HIV/AIDS surveillance report : U.S. HIV and AIDS cases reported June 1998
Corporate Authors:National Center for HIV, STD, and TB Prevention (U.S.). Division of HIV/AIDS Prevention.
Series:HIV/AIDS surveillance ; v. 10, no. 1
Description:Midyear edition, Vol. 10, No. 1.
Through June 1998, 665,357 persons with AIDS have been reported to CDC. Continuing the pattern first observed from 1995 to 1996, AIDS incidence decreased again from 1996 to 1997. These decreases are mostly due to the effective therapies for HIV and AIDS that have altered the natural history of HIV infection, and slowed progression to AIDS. AIDS incidence increasingly represents persons who were not diagnosed with HIV infection until they developed AIDS, people who did not access treatment, or people for whom treatment failed. As a result, the ability of AIDS surveillance data to represent the characteristics of affected populations and project the need for prevention and treatment has diminished, and information from HIV infection surveillance in addition to AIDS is becoming increasingly important to monitor the epidemic. For this reason, starting with this edition of the HIV/ AIDS Surveillance Report, information from HIV infection and AIDS case surveillance are presented in an integrated format.
Although the HIV tables and the AIDS tables are now presented side-by-side (e.g., tables 5 and 6), they cannot be directly compared because the HIV tables represent only those states that currently report cases of HIV infection, whereas the AIDS tables represent all states. Differences in distribution of risk, for example, may reflect differences between the epidemics in states that report HIV and those that do not. In addition, HIV surveillance data should be interpreted with knowledge of local practices because they are influenced by the availability of HIV test facilities and the proportion of HIV-infected persons who seek or defer testing. CDC estimates that the majority of infected persons in the United States have been tested. The proportion of infected persons tested is expected to increase and the representativeness of the HIV data will increase accordingly. Persons are counted only once in the HIV/AIDS surveillance system; persons who are reported with HIV and with AIDS are counted only as AIDS cases.
The proportion of cases initially reported without risk information has increased, making it more difficult to interpret the risk information for recently reported cases. To compensate for this, selected tables include an adjustment for unreported risk, referred to in the tables as redistribution of risk. Recent AIDS incidence in some categories, especially heterosexual contact, will be under-estimated unless an adjustment is made. To make the data presented in tables 9, 11, and 13 more readily interpretable, these data are now presented with this adjustment in tables 20, 21, and 22. Because the adjustment is done according to year of diagnosis rather than year of report, tables 20, 21, and 22 represent persons diagnosed from January through December 1997, rather than persons reported from July 1997 through June 1998. Methods to estimate risk among HIV infection cases initially reported without risk are currently being developed. In future editions of the report, corresponding tables for HIV infection cases will be included.
Since 1994, this report has provided estimated trends in AIDS opportunistic illnesses (AIDS-OI) incidence. The procedure to estimate AIDS-OI incidence was developed to take into account the 1993 expansion of the case definition which temporarily distorted the AIDS incidence curve. By 1996 the temporary distortion had almost entirely waned and AIDS-OI incidence was similar to AIDS incidence. In addition, since the end of 1996, the incidence of AIDS-OIs can no longer be reliably estimated because data are not currently available to model the increasing effects of therapy on the rate of disease progression. As a result, this report presents trends in annual AIDS incidence starting in 1996, rather than estimated AIDS- OIs. These changes in the method of monitoring trends do not affect pediatric AIDS incidence because the 1993 expansion of the AIDS case definition affected only adult/adolescent cases, not pediatric cases. Figure 11 shows pediatric AIDS incidence from 1992 to 1997.
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