New cost-effectiveness estimates, combined with the most comprehensive evaluation to date of available prevention research, leave no doubt that the nation's efforts to prevent HIV infection have paid off. The Centers for Disease Control and Prevention believes the findings, presented at the 12th World AIDS Conference, will help HIV prevention programs make the best use of limited resources by basing program decisions on the science of what works best for populations at risk.
We have more evidence than ever before that prevention works and that it saves dollars in addition to lives," said Helene Gayle, M.D., M.P.H., Director of CDC's National Center for HIV, STD, and TB Prevention.
CDC scientists have developed important tools for estimating the economic impact of HIV prevention programs in the era of advanced combination therapies. The economic model estimates lifetime treatment costs (based on new treatment scenarios), and balances those costs against the current national investment in HIV prevention to determine what level of success is needed to save the nation money.
The findings indicate that only 3,995 infections must be prevented annually to actually result in cost-savings, and only 1,255 infections must be prevented for the investment to be cost-effective.
We found that even if only a relatively small number of infections are prevented each year, HIV prevention programs save money," said David Holtgrave, Ph.D., Director of NCHSTP's Division of HIV/AIDS Prevention B Intervention Research and Support. "Given what we know about prevention effectiveness, we believe that the number of infections actually prevented greatly exceeds the cost-saving level."
Holtgrave and colleagues estimate that the present cost of lifetime treatment for HIV now averages $154,402. This amount represents the money saved per infection averted through prevention. By dividing the national prevention budget of $616.79 million by the resources saved per infection prevented, he is able to determine the minimum number of infections that would have to be prevented to save money.
To determine the number of infections that would have to be averted in order to conclude cost-effectiveness, researchers add to the medical costs an estimate of what society is willing to pay per year of life saved. This estimate is derived from analysis of investment in other life-saving interventions, such as kidney dialysis and mammography. Researchers believe that the greatest benefit of these models will be to program planners attempting to make tough decisions about which prevention programs can make the biggest impact.
Combining this tool with research on which interventions work most effectively to prevent infection will allow those who allocate resources to ensure they are used most appropriately," stressed Holtgrave.
Other CDC presentations at the conference present the most comprehensive evidence to date that HIV prevention programs are effective. CDC researchers have assimilated and analyzed all available studies to date that evaluate the impact of prevention programs and created a database called Prevention Research Synthesis (PRS). The PRS database incorporates all well-conducted evaluations of the full range of HIV prevention programs, from school-based education to street outreach for injection drug users.
By conducting a meta-analysis on these studies, researchers can determine their overall impact. CDC researcher Ellen Sogolow, Ph.D., presented the overall findings, based on 46 U.S. studies of more than 18,000 individuals, indicating that participants significantly reduced their risk behaviors following the program interventions.
"The picture that results is clear. Well designed HIV prevention programs have had a positive impact." said Sogolow, "And they have made a difference for a wide range of populations at risk."
CDC behavioral scientist, Salaam Semaan, Dr.P.H., will present a subset of the overall analysis that looks at the impact of programs designed to reduce sexual risk behaviors among injection drug users, one of the most difficult to reach populations. Because of the dangerous intersection of drug-related and sexual risk behaviors, programs for injection drug users must strive to reduce not only drug-related risks, but also sexual risks.
Semaan and colleagues analyzed the combined impact of twenty-nine studies on the risk behaviors of over 11,000 injection drug users and found an overall positive effect. The vast majority of the interventions were effective in reducing sexual risk behaviors among injection drug users and none of the interventions were harmful.
"Our findings suggest that effective behavior change programs can slow the sexual spread of HIV among injection drug users and their partners," said Semaan. "Our challenge will be to help communities design programs that combine these approaches with the most effective interventions for reducing drug-related risks."
An analysis of the effectiveness of programs to reduce drug-related risk behaviors is underway and expected to be complete in the coming months. Sogolow will discuss several new CDC systems for putting the best prevention research into the hands of communities affected, including the PRS database. Sogolow will also present CDC prevention modules which help communities reproduce effective HIV prevention programs. Several prevention modules will be discussed, including a video-based discussion group intervention for minority women at high risk and an outreach program to influence peer opinion leaders that reach young gay men.
"CDC's role is to provide communities the best science available to guide prevention efforts," said Sogolow. "Pulling the best prevention research together into a tool that can be used to analyze, evaluate, and replicate scientifically sound programs is the first step toward extending their reach."