Many study groups have attempted to define the cardiac risks faced by HIV-infected patients, with an emphasis on traditional risk factors and antiretroviral exposures. In this large prospective study, investigators focused on the risk associated with the infection itself.

Using the HIV Outpatient Study (HOPS) database, the researchers identified 2005 HIV-infected patients for whom a baseline cardiac risk profile could be calculated according to the usual Framingham criteria. These individuals represented only about half the patients who were otherwise eligible.

During a median 5.5 years of follow-up, 148 patients (7%) experienced a clinical event indicative of atherosclerotic coronary disease (including cardiac events, ischemic stroke, and peripheral arterial disease). The frequency of clinical events was correlated with the Framingham risk score: Events were roughly eight times more common in high-risk patients than in low-risk ones. Baseline CD4-cell count was also independently associated with likelihood of a clinical event: The attributable risk associated with a CD4 count <500 cells/mm³ was 25.6%, around the same magnitude as the effects of cigarette smoking and hyperlipidemia, and larger than the effects of male sex and diabetes. A case-control analysis yielded similar results.

Some antiretrovirals were modestly associated with cardiac risk in univariate analyses, but the associations did not retain significance after adjustment for other factors. The study did not address what happened to cardiac risk in successfully treated patients.

Comment: Because this study did not include patients whose Framingham risk scores could not be calculated from the medical record — presumably because they were considered at low risk for cardiac events — its findings cannot be generalized to all patients. However, the study does suggest that in the subset of patients whose doctors are — for whatever reason — concerned enough about cardiac events to record all the pertinent baseline values, low CD4-cell counts worsen cardiac prognosis.

Published in Journal Watch HIV/AIDS Clinical Care July 19, 2010