Cardiovascular disease in people living with HIV in Africa under-studied, prevention neglected

The impact of cardiovascular disease in people living with HIV in sub-Saharan Africa is under-studied and more information is needed on how to manage its risks, researchers report in the journal Progress in Cardiovascular Diseases.

The research team, drawn from universities in Africa and the United States, highlight risk factors that may be especially important in sub-Saharan Africa, what is known about cardiovascular disease in people living with HIV in sub-Saharan Africa, and prevention priorities for the region.

Hypertension

Hypertension is the most important risk factor for cardiovascular disease in sub-Saharan Africa, the review authors say. A recent meta-analysis estimated that the global prevalence of hypertension in people living with HIV is 35% and the proportion of people living with HIV affected in sub-Saharan Africa will rise as the population ages. Monitoring blood pressure is likely to give the first warning of the development of metabolic syndrome, but African clinics often lack basic equipment for measuring blood pressure. Supplies of blood pressure-lowering drugs are unreliable, and management of hypertension is not integrated into HIV care, they warn.

Type 2 diabetes

People living with HIV on antiretroviral therapy (ART) are at four times higher risk of developing type 2 diabetes (diabetes mellitus) compared to people without HIV, cross-sectional studies suggest. Obesity and age influence the risk of developing type 2 diabetes and may explain the higher risk for the condition in people living with HIV. Increases in obesity in people living with HIV and ageing of the population are each likely to contribute to increased prevalence.

Obesity

Obesity is a major contributor to the development of type 2 diabetes and heart disease. Obesity is especially common among people living with HIV in South Africa, where almost one in four are obese. Weight gain after starting ART is contributing to the high burden of obesity in people living with HIV, especially in women. The impact of weight gain on cardiovascular risk in people living with HIV is uncertain and more data are needed to define weight thresholds that should trigger intervention.

Elevated lipid levels

Elevated LDL cholesterol is more common in people living with HIV on ART than their HIV-negative counterparts in sub-Saharan Africa. However, analysis of the impact of abnormal lipids on the risk of stroke in people living with HIV on ART found it played a much smaller role than other risk factors such hypertension.

Smoking

Smoking is the most important behavioural risk factor for cardiovascular disease worldwide and smoking rates are higher in people living with HIV in sub-Saharan Africa than in the rest of the population. Research is needed to identify the most successful smoking cessation interventions for people living with HIV in sub-Saharan Africa, say the researchers.

Sex

Whereas HIV-negative men generally have a higher risk of cardiovascular disease than women, the risk of cardiovascular disease is equivalent for men and women living with HIV in North America. Data on cardiovascular disease risk by sex in sub-Saharan Africa are lacking and the impact of risk factors such as obesity and pregnancy-related hypertension are unclear.

Air pollution

Globally, air pollution contributes to one in four deaths from cardiovascular disease. Air pollution is especially severe in sub-Saharan Africa but the extent to which it increases cardiovascular disease risk is uncertain. Smoke from household stoves has been shown to affect blood pressure and cardiac function but data on air pollution effects in people with HIV are lacking.

What is known about cardiovascular disease in people living with HIV in sub-Saharan Africa?

Some studies have looked at sub-clinical atherosclerosis, which predicts the future risk of cardiovascular events such as heart attack. Whereas studies in North America and Europe have tended to find a consistent pattern of greater sub-clinical atherosclerosis in people living with HIV, studies in sub-Saharan Africa have shown few differences between people living with HIV and age-matched HIV-negative controls in sub-clinical markers of cardiovascular risk.

Data on cardiovascular events in people living with HIV in sub-Saharan Africa are still lacking. A case control study in Malawi showed that people living with HIV had three times the risk of stroke compared to HIV-negative counterparts, but no prospective data on cardiovascular events are available.

The lack of epidemiological data makes it difficult to adjust risk scoring systems to sub-Saharan African populations and more data are needed to produce robust risk prediction models, the authors of the review say.

Several large prospective studies are already underway to measure cardiovascular risk factors including subclinical disease and assess long-term outcomes. The REPRIEVE study of statin treatment for primary prevention of cardiovascular disease in people living with HIV includes six sites in southern Africa and may supply region-specific data on the effectiveness and feasibility of statin treatment as a primary prevention measure.

What cardiovascular prevention interventions are most likely to reduce morbidity and mortality in sub-Saharan Africa?

The study authors identify three priority interventions for reduction of cardiovascular disease mortality and morbidity in sub-Saharan Africa:

• Early ART initiation: cardiovascular disease risk is higher in people with lower CD4 cell count nadirs, so early ART initiation, as recommended by the World Health Organization, has the potential to reduce cardiovascular risk. Low nadir CD4 counts because of late HIV diagnosis are still common in sub-Saharan Africa. Reducing late diagnosis of HIV is a priority for cardiovascular disease prevention.
• Integration of cardiovascular risk screening into HIV care, such as screening for hypertension. The public health approach to ART delivery, with standardised algorithms for management, should allow integration of screening and monitoring into routine care.
• Education of healthcare workers and people living with HIV about cardiovascular risk factors, screening and management.