NA-ACCORD group is similar to the HIV population across the United States.
Preventable HIV-related risk factors included CD4 count below 200, viral load above 400 copies, and a clinical AIDS diagnosis. Preventable comorbid risk factors for type 1 MI were smoking, total cholesterol above 240 mg/dL, hypertension, diabetes, stage 4 chronic kidney disease (CKD), and HCV infection. The investigators recorded two risk factors--smoking and HCV--at study entry. They updated the remaining risk factors over the course of follow-up. Cox proportional hazard models to estimate MI risk were adjusted for age, sex, race, and injection drug use.
The study population included more than 29,100 HIV-positive people at least 18 years old who had 347 type 1 MIs and 275 type 2 MIs during a median follow-up of 3.5 years in 2001-2013. At the baseline study visit, people who later had an MI were older and more likely to have smoked, and to have high total cholesterol, hypertension, diabetes, stage 4 CKD, a CD4 count below 200, a clinical AIDS diagnosis, and HCV infection. People who had a type 1 MI were less likely to be antiretroviral naive than those without a type 1 MI.
In adjusted analyses, factors independently associated with a higher type 1 MI risk were smoking (adjusted hazard ratio [aHR] 1.8), treated hypertension (aHR 3.9), diabetes (aHR 1.5), stage 4 CKD (aHR 1.9), and a CD4 count below 200 (aHR 1.9). All of those factors were also independently associated with a higher risk of a type 2 MI, as where viral load at or above 400 copies (aHR 1.9), a clinical AIDS diagnosis (aHR 1.6), and HCV positivity (aHR 1.9).
The PAF analysis indicated that eliminating smoking would avert 38% of type 1 MIs in the study population and 22% of type 2 MIs. Eliminating hypertension would avert 41% of type 1 MIs and 26% of type 2 MIs. Eliminating total cholesterol levels above 240 mg/dL would prevent 43% of type 1 MIs. Eliminating diabetes would prevent 8% of type 2 MIs, and eliminating stage 4 CKD would have the same impact on type 2 MIs.
Several viral risk factors had substantial PAFs for type 2 MIs. Eliminating detectable viral loads would avert 20% of type 2 MIs and 6% of type 1 MIs; eliminating a clinical AIDS diagnosis would avert 12% of type 2 MIs; eliminating sub-200 CD4 counts would avert 11% of type 2 MIs and 10% of type 1 MIs; and eliminating HCV infection would avert 19% of type 2 MIs and 8% of type 1 MIs.
The researchers believe their findings "underscore the need to implement preventive interventions targeting both traditional MI risk factors as well as HIV treatment optimization in order to reduce the excess MI burden among adults aging with HIV."
References
1. Althoff KN, Gange SJ, Gebo KE, et al. Eliminating smoking and hypertension and effectively treating HIV would avoid a substantial proportion of myocardial infarctions among adults aging with HIV. 7th International Workshop on HIV and Aging, September 26-27, 2016, Washington, DC. Abstract 7.
2. World Health Organization. Health statistics and information systems. Metrics: Population attributable fraction. "The contribution of a risk factor to a disease or a death is quantified using the population attributable fraction (PAF). PAF is the proportional reduction in population disease or mortality that would occur if exposure to a risk factor were reduced to an alternative ideal exposure scenario (eg. no tobacco use). Many diseases are caused by multiple risk factors, and individual risk factors may interact in their impact on overall risk of disease. As a result, PAFs for individual risk factors often overlap and add up to more than 100 percent."
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