Risk of Strokes Is Increasing for People with HIV

The number of HIV positive people hospitalized due to ischemic strokes -- the type caused by blocked blood flow to the brain -- increased by 60% over the past decade, even as the number fell among the U.S. population at large, according to research described in the January 19, 2011, advance online issue of Neurology. Even after accounting for the larger number of people living with HIV, stroke risk increased by about 40% since 2001.

Numerous studies have found that HIV positive people are at higher risk of cardiovascular disease than their HIV negative counterparts, which may be attributable to persistent infection and resulting inflammation, antiretroviral therapy (ART), or some combination of these and other factors.

Caused by interruption of the brain's blood supply, strokes are classified as ischemic, due to blockage of blood flow (for example by a blood clot), or hemorrhagic, due to bleeding in the brain. The ischemic type can be an outcome of atherosclerosis, or buildup of cholesterol, cell debris, and other material in arteries.

Strokes are often included among the cardiovascular "events" recorded in such studies, but they have not been the focus of much separate research. However, they are an increasing concern as the HIV positive population ages.

In the present analysis, Bruce Ovbiagele from the University of California at San Diego and Avindra Nath from Johns Hopkins University looked at trends in the proportion and number of HIV positive individuals among stroke patients in the U.S.

The investigators collected data from all states that contributed to the Nationwide Inpatient Sample, and identified all patients admitted to hospitals between 1997 and 2006 with a primary diagnosis of stroke.

Results

• Looking at both ischemic and hemorrhagic strokes combined, HIV positive people made up 0.09% of all patients hospitalized with strokes in 1997, rising to 0.15% in 2006, a significant increase.
• Looking at only ischemic strokes, HIV positive people accounted for 0.08% of hospitalizations in 1997, rising to 0.18% in 2006, again a significant jump.
• The proportion of HIV positive people among patients with hemorrhagic strokes, however, did not change significantly during this period.
• In terms of actual numbers, 888 HIV positive people were hospitalized with strokes in 1997, rising to 1425 in 2006, a 60% increase that was largely attributable to more people living with HIV.
• During the same period, in contrast, the overall number of stroke hospitalizations among the general U.S. population fell from 998,739 to 926,997, a 7% decrease.
• The rate of strokes began to increase notably in 2001, increasing from 90 to 129 stroke hospitalizations per 100,000 HIV positive people between 2001 and 2006, a rise of about 43%.
• The median age of HIV positive people at the time of stroke hospitalization rose from 43 years in 1997 to 48 years in 2006.
• In a multivariate analysis, stroke patients receiving Medicaid, those in urban hospitals, and those with dementia, liver disease, kidney disease, or cancer were more likely to be HIV positive.

"Over the last decade in the United States, there has been a substantial and significant rise in patients hospitalized for stroke with coexisting HIV infection," the study authors concluded. "This has important public health and socioeconomic consequences."

"The median age for stroke in this [HIV positive] population was the fifth decade, which is much lower than that of the non-HIV-infected population," they elaborated in their discussion. "This indicates that HIV infection or its treatment is directly related to the stroke pathophysiology in this population."

HIV infection could potentially cause strokes via several mechanisms, they continued, including endothelial activation leading to accelerated atherosclerosis, opportunistic infections, cancer, and HIV-related heart disease, blood vessel dysfunction, and metabolic abnormalities. But it is unlikely that HIV is more apt to cause such problems now than it was in 1996.

A more plausible explanation, they concluded, is that the advent of effective combination ART in the mid-1990s allowed more people with HIV to reach an age at which the risk for strokes starts to increase.

Beyond that, "longer exposure to HIV, even at low viral load levels, may allow for the direct effects of the virus to increase stroke risk," they suggested. In addition, prolonged use of antiretroviral drugs may contribute to metabolic, blood vessel, liver, and kidney problems that can play a role in ischemic strokes.

Fortunately, strokes are "highly preventable," Ovbiagele told HealthDay, with lifestyle changes such as weight loss, controlling cholesterol, and quitting smoking.

Investigator affiliations: Stroke Center and Department of Neuroscience, University of California at San Diego, San Diego, CA; Division of Neuroimmunology and Neurological Infections, Department of Neurology, Johns Hopkins University, Baltimore, MD.

1/28/11

Reference
B Ovbiagele and A Nath. Increasing incidence of ischemic stroke in patients with HIV infection. Neurology (Abstract). January 19, 2011 (Epub ahead of print).

Other Source
R Dottinga. Stroke Risk May Be Higher in HIV Patients. HealthDay. January 19, 2011.