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.
References
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).
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.
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