SEATTLE – HIV infection is associated with increased risk of recurrent venous thromboembolism, especially within 1 year of the initial episode. The finding, presented during a poster session at the Conference on Retroviruses & Opportunistic Infections, follows up on an earlier study that found that first-time VTE risk also is higher among HIV-positive individuals than in the general population.
The conclusion about first-time VTE risk, published earlier this year in, came from a comparison between the (AIDS Therapy Evaluation in the Netherlands) cohort and European population-level of studies of VTE. It found a crude incidence of 2.33 VTE events per 1,000 person-years In HIV patients, with heightened odds when CD4 cell counts were below 200 cells/mcL (adjusted hazard ratio, 3.40).
The new work represents a follow-up and compared results from ATHENA (153 patients with HIV and first VTE) and the Dutch MEGA cohort (4,005 patients without HIV, with first VTE), which includes the general population. Overall, 26% of patients in the ATHENA cohort experienced a second VTE event, compared with 16% of the general population. At 1 year after anticoagulation withdrawal, HIV-positive individuals were at 67% increased risk (HR, 1.67). At 6-years after withdrawal, the relationship was not statistically significant (HR, 1.22).
Researchers also found that CD4 cell-count recovery was associated with lowered risk, with every 100 cell-count increase between initial VTE diagnosis and anticoagulant withdrawal linked to a 20% reduction in risk (HR, 0.80).
“The clinical question is: If it’s true you have an increased risk of recurrence, should you be continuing anticoagulant therapy longer in people with HIV? This poster doesn’t answer that question and you probably need a randomized, controlled trial to look at that,”, professor of medicine at Amsterdam University Medical Center, said in an interview during the conference.
In the absence of a clear answer, it’s sensible for clinicians to be aware of the potential increased risk, much as clinicians have internalized the increased risk of atherosclerotic vascular disease in HIV patients. “I think the publication [in Lancet HIV] as well as this poster suggest that on the venous side of things there may also be an accentuated risk,” said Dr. Reiss.
, a professor of medicine at the University of Washington, Seattle, presented a poster examining the underlying factors that may predispose HIV patients to first-time VTE events. Her team performed an adjudicated review of VTE cases among HIV patients at six institutions and found that the risk factors appeared to be distinct from those seen in the general population.
The traditional long plane ride was less common in this population, while factors such as injected drug use and pneumonia were more common. The VTE events occurred at a median age of 49 years; 30% of the patients had a detectable viral load. “We’re seeing a little more (VTE) than you might expect, and in a younger population than you might have guessed,” said Dr. Crane in an interview.
The most frequent predisposing risk factors were recent hospitalization (40%), infection (40%), or immobilization/bed rest (24%) within the past 90 days, and injectable drug use (22%). “It’s not just the traditional risk factors. Some HIV-specific risk factors are driving this,” said Dr. Crane.
She also aims to learn more about the specifics of risk factors, such as catheter-associated thromboses. The team is working to increase the sample size in order to parse out the relationships with specific outcomes.
In the meantime, the data further characterize the health challenges facing people living with HIV. “This is another example demonstrating that comorbid conditions among patients with HIV that are often considered age related occur at much younger ages in our population,” said Dr. Crane.