People infected with the Aids virus may be three times more likely to suffer a stroke than people not infected, US researchers said.
While stroke rates in the United States fell 7.2% in 2006 compared to 1997, rates have spiked among people infected with the human immunodeficiency virus or HIV, rising 67% during that same period.
Most of the increase is in strokes caused by a blood clot in the brain, a type called ischaemic strokes, which is by far the most common.
"Generally speaking, strokes in patients with HIV are not common, so the rise is notable," said Dr Bruce Ovbiagele of the University of California, US, and the VA San Diego Healthcare System, whose study appears in the journal Neurology.
The team analysed hospital discharge information on patients from a nationally representative sample of millions of patients from 1997 to 2006.
The study does not show why stroke rates are rising, but researchers say the study period coincides with widespread use of drugs used to treat HIV infection.
As strokes occur more frequently with advancing age, it could be that HIV patients who are taking the drugs are living longer.
HIV+ have strokes at younger age
But stroke patients with HIV in the study tended to be in their 50s, younger than the average age of around 65 for stroke patients.
So the strong HIV drug cocktails may be playing a role, too, Ovbiagele said.
Some studies have shown that HIV medications affect blood fats and blood sugar levels - two factors that are closely linked with strokes, Ovbiagele said.
He said people with HIV will need to take the drugs for the rest of their lives, but doctors should be aware of the potential stroke risk among these patients.
The team wants to study the relationship between HIV drugs and stroke more closely.
An estimated 33.3 million people worldwide have HIV, the virus that causes Aids, and more than 25 million have died from it. Without treatment, the virus destroys the immune system, leaving patients susceptible to infections and cancer.
More than 20 HIV drugs are now on the market and can be combined in various ways to control the virus.
Drugmakers include GlaxoSmithKline, Pfizer, Gilead, Bristol-Myers Squibb and Abbott Laboratories. - (Reuters Health, January 2011)