Reports on HIV/AIDS: 1990

NOVEMBER 30, 1990, MMWR, Vol. 39, RR-16 [Inclusive page numbers]
Trends in AIDS incidence
Slowing of the rapid upward trend in AIDS incidence that occurred in 1987 has
influenced current HIV-prevalence estimates and AIDS case projections (10). The
number of AIDS cases diagnosed per month continued to increase in 1987, but the
rate of increase declined in the middle of that year, particularly among homosexual
and bisexual men who did not use intravenous drugs (Figure 1). Among that group,
the change in trends was most apparent in New York City, San Francisco, and Los
Angeles (Figure 2). The trend in incidence also appears to have changed during 1987
among white homosexual men outside these cities, with no change in the trend
among all other categories of homosexual men, most of whom are black or Hispanic
(Figure 3; only the smoothed trends in monthly incidence are shown in this figure).
The factors considered by the workshop participants as reasons for this change
included the following: a) a decline in the incidence of new HIV infections among
homosexual men in the early 1980s, leading to a subsequent decline in the incidence
of reported AIDS cases ( 11 ); b) the use of antiretroviral and other types of therapy by
mid-1987, leading to a lengthening of the incubation period from the acquisition of
HIV infection to the presence of symptoms of AIDS; and c) possible decreases in the
completeness or timeliness of AIDS case reporting. The accuracy of HIV-prevalence
estimates and AIDS case projections depends in part on the determination of the
relative contribution of these or other factors.
Data related to two of these factors-completeness of reporting and effect of
therapy-became available after the workshop. Analysis of preliminary data on
mortality for 1988 did not indicate less complete reporting of AIDS cases in 1987 and
1988 than before 1987 (see Appendix A). The availability of data on the use of
zidovudine (formerly called AZT) in mid-1987 made it possible to estimate the effect
Figure 1. Acquired immunodeficiency syndrome (AIDS) cases, United States, January
1985-June 1989
4,000 -A - All Cases A
H - Homosexual/Bisexual Men
3000 0 All Other Cases A
3.000 A
AAA A
cis
O
5 2,000 H H
A H H H
A r H H O
170
A A H HH H 0 0 0 0
1.000 A AA H H
H O
0 0
0 1985. 1986. 1987. 1988. 1989
Month and Year of Diagnosis
*Adjusted for reporting delays.

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