Decreasing undiagnosed HIV infection helped reduce rate of HIV transmission in US

Reducing the number of undiagnosed HIV infections in the US helped to prevent an estimated 6,000 new infections over a three year period and may have saved up to $5 billion in healthcare costs, according to an article published in the March 1^st edition of the Journal of Acquired Immune Deficiency Syndromes.

In the US and Europe decreasing the number of undiagnosed HIV infections is a priority. Earlier research has shown that individuals whose HIV is undiagnosed are more likely to engage in activities that involve a risk of HIV transmission than patients with diagnosed HIV. In addition, diagnosis of HIV provides individuals with the opportunity to access specialist care and antiretroviral therapy. Not only can antiretroviral therapy mean a longer and healthier life for patients with HIV, but by lowering HIV viral load, it can also significantly reduce the risk of HIV transmission.

According to estimates from the USA Centers for Disease Control, the proportion of patients with HIV whose infection was undiagnosed infection fell from 30% in 2001 to 25% in 2004. At the same time, the number of new, or incident, HIV infections remained stable at 40,000 per year.

There is disappointment that HIV prevention efforts have not reduced the number of incident HIV infections in recent years. However, such disappointment is tempered by an acknowledgement that at least the number of new infections did not increase against a background of growing HIV prevalence.

Investigators from the Medical College of Wisconsin and Johns Hopkins University in Baltimore developed a basic mathematical model of the US HIV epidemic between 2001 and 2004. Using this model they calculated the number of incident HIV infections that would have occurred between 2001 and 2004 had the proportion of undiagnosed infections remained unchanged. They then calculated the number of new HIV infections prevented between 2002 and 2004 because of the increase in the proportion of people with HIV whose infection was diagnosed.

The model showed that the number of cases of people living with HIV in the US increased from 950,000 in 2001 to 1,041,522 in 2004. During this period there were 160,000 (40,000 per year) new HIV infections, and 68,478 people with HIV died (a mortality rate of 2% per year).

Had the proportion of patients aware of their HIV infection not increased there would have been an additional 1000 HIV infections in 2002, 2000 additional infections in 2003, and 3000 in 2004.

“Our analyses suggest that the increase in serostatus awareness between 2001 and 2004 can be credited with preventing nearly 6000 incident HIV infections during the three-year period between 2001 and 2004”, write the investigators.

They continue, “one can argue that the incidence of HIV in the United States remains unacceptably high and that this indicates a failure of HIV prevention. The first assertion may be true.” But they are not persuaded by the second as it “fails to consider the counterfactual. The present analysis indicates that had serostatus awareness levels remained constant from 2001 to 2004, the incidence of HIV would have increased”.

The investigators conclude, “although additional prevention activities are needed to reduce HIV incidence to lower than current levels, the success of past prevention efforts should not be overlooked.”