The researchers found that from the beginning of the epidemic until 1985 (when new infections peaked), incidence of HIV predicted investment levels. During this period, society responded to increasing levels of infection with more investment in prevention programs. Things changed in the mid 1980s when investment levels began to predict incidence. That is, as the nation continued to increase the funding of HIV prevention programs, HIV dropped substantially from 160,000 infections per year to about 40,000 infections per year. In the early 1990s, as the level of investment (adjusted for inflation) flattened out with little annual change, so too did the number of new infections per year. This suggested to the researchers that level investment yields level incidence.
"Our analysis helps explain why the number of new HIV infections has remained at 40,000 per year for over 15 years," said David R. Holtgrave, PhD, chair of the Department of Health Behavior and Society at the Bloomberg School of Public Health and lead author of the study. "Investment levels have predicted HIV incidence since the mid-1980s. If we want to lower infections further in the U.S., these analyses suggest we should consider increasing our national investment. Yes, that may seem expensive, but HIV medical care easily tops $20,000 per patient per year. Therefore, funding of effective, scientifically sound HIV prevention services are likely to have a very favorable return on investment in terms of both lives and dollars saved."
Holtgrave noted that the analysis was based on historical data and is not a prospective trial of p revention effectiveness. Therefore, it is subject to methodological limitations. Nevertheless, he said it provides substantial indications of a strong relationship between the amount of national investment in HIV prevention and levels of new infections per year in the country.