The proportion of US patients hospitalised because of stroke
who are HIV-positive has increased significantly in recent years, investigators
report in Neurology. This was at a
time when stroke hospitalisations in the general US population were falling.
“There was a significant rise of approximately 67% in the
proportion of patients hospitalized for stroke who had prevalent HIV
infection,” write the investigators, who attribute this increase to “evolving
circumstances unique to HIV-infected patients” such as the inflammatory effects
of long-term infection with the virus.
Investigators undertook the study because there is little
information on stroke prevalence for patients with HIV and its risk factors.
They believed that such a study was especially timely as many patients with HIV
are now surviving into middle and older age, and because research suggests that
both HIV itself and possibly its treatment can increase the risk of
cardiovascular diseases.
Individuals hospitalised for stroke between 1997 and 2006
were included in the study. Data were collected from across the US from
hospitals that contributed information to the National Inpatient Sample.
Both HIV-positive and HIV-negative patients were categorised
according to the type of stroke causing hospitalisation: ischemic, caused by a
blocked artery, or haemorrhagic, caused by bleeding into the brain.
In 1997, 0.09% of all patients hospitalised because of
stroke were HIV-positive and this increased significantly to 0.15% in 2006 (p
< 0.001).
At the same time, there was a 7% fall in stroke
hospitalisations among the general US population (100,000 per year to 97,000
per year).
Actual numbers of stroke hospitalisations involving patients
with HIV increased 43% from 888 in 1997 to 1425 in 2006.
Furthermore, after 2001 the rate of hospitalisations for
HIV-positive patients increased by approximately 43% from 90 per 100,000 in
2001 to 129 hospitalisations per 100,000 in 2006. This increase was significant
(p = 0.02).
The proportion of patients hospitalised because of ischaemic
stroke more than doubled during the study (0.08% in 1997; 0.18% in 2006, trend
p < 0.001). However, the proportion of strokes caused by haemorrhage
remained stable. The investigators describe these findings as “noteworthy.”
Median age among the HIV-positive patients experienced
stroke was 43 years in 1997 and 48 years in 2006.
Factors independently associated with increased risk of
stroke for HIV-positive individuals included well-established demographic risk
factors including male sex, older age and black race (all p < 0.0001).
Other health problems also increased the risk of stroke,
such as a history of heart attack (p = 0.03), peripheral vascular disease (p
< 0.0001), dementia (p < 0.0001), liver disease (p < 0.0001), diabetes
(p < 0.0001), kidney disease (p < 0.0001) and cancer (p < 0.0001).
“Although the absolute numbers of stroke hospitalizations
with HIV infection are relatively small…this steep rise over a short period of
time may be of public health concern,” write the investigators.
Although their study was unable to show why there had been
this increase the investigators speculate, “HIV infection or its treatment is
directly related to the stroke pathophysiology in this population.”
"The average age for a stroke
among people with HIV was in the 50s, which is much lower than that of those
without HIV. This finding suggests that HIV or HIV treatments may be directly
related to stroke occurrence," said Dr Bruce Ovbiagele of University of California at San Diego, who carried out the study with Dr Avindra Nath of Johns Hopkins University, Baltimore.
"Indeed, one potential
explanation is the increasingly widespread use of combination antiretroviral
medications in HIV-infected people. While these therapies have greatly
increased life expectancy, they may boost the presence of risk factors associated
with stroke. Another possibility is that longer exposure to HIV as a result of
greater survival, even at low viral load levels, may allow for the virus to
increase stroke risk."