AIDS Cases Diagnosed in 1997 and 1998
By Sex, Race/Ethnicity, Age at Diagnosis, and Risk Exposure

Technical Notes

AIDS cases are reported to CDC by all 50 states, the District of Columbia, U.S. dependencies, U.S. possessions, and independent nations in free association with the United States⁽¹⁾ by the use of a uniform case definition and case surveillance report form. Cases in this report were reported according to the 1993 expanded surveillance case definition (MMWR 1992;41 [RR-17]:1-19).

Based on data reported to CDC through June 30, 1999, this report presents estimates of AIDS incidence for adults and adolescents 13 years of age or older diagnosed with AIDS in 1997 and 1998. Data have been adjusted for delays in reporting and redistribution of cases reported with no identified risk (NIR).

Reporting delay adjustments to estimated AIDS data are calculated by a maximum likelihood statistical procedure, taking into account differences in reporting delays among categories -- exposure, geographic, racial/ethnic, age, sex, and vital status -- but assuming no reporting delay changes over time (Statist Med 1998;17:143-54 and Lecture Notes in Biomathematics 1989;83:58-88).

Adjustment for redistribution of NIR cases is based on sex-, race-, and region-specific exposure category redistributions of cases diagnosed from 1990 through 1997 that were initially assigned to the NIR category but subsequently have been reclassified. (J Acquir Immune Def Syndr, 1992;5:547-55 and J Acquir Immune Def Syndr, 1997;14:465-74).

Age-group classification is based on a person's age at the time of AIDS diagnosis. The exposure category labeled "Other" includes persons exposed to HIV-infected blood, body fluids, or concentrated virus in health care, laboratory, or household settings; persons who acquired HIV infection perinatally but were diagnosed with AIDS after age 13; and persons who lacked available information for reclassification into an exposure category. Percent totals may not equal 100 due to rounding.

1. Included among the dependencies, possessions, and independent nations are Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, the Republic of Palau, the Republic of the Marshall Islands, and the Federated States of Micronesia.