All 50 states, the District of Columbia, U.S. dependencies, possessions, and associated nations* report AIDS cases to CDC by using a uniform case definition and case surveillance report form. This supplemental report includes cases reported according to the CDC guidelines for AIDS case surveillance and the case definition in effect at the time of the report; all cases meet the 1999 surveillance case definition [1].

This report presents the cumulative number of AIDS cases reported during 1981–2004, the number of cases reported during 2004, the case rate (cases per 100,000 population) for 2004, and estimated AIDS prevalence as of December 31, 2004, among adults and adolescents aged 13 years or older, by area of residence at the time of AIDS diagnosis. Rank refers to the number assigned to an area or a metropolitan statistical area (MSA) according to the magnitude of the measure, without consideration for the distance between the values [2]. The lowest rank number was assigned to the highest value of the measure. Ties were resolved by assigning the smallest of the corresponding ranks according to the SAS rank procedure (online documentation for version 8, SAS Institute, Inc., Cary, NC). Because rank indicates a relative position in a series, a rank value is influenced by fluctuations associated with the corresponding area or MSA as well as those of the other sites in the series. Values of 0 were not assigned a rank.

Tables 7–12 represent data for MSAs with a postcensal 2004 estimated population of 500,000 or more. The MSAs, defined by the Office of Management and Budget, were most recently updated in December 2005.

Data in this report were compiled from cases reported to CDC through June 2005. Tables 1–4 and 7–10 present the number of AIDS cases reported to CDC either during 2004 or during 1981–2004; Tables 1 and 7 also present the AIDS case rate (cases per 100,000 population). AIDS prevalence was estimated by adjusting data for delays in the reporting of cases and deaths. In Tables 5, 6, 11, and 12, incidence and prevalence estimates are presented for cases diagnosed through December 2004. These estimates do not represent reported case counts. Rather, these numbers are point estimates, which result from the adjustment of reported case counts. The reported case counts are adjusted for reporting delays and for redistribution of cases in persons initially reported without an identified HIV transmission risk factor [3, 4]. The estimates do not include adjustment for incomplete reporting. These estimates contain an element of uncertainty, and small numbers should be interpreted with caution, as uncertainty in estimates is greater for small numbers.

AIDS case rates presented in Tables 1 and 7 were calculated by using population denominators based on official postcensal estimated 2004 populations from the U.S. Census Bureau [5] and bridged-race estimates from the National Center for Health Statistics. Population denominators for Guam, Puerto Rico, the U.S. Pacific Islands, and the U.S. Virgin Islands were based on postcensal estimated 2004 populations from the U.S. Census Bureau International Data Base. Consistent with the listing in the data sources, the name in the area tables (1–6) is District of Columbia; the name in the MSA tables (7–12) is Washington, DC.

Estimated numbers of AIDS cases in persons exposed through hemophilia/coagulation disorders or receipt of blood transfusion, blood components, or tissue are not presented. The relatively small number of cases in these categories in recent years does not provide information that results in accurate estimates. Similarly, in Tables 11 and 12, estimates are presented only for transmission categories for which there are sufficient numbers at the MSA level. Persons whose transmission category is classified as “high-risk heterosexual contact” are persons who reported specific heterosexual contact with a person with, or at increased risk for, HIV infection (e.g., an injection drug user).

References

1. CDC. Guidelines for national human immunodeficiency virus case surveillance, including monitoring for human immunodeficiency virus infection and acquired immunodeficiency syndrome. MMWR 1999;48(RR-13):1–31.
2. Colton T. Statistics in Medicine. Boston: Little, Brown; 1974:14.
3. Song R, Hall HI, Frey R. Uncertainties associated with incidence estimates of HIV/AIDS diagnoses adjusted for reporting delay and risk redistribution. Stat Med 2005;24:453–464.
4. Neal JJ, Fleming PL, Green TA, Ward JW. Trends in heterosexually acquired AIDS in the United States, 1988 through 1995. J Acquir Immune Defic Syndr Hum Retrovirol 1997;14:465–474.
5. U.S. Census Bureau. Population estimates: entire data set.