Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

Impact of the Expanded AIDS Surveillance Case Definition on AIDS Case Reporting -- United States, First Quarter, 1993

On January 1, 1993, the acquired immunodeficiency syndrome (AIDS) surveillance case definition for adolescents and adults was expanded beyond the surveillance definition published in 1987 (1) to include all human immunodeficiency virus (HIV)-infected persons with severe immunosuppression ( less than 200 CD4+ T-lymphocytes/uL or a CD4+ T-lymphocyte percentage of total lymphocytes of less than 14), pulmonary tuberculosis (TB), recurrent pneumonia, or invasive cervical cancer. This report reviews AIDS surveillance reports CDC received from local, state, and territorial health departments during the first quarter of 1993 and summarizes the impact of the changes in the AIDS surveillance case definition.

From January 1 through March 31, a total of 35,779 AIDS cases -- 13% of the cumulative total of 284,840 AIDS cases reported since 1981 -- were reported to CDC, representing a 204% increase over the number reported for the same period in 1992 (11,770 cases) (Figure 1). Forty-eight states and Puerto Rico reported cases based on the criteria added to the surveillance definition in 1993.

Of the 35,779 AIDS cases, 21,582 (60%) were reported based on the conditions added in 1993, and 14,197 (40%) were reported based on pre-1993-defined conditions -- a 21% increase in reporting of pre-1993-defined cases over the number reported for the same period in 1992. Of the cases reported with only 1993-added conditions, 19,284 persons (89%) had severe HIV-related immunosuppression only; 2021 (9%) had pulmonary TB; 245 (1%), recurrent pneumonia; and 41 (less than 1%), invasive cervical cancer. *

Implementation of the expanded surveillance definition has been associated with an increase in the median interval between date of diagnosis and date of report of AIDS cases; in preceding years, this interval had been 3 months. In contrast, persons with conditions added in 1993 had a median interval between date of diagnosis and date of report of 9 months, and persons with pre-1993 conditions reported in the first quarter of 1993, 5 months.

Reported by: Local, state, and territorial health depts. Div of HIV/AIDS, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The findings in this report indicate that an immediate impact of the revised AIDS surveillance case definition on case reporting has been a substantial increase in the number of reported AIDS cases. The increase in the first quarter of 1993 is not expected to be sustained because the increase in cases reported during this period reflects predominantly the reporting of the accumulated number of persons with previously diagnosed conditions added to the surveillance definition in 1993 who could not be reported as AIDS cases until January 1, 1993. The interval between date of diagnosis and date of report for persons with 1993-added conditions indicates that AIDS cases in these persons were diagnosed earlier than in other persons reported with AIDS.

CDC has estimated that the number of AIDS cases reported during 1993 will increase approximately 75% as a result of the expanded reporting criteria (2). The increase in the number of persons reported with pre-1993 conditions during this quarter probably reflects changes in surveillance procedures associated with implementation of the 1993 surveillance definition. CDC will continue to report on the ongoing evaluation of surveillance findings and the impact of the expanded AIDS surveillance case definition.


  1. CDC. 1993 Revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. MMWR 1992;41(no. RR-17).

  2. CDC. Projections of the number of persons diagnosed with AIDS and the number of immunosuppressed HIV-infected persons -- United States, 1992-1994. MMWR 1992;41(no. RR-18).

    • The total number of diagnosed 1993-added conditions (i.e., pulmonary TB, recurrent pneumonia, and invasive cervical cancer) is greater than the total number of persons with these conditions because nine persons were reported with more than one condition.

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Page converted: 09/19/98


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services

This page last reviewed 5/2/01