PETRA: Module 1, Chapter 1

AIDS Prevalence, Incidence, and Mortality in the United States

As the yellow line in the above graph shows, the number of new AIDS cases (that is, AIDS incidence) has been decreasing since 1993. In 1993, approximately 80,000 adults and adolescents were diagnosed with AIDS. By 1999, that number had dropped by about 50%, to approximately 40,000 cases. Decreases in incidence were partly due to better HIV prevention, such as organizations testing their blood supplies for HIV, and individuals practicing safer sex.

In contrast, the orange line on the graph shows that the number of people living with AIDS (that is AIDS prevalence), is increasing. In 1993, approximately 75,000 adults and adolescents were living with AIDS in the United States. By 2001, U.S. AIDS prevalence had increased to 360,000 adults and adolescents--an almost 500% increase from 1993. This increase in the number of adults and adolescents living with HIV/AIDS in the United States is primarily due to the use of highly active antiretroviral therapy (HAART), which was introduced in 1996. This therapy slows the progression of AIDS, so that people with AIDS live longer with a better quality of life, increasing the number of people living with AIDS (2).

The blue line on the graph represents AIDS mortality--the number of people who died from AIDS in a given year. After rapidly increasing in the 1980s and early 1990s, the annual AIDS death rate peaked in 1995, decreased through 1997, and leveled after 1998. Like the increase in AIDS prevalence, the decrease in AIDS mortality was largely due to improvements in drug therapies. New and more effective medications for opportunistic infections (infections that take advantage of HIV+ people's weakened immune systems) may have also contributed to this decrease.

While new therapies for treating HIV/AIDS have been responsible for decreasing AIDS-related mortality, treating AIDS can be very complicated and difficult. People with HIV/AIDS often take many medications and the appropriate dosage of these medications must be taken on a specific time schedule. Unfortunately, the medicines, while effective, sometimes have unpleasant side effects which may discourage people form taking them as prescribed. Also important, if not taken properly, HIV may become resistant to the medicines, meaning that the medicines no longer work as well. Thus, rates of AIDS mortality may not continue to decrease until new and improved treatments are available.

U.S. Regional Disparities in AIDS Death Rates

While the U.S. as a whole saw AIDS mortality rates plummet between the years 1995 and 1998, the U.S. South saw its rates of death by AIDS increase. Overall, the annual number of deaths caused by HIV is highest in the South, and continues to increase over time. Between 1987 and 1999, the proportion of deaths due to HIV infection that were among residents of the South increased from 28% to 45%, while the proportion in the Northeast decreased from 39% to 29%, and the proportion in the West decreased from 24% to 15% (3).

Regional differences in percentages of U.S.
deaths due to AIDS from 1987-1999 (3).

Source: http://www.cdc.gov/hiv/graphics/images/l285/l285-21.htm

Understanding U.S. HIV/AIDS Surveillance Data

Surveillance is the ongoing, systematic collection, analysis, interpretation, and sharing of health data (3). These data not only show patterns of disease incidence, prevalence, and mortality, but also help predict how much a disease will affect a specific population.

One of the major collectors and distributors of data about the HIV/AIDS epidemic is the U.S. Centers for Disease Control and Prevention (CDC). The CDC collects two sets of data to track the HIV/AIDS epidemic in the United States. One results from HIV surveillance, and the other results from AIDS surveillance.

HIV Surveillance:

Since 1998, 29 states and the U.S. Virgin Islands have reported new HIV infections to the CDC, providing sufficient data to monitor HIV trends over time and to understand better the behaviors that increase the risk for HIV infection. These data are statistically adjusted for reporting delays. Since 1998, additional areas have begun reporting new HIV cases. Data from all these areas can be used to describe, more accurately, the recent epidemiology of HIV in the United States and its territories (4).

AIDS Surveillance:

AIDS diagnoses are reported to the CDC by all U.S. states and territories. Because of the lengthy interval between HIV infection and AIDS diagnosis, AIDS data cannot be used to show trends in new HIV infections. These data are statistically adjusted for reporting delays and are used to look at AIDS trends in the United States (4).

References:
1. Centers for Disease Control and Prevention (CDC). Incidence, prevalence, and deaths among persons with AIDS, 1985-2001,United States. Slide 17 of 17, CDC AIDS Surveillance- Trends slide series L207. Retrieved on February 18, 2004 from http://www.cdc.gov/hiv/graphics/images/L207/L207-17.htm.

2. Osmond, D.H. Epidemiology of HIV/AIDS in the United States. HIV InSite Knowledge Base Chapter. San Francisco, CA: Center for HIV Information, University of California, San Francisco, 1998. Retrieved on November 22, 2004 from http://hivinsite.ucsf.edu/InSite?page=kb-01-03#S1.4X.

3. Centers for Disease Control and Prevention (CDC). Trends in the Percentage Distribution of Deaths due to HIV infection by Geographic Region, USA, 1987-1999. Slide 21 of 36, Mortality slide series L285. Retrieved on February 18, 2004 from http://www.cdc.gov/hiv/graphics/images/l285/l285-21.htm.

4. Centers for Disease Control and Prevention (CDC). Fact Sheet: HIV/AIDS Among African Americans, 2003. Retrieved on February 24, 2004 from http://www.cdc.gov/hiv/pubs/facts/afam.htm.