Friday, December 2, 2011

Stroke risk higher in HIV patients



The treatments for the AIDS-causing virus may put HIV positive patients at a higher risk for cardiovascular trouble.

While the overall hospitalization rate for stroke has declined in recent years, the numbers have jumped dramatically for patients infected with human immunodeficiency virus (HIV), suggesting they may be up to three times more likely to suffer a stroke than people uninfected by the virus that causes AIDS. Strokes can result in rapidly occurring, permanent loss of brain function due to severely reduced or interrupted blood supply to the brain.

There's no direct proof linking the medications to the higher stroke rate, but previous research has suggested that HIV drugs can boost cholesterol and triglyceride levels, both of which contribute to stroke risk.

For their study, American researchers examined a database of hospitalisations for stroke from 1997, when a new generation of AIDS drugs was in its early days of use, through 2006.

It was found that while overall hospitalisations for stroke fell by 7 percent, the number of stroke hospitalisations in HIV-infected people rose by 60 percent in 2006. The researchers adjusted their numbers to account for factors such as age and gender. The time period studied coincided with the emergence and widespread use of highly active antiretroviral therapy (HAART) for HIV patients. HAART has been notably successful in extending the lives of HIV/AIDS patients, but emerging data suggest that these drugs can be associated with metabolic complications linked to higher risk of stroke.

The researchers also looked at the two kinds of stroke - ischemic (when a blood vessel is blocked) and haemorrhagic (when a blood vessel bursts). There was no change in the percentage of hemorrhagic stroke patients who were HIV-positive, but the rate went up from 0.08 percent to .18 percent - more than doubling - among HIV patients who had ischemic strokes. The latter number suggests, but doesn't prove, that more HIV patients are suffering from blockages in their blood vessels.

Stroke risk is highly correlated with increasing age. Almost three-quarters of strokes occur after the age of 65. Indeed, after 55, the risk doubles for each successive decade. However, among HIV patients the average age for a stroke was in the 50s and previous studies have shown that drugs used in HAART affect lipid and glucose levels, which are metabolic biomarkers associated with ischemic stroke risk.

The researchers advise that patients on HAART will clearly need to remain on the drugs to extend their lives, but the challenge will be to clarify whether HAART therapy is an innocent bystander or a direct culprit in this process. Furthermore, it would be helpful to find out if rates of heart attacks, are rising among HIV patients since they share similar underlying biological mechanisms to ischemic strokes.
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