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Implications for practise and research
HIV seropositive status adds to the risk of coronary heart disease.
This will have an impact on the morbidity and mortality patterns of persons who are HIV-positive (HIV+) as they age.
The reasons as to why this excess risk exists and what rational interventions should be used to reduce the risk remain key areas of research.
The continued use of antiretroviral therapy (ART) allows persons who are HIV+ to survive to an age where the risk of cardiovascular disease (CVD) in the general population is prominent. Traditional risk factors drive the risk of CVD in persons who are HIV+ to an extent comparable with the general population. These risk factors (eg, smoking, diabetes and dyslipidaemia) are seen more frequently in HIV+ populations. Prior publications have established that persons who are HIV+ are at an elevated risk of coronary heart disease (CHD) compared with the general population; however, it has remained unclear whether the excess risk could be explained by the higher prevalence of risk factors or not.1 ,2
Data contained in various administrative databases were merged to build a study database that contained information on traditional risk factors (demographics, hypertension, dyslipidaemia, diabetes, renal disease, anaemia, body mass index, smoking and diabetes), medical interventions to reduce the risk of CVD (eg, statins and antihypertensives), HIV status and myocardial infarctions (MIs) that occurred during a defined period. These databases contained data on US veterans. The study database was used to compare the incidence of MI in persons who are HIV+ against HIV-negative (HIV−) after taking into account the presence of risk factors in these two populations. Only persons without a prior history of CVD were included.
The relative risk (RR) of MI was found to be 48% higher in the HIV+ population compared with the HIV−, after taking into account each population's underlying risk of this outcome, based on the presence of CVD risk factors (this underlying risk was determined by applying the Framingham Risk Score for each individual person). This excess risk was found irrespective of whether the persons who are HIV+ were or were not on ART. In addition to a HIV+ status, the risk of MI was also associated with age, hypertension, diabetes, dyslipidaemia, smoking, impairment of renal function and anaemia. A total of 82 459 persons participated in the study and were followed for around 6 years, during which time a total of 871 persons developed an MI.
This study provides evidence to support that an HIV+ status is associated with an increased risk of MI. This excess risk appears not to be explained by a higher prevalence of traditional risk factors for this outcome. Additionally, the 48% excess risk is in relative terms and hence will become gradually more impactful as the HIV+ population acquire traditional risk factors; if the 10-year risk of MI is, for example, 1%, then an added 48% RR will raise this 10-year risk to about 1.5%; conversely, if the 10-year Framingham Risk is 20%, then the 48% RR will increase this to approximately 30%. Since most persons who are HIV+ are still in their forties, we should expect to see CVD as a major cause of morbidity and mortality within the next decade.
Reliable prediction of the future risk of MI is important to guide behavioural and medical interventions aimed at reducing the risk in this population. As the risk increases, the necessity and aggressiveness of the interventions considered also increases. Specific prediction models to assess 5-year risk already exist, such as the DAD 5-Year Estimated Risk calculator that can be used for routine care.3 These models take into account relevant HIV-specific factors and appear to be better at predicting 5-year risk of MI in the HIV+ population than, for example, the Framingham equation, and predictive models otherwise used in the general population.
There are several potential biological mechanisms to explain the excess risk of MI in HIV+ populations. This is an area of active research, which may serve as promising targets for novel interventions. A few of the most prominently discussed at this time are the choice of antiretroviral agents composing effective ART, when to initiate this intervention in the course of chronic HIV infection and the possible use of specific anti-inflammatory and/or anticoagulative drugs. In the meantime, it remains critical to reduce smoking, prevent excess weight gain (as it predisposes to type II diabetes) and to diagnose and treat hypertension and dyslipidaemia as appropriate.
Competing interests None.
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