HIV patients in the U.S. start treatment earlier than patients elsewhere in the world, according to an analysis of immune system markers presented here.
However, a patient in the U.S. still began treatment when his or her immune system was already below guidelines for starting therapy, according to Matthias Egger, MD, of the University of Berne in Berne, Switzerland.
And the U.S. falls back into the middle of the pack when it comes to improving over time the proportion of patients who start therapy at or above guidelines, Egger reported at the annual Conference on Retroviruses and Opportunistic Infections (CROI).
The finding comes from an analysis of more than 309,000 patients starting anti-retroviral therapy in 48 countries, looking at the number of CD4-positive T cells, a key marker of immune system health.
In the U.S. and most developed countries, guidelines state a patient should start therapy when his or her CD4-positive count is below 500 cells per cubic millimeter of blood. In developing nations, the bar is set lower - at 350 CD4-positive T cells in most cases.
Egger told reporters that, regardless of national income, most countries had increased the average CD4 count at which patients started therapy over the period from 2002 through 2009.
“Obviously, what we would like to see is the CD4 count going up quite dramatically,” Egger said, but the average is still below local recommendations everywhere. “The bottom line is there is still a long way to go.”
He told MedPage Today that the findings imply that around the world, many patients continue to start treatment “when they are quite sick and coming to the clinic with immunodeficiency.”
Since the beginning of the HIV and AIDS epidemic well over half a million people have died of AIDS in America – the equivalent of the entire population of Las Vegas. There are currently around 1.2 million people living with HIV in the United States of America and around a fifth of these are unaware of their infection, posing a high risk of onward transmission.
America’s response to the AIDS epidemic has produced mixed results. HIV prevention efforts have not always been successful and in 2009 approximately 54,000 Americans were infected with HIV, that is about one every nine-and-a-half minutes. Washington DC has an HIV prevalence of 3.2 percent among people over 12 years - similar to rates in some parts of sub-Saharan Africa.
Despite the seriousness of the epidemic, particularly in certain geographic areas and among certain demographic groups, America lacked a comprehensive plan on AIDS until 2010. President Obama had promised to rectify this during his election campaign by committing to the creation of a National HIV/AIDS Strategy. The Strategy, which was launched in July 2010, is structured around three core aims: reducing new HIV infections, increasing access to care and improving health outcomes for people living with HIV, and reducing HIV-related disparities and health inequities.
Stigma and discrimination towards HIV positive people still persist and thousands of uninsured Americans struggle to access good HIV care and antiretroviral therapy. The world’s biggest donor of AIDS-related funding is itself facing a major, ongoing AIDS epidemic.
In 2009, U.S. patients started treatment with an average CD4 count of 307, which was still below the 350-cell guideline of the time and well below the current guideline, Egger reported.
The 2009 average in the U.S. had risen from the 2002 number, but only by about eight cells a year. In contrast, Burkina Faso in Africa, one of the world’s poorest nations, led the pack by increasing the average by about 25 cells a year, although from a much lower starting point.
Estimating HIV Prevalence
Prevalence of HIV infection in the United States overall has been estimated with two different methods. The first method is to gather results from serosurveys in different populations and different geographic regions, put them together with estimates of the size of the populations at risk, and develop an overall estimate that synthesizes all the data. There are three main sources of error in this approach: 1) most of the serosurveys are not population-based and are difficult to generalize beyond the venue in which the HIV testing was done; 2) coverage of geographic regions and specific subpopulations at risk is not complete; and 3) the sizes of the populations at risk are not known with any precision-the numbers of homosexual men and of injecting drug users in the United States, for example, are particularly difficult to estimate.
The second approach to estimating prevalence uses a mathematical model called “back calculation,” which combines the available data on the numbers of reported AIDS cases and the incubation period distribution of AIDS (the mathematical function that estimates the probability of developing AIDS for each year following HIV infection) to derive how many HIV infections occurred during years past. With information on past infections and AIDS cases, current HIV prevalence can be estimated. This technique requires fairly complete surveillance of AIDS cases and an accurate estimate of the incubation period distribution. It is limited by its inability to estimate HIV infections in recent years with any precision. More significantly, the large, and as yet largely unmodeled, effect of antiretroviral therapy on the incubation period has rendered back-calculation currently ineffective in estimating prevalence. The complexity of treatment regimens and their effects appear unlikely to be captured by an adjustment to the incubation distribution. For this reason, back calculation may no longer be a useful method of estimating HIV prevalence.
Overall, Egger said, low-income countries ramped up the CD4 count average by about 100 to 150 cells per mm3 over the study period, starting from an average of about 75 in 2002.
Similar rises were seen in middle-income countries, from a slightly higher starting point.