Universal voluntary HIV screens prolong life without substantial cost increase
BY MICHELLE L. BRANDT
Expanding HIV screening would be a relatively cost-effective way to increase life expectancy and decrease disease transmission. That is the conclusion of researchers at the Veterans Affairs Palo Alto Health Care System and the School of Medicine who conducted a cost-effectiveness analysis of doing routine HIV screening.
"We're convinced based on what we've done that there needs to be more screening," said Douglas K. Owens, MD, MS, an investigator at the VA Palo Alto and associate professor of medicine at the School of Medicine's Center for Primary Care and Outcomes Research and the Center for Health Policy in the Stanford Institute for International Studies.
Owens' paper was published in Thursday's issue of the New England Journal of Medicine and appears alongside another cost-effectiveness study with similar findings. "The dovetailing of these two studies is breathtaking," said A. David Paltiel, PhD, associate professor of health policy and administration at Yale and lead author of the second study. "One rarely achieves such strong, external validation of model-based results, and it really seals the deal with regard to establishing the value of expanded HIV counseling, testing and referral in the United States."
While the findings have new urgency with the reports last week of a new strain of the HIV virus that is resistant to retroviral drugs, experts have long known the importance of the timely identification of HIV. Delays in a patient's treatment can lead to irreversible immunologic damage and complications, as well as transmission of HIV through risky behavior. The Centers for Disease Control and Prevention estimates that up to 20,000 new infections annually can be attributed to people who are unaware of their HIV-positive status.
A 2003 CDC initiative recommended making voluntary testing a routine part of medical care, yet Owens said screening is still not widespread. (Money is an issue, he said, as well as disagreement among experts over whether blanket or targeted screening is more effective.) The majority of HIV patients are diagnosed only after exhibiting symptoms that prompt testing: the CDC reports that more than 40 percent of patients don't learn of their infection until very late in the game.
"We know from other studies that people find out late in the course of the HIV infection—when they're almost to AIDS or already have AIDS," said Owens. "The current approach [to screening] is clearly inadequate."
Owens, along with first author Gillian Sanders, PhD, and their team at the VA, Stanford and St. Michael's Hospital in Toronto, developed a decision model to estimate the health benefits and expenditures of performing voluntary HIV screening programs in health-care settings. They followed a group of patients over their lifetime and looked at the costs and health consequences of screening and counseling, HIV transmission and current treatment guidelines and testing. They used historical data to determine rates of progression for HIV-positive patients not undergoing therapy, and they assumed a 20 percent reduction in risk behaviors for patients whose infection was identified.
The team used its model to determine the benefits of screening due to reduced transmission of HIV and early identification of HIV. The researchers found a 21 percent reduction in annual transmission with the use of a screening strategy, as compared with the absence of screening.
They also found that earlier identification through screening would lengthen life by 1.5 years for a person with HIV infection. In a population in which 1 in 100 persons has unidentified HIV infection (which is consistent with the CDC's recommended prevalence for screening), their model showed that one-time screenings throughout the United States would cost $15,100 per quality-adjusted life year (a common statistical measurement that takes into account quality of life as well as length of survival). And according to their calculations, routine screenings every five years cost $57,100 per quality-adjusted life year gained.
By comparison, routine screenings for hypertension, colon cancer and Type-2 diabetes range in cost from $48,000 to $56,000 per quality-adjusted life year.
"Our analysis indicates that screening for HIV infection is cost-effective relative to other commonly accepted screening programs and medical treatments," Sanders noted. "This finding suggests that in many health-care settings, HIV screening will provide important health benefits for a reasonable investment in health-care resources."
In the second New England Journal of Medicine study, researchers at Yale and Harvard developed a computer model of HIV screening and treatment to compare routine voluntary screening with current practice. They found that in all but the lowest-risk populations, routine and voluntary screening for HIV once every three to five years is "justified on both clinical and cost-effective grounds." The researchers concluded that "efforts to promote, finance and expand existing national HIV-testing guidelines should be pursued aggressively."
"It's exciting that a completely independent analysis had the same findings as we did," said Owens. "Both of these studies show that screening prolongs life and is affordable." Added Yale's Paltiel, "The publication of these papers represents a golden opportunity to jump-start the expansion of HIV testing services in the United States."
Now that researchers have determined that routine screening should be done, the next question to be answered is how. Owens said he's planning an analysis of different methods of screening-including newly approved, rapid testing protocols.