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."
Ovbiagele B et al. Increasing incidence of ischemic stroke in patients with HIV infection. Neurology, online edition, 2011.