HIV infection is associated with an
increased risk of stroke, US research published in the online edition of the Journal of Acquired Immune Deficiency
Syndromes shows. The association between HIV and stroke was significant
even after controlling for traditional risk factors. Viral load was the most
important HIV-specific risk factor.
“Stroke risk was increased in association
with increasing viral load, suggesting that poorer virologic control and its
inflammatory and immunologic sequelae may increase cerebrovascular risk,”
comment the authors.
It is now well recognised that HIV is
associated with an increased risk of cardiovascular disease. Despite this, the
effect of HIV on the risk of stroke is unclear.
Investigators in Boston therefore designed
a study to determine if HIV infection was associated with an increased risk of
stroke. They also wished to see if any HIV-specific factors were associated
with the disease.
They compared incidence of stroke between
4308 HIV-positive people seen between 2005 and 2007 to that observed in
32,000 matched HIV-negative people as controls.
There was a higher prevalence of
traditional stroke risk factors among the patients with HIV. These included
hypertension, diabetes, smoking, cardiomyopathy, left-sided valvular heart
disease and heart failure (all p < 0.001).
A total of 132 strokes were observed in the
HIV-positive patients, with 782 events recorded in the HIV-negative controls.
Incidence of stroke was 5.27 per 1000
patient-years for the people with HIV and 3.75 per 1000 patient-years
for the HIV-negative participants.
In the investigators’ unadjusted analysis,
HIV infection was associated with a 40% increase in the risk of stroke (HR =
1.40; 95% CI, 1.17-1.69, p < 0.001).
Taking into account traditional risk
factors attenuated this finding. Nevertheless, risk of stroke was still
significantly higher for the HIV-positive participants (HR = 1.21; 95% CI,
1.01-1.46, p = 0.046).
“Smoking and hypertension were risk factors
that were more highly prevalent among the HIV population and significantly
associated with stroke,” note the authors. “These risk factors might therefore
be particularly targeted for intervention in the HIV population.”
The association between HIV infection and
an increased risk of stroke was significant for women (HR = 2.16; 95% CI,
1.53-3.04, p < 0.001), but not for men (HR = 1.18; 95% CI, 0.95-1.47, p =
The increased risk of stroke for people
with HIV was restricted to younger people (18 to 49 years). For instance, HIV-positive
people aged between 18 and 29 had
a four-fold increase in their risk of stroke compared to HIV-negative people
of the same age (IRR = 4.42; 95% CI, 1.56-11.09).
“The effect of HIV on stroke may be more
pronounced in younger patients before traditional age-related vascular risk
factors begin to play a major role,” suggest the authors.
Analysis of HIV-specific factors showed
that higher viral load increased the risk of stroke (p = 0.001).
Longer duration of the use of
antiretroviral therapy reduced the risk of stroke (p < 0.001), as did a
viral load below 400 copies/ml (p = 0.008).
“We demonstrate the novel finding that
stroke risk is increased for HIV patients relative to control patients and that
this risk persists in part after accounting for traditional stroke risk
factors,” conclude the investigators. “The demonstrated association between HIV
and stroke should prompt medical providers to view HIV as a risk factor for
stroke and to have a low threshold to aggressively modify vascular risk,
particularly in women and the young – groups not typically identified as