In a major advancement for the field of HIV treatment, a new study has identified a more accurate method of suggesting prognosis for HIV patients.
The new method, called the Veterans Aging Cohort Study index, takes into account factors such as hemoglobin level, platelet count and comorbidity. Previous models of predicting HIV-related outcomes depended only on levels of CD4, a glycoprotein found on the surface of immune system T-cells, and viral load, an estimate of the amount of virus present in the body. But as improved antiretroviral therapy has lengthened the life expectancy of HIV patients, these two factors are no longer sufficient in developing a patient’s prognosis, said Amy Justice, a professor at the Yale School of Medicine and chief of general internal medicine for the VA Connecticut Healthcare System.
Two papers on the accuracy of the VACS index, one using data from a North American cohort and the other using data from a European cohort, were published in the journals JAIDS and AIDS, respectively, on Feb. 1.
The VACS index weighs different variables based on their association with mortality, Justice said, adding that prior to this development “doctors didn’t have a good way of combining all the available information together” to make an accurate prediction of life expectancy. Once the index was formulated, Justice and her co-authors evaluated its accuracy by analyzing data from 40,000 HIV patients in North American and European cohorts of the VACS, she said.
The researchers found that the VACS index was more accurate than the restricted indices in predicting HIV-related mortality, Justice said.
“Now that people with HIV are living full lives, we need a way to intervene with complications earlier and we need to get doctors to pay attention to more than CD4s and viral loads,” said University of Toronto professor Sean Rourke, another co-author of the study.
But the implications of these findings go even further than giving individual patients more accurate prognoses.
The new HIV markers identified can be used in clinical trials to test the success of different treatments and to “prioritize medications in terms of their overall benefit and lack of harm,” Justice said, adding that the index may lead to the development of more effective HIV treatments. Her next goal is to continue analysis of similar patient records and, by next year, publish a paper on how risk of mortality changes over time as a patient’s levels of markers such as hemoglobin and platelet count are modified, she said.
Work on the new index began when Justice became interested in the idea of comorbidity and its relationship to HIV outcomes approximately 10 years ago. Justice said she noticed that half of the HIV patients with whom she dealt in the tests she was running were coinfected with hepatitis C, but her idea was initially met with skepticism.
“At the beginning, people thought, ‘Why would we want to look at comorbidity?’ because all they really wanted to do was manage CD4 and viral load,” Justice said. “But the national scene changed once doctors recognized that HIV patients are living longer now, and that there have to be other things going on that we should take into account in our management.”
She added that in many instances a patient’s CD4 and viral load might be at healthy levels, but comorbid factors like liver or kidney failure could still decrease life expectancy.
Rourke said his next goal is to continue studying the link between HIV and neurocognitive impairment, which is a comorbidity that has not yet found its way into scientific literature.
The VACS Index Risk Calculator became available as a website and smartphone app in January.