Smoking the biggest single risk factor for acute heart disease in people with HIV

Smoking is the single biggest risk factor for acute coronary syndrome in HIV-positive adults, Spanish researchers report in the online edition of HIV Medicine. Smoking was a much more important factor than diabetes and hypertension combined.

“Future efforts to decrease the burden of cardiovascular disease should focus on developing widespread and effective smoking cessation strategies in HIV-positive adults,” comment the authors.

Improvements in HIV treatment and care mean that many HIV-positive people can expect to live long and healthy lives. Nevertheless, the life expectancy of people with HIV is often still shorter than that of HIV-negative individuals. One reason for this is higher rates of cardiovascular disease seen in those with HIV.

The exact reasons for this increased risk of cardiovascular risk are controversial.

However, it is likely to be because of a high prevalence of traditional risk factors, such as smoking, diabetes and hypertension; the immune damage and inflammation caused by HIV; and the side-effects of some antiretroviral drugs.

Prevention and detection of cardiovascular disease are now a priority in routine HIV care. It is therefore important to understand the contribution of individual factors to the overall risk of cardiovascular disease.

Investigators in Spain designed a case-controlled study. The study involved people who received care between 1997 and 2009 in Barcelona.

A total of 57 HIV-positive people with acute coronary syndrome (an umbrella term for situations when blood supply to the heart is obstructed due to blocked arteries) were matched with HIV-positive people without this form of cardiovascular risk. They were also matched with HIV-negative patients who had similarly been diagnosed with acute coronary syndrome, and these HIV-negative patients were in turn matched with HIV-negative people who were not diagnosed with this disorder.

The study enabled the investigators to identify the risk factors for acute coronary syndrome in HIV-positive and HIV-negative people and to calculate the risks attributable to specific factors such as smoking, diabetes, hypertension, family history and elevated cholesterol.

Most (57%) of the participants were men and their mean age was 53 years.

Traditional risk factors were highly prevalent in both the HIV-positive and HIV-negative participants who were diagnosed with acute coronary syndrome.

However, the prevalence of smoking in those with HIV was almost twice that observed in the HIV-negative participants (72 vs 40%). These HIV-negative individuals were approximately twice as likely as HIV-positive people to have hypertension (46 vs 25%).

Restricting analysis to the participants with HIV showed that those with acute coronary syndrome were significantly more likely to smoke (72 vs 42%, p < 0.001), have a family history of cardiovascular disease (12 vs 3%, p < 0.02) and to have elevated cholesterol (39 vs 25%, p 0.04) than those without this form of cardiovascular disease. HIV-related parameters such as CD4 cell count, viral load and use of antiretroviral therapy were similar between HIV-infected participants diagnosed with acute coronary syndrome and HIV-positive people without this diagnosis.

The investigators calculated that smoking (OR = 4.1; 95% CI, 2.0-8.4, p < 0.001) and family history (OR = 7.6; 95% CI, 1.9-32.1, p = 0.003) were significant risk factors for acute coronary syndrome in the HIV-positive participants. Diabetes, hypertension and elevated cholesterol were not.

Risk factors for the HIV-negative participants also included smoking (OR = 4.3; 95% CI, 2.4-7.8, p < 0.001), but unlike HIV-positive people, diabetes (p = 0.002) and hypertension (p < 0.001) were also significant whereas family history was not.

Smoking accounted for 54% of the risk of acute coronary syndrome in the HIV-positive people, almost double the risk (31%) attributed to this risk factor among HIV-negative participants.

“Of all interventions targeting modifiable cardiovascular risk factors…stopping smoking is probably the intervention with the greatest impact,” write the authors. “The Data Collection on Adverse events of Anti-HIV Drugs (D:A:D) study found that the risk of myocardial infarction and cardiovascular disease decreased with each passing year of having stopped smoking, and the risk almost halved after 3 years.”

The investigators also stress the importance of intervening to address other factors, such as diabetes, cholesterol and diabetes, even though these made a relatively minor contribution to the overall risk of acute coronary syndrome in HIV-positive people. “HIV physicians should…pursue optimal management strategies of these conditions and targeted prevention and treatment strategies with hard cardiovascular endpoints.”

Sanchez-Calvo M et al. Differences between HIV-infected and uninfected adults in the contributions of smoking, diabetes and hypertension to acute coronary syndrome: two parallel case-control studies. HIV Med, online edition. DOI: 10.1111/j.1468-1293.2012.01057.x, 2012.