Current Trends Update: Acquired Immunodeficiency Syndrome -- United States, 1981-1988
In 1988, state and local health departments reported 32,311 persons (28,432 men, 3296 women, and 583 children (less than 13 years of age)) diagnosed with illnesses that meet the CDC case definition for acquired immunodeficiency syndrome (AIDS) (1) in the United States and its territories. Excluding U.S. territories, these persons represent an annual incidence rate of 13.7 AIDS cases per 100,000 population: 31.2 cases per 100,000 men, 3.2 cases per 100,000 women, and 1.3 cases per 100,000 children.*
During this period, blacks and Hispanics had the highest annual incidence rates per 100,000 population (34.9 and 28.9, respectively), followed by whites (9.6), Asians/Pacific Islanders (5.4), and American Indians/Alaskan Natives (2.2).
As of December 31, 1988, a total of 82,764 AIDS cases had been reported to CDC. The number of AIDS cases reported each year continues to increase; however, the rate of increase has steadily declined, except in 1987, when the revision of the case definition resulted in an abrupt increase in reported cases (Figure 1).
Impact of the 1987 revision of the AIDS case definition. In September 1987, the CDC AIDS case definition was revised for persons with laboratory evidence of human immunodeficiency virus (HIV) infection (e.g., positive HIV-antibody test) to include a broader spectrum of diseases characteristically found in persons with HIV infection and the presumptive diagnosis of selected diseases. The revision has markedly affected the distribution of reported cases.
Of the 40,836 cases reported between September 1987 and December 1988, 11,966 (29%) met only the 1987 revision. Of these persons, 3949 (33%) had a presumptive diagnosis of Pneumocystis carinii pneumonia, 3904 (33%) had HIV wasting syndrome, 1781 (15%) had HIV dementia, 1639 (14%) had a presumptive diagnosis of esophageal candidiasis, and 737 (6%) had extrapulmonary tuberculosis (658 definitively diagnosed and 79 presumptively diagnosed). Compared with patients with illnesses meeting the pre-1985 (2) or the 1985 (3) case definitions, a higher proportion of patients reported since September 1987 with illnesses meeting only the 1987 case definition were female (15% compared with 9%), black or Hispanic (34% and 21%, respectively, compared with 26% and 14%, respectively), or heterosexual intravenous-drug users (IVDUs) (35% compared with 18%). A lower proportion of those meeting only the 1987 case definition had a history of male homosexual/bisexual activity without IV-drug use (41% compared with 63%).
Geographic distribution. AIDS cases have been reported from all 50 states, the District of Columbia, and four U.S. territories. Annual incidence rates by state for 1988 varied from 0.6 cases per 100,000 persons in North Dakota to 38.9 per 100,000 in New York (Figure 2).
The geographic distribution of AIDS cases has shifted over time. Before 1984, the Mid-Atlantic region of the United States (New Jersey, New York, and Pennsylvania) reported 54% of all AIDS cases (52% of men and 73% of women with AIDS). In 1988, the Mid-Atlantic region reported only 32% of all AIDS cases (29% of men and 50% of women with AIDS) (Figure 3). Before 1984, 47% of all male patients with histories of homosexual/bisexual activity were reported from the Mid-Atlantic region; in 1988, 21% of these men were reported from the Mid-Atlantic region.
The proportion who had histories of IV-drug use without homosexual activity from this region also decreased, from 85% to 59%. The proportion of all cases from all other regions increased during this period, except for the Pacific** region, which remained stable. Increases were greatest in the East North Central, South Atlantic, and West South Central regions.**
Men. Of the 82,764 AIDS cases reported to CDC as of December 31, 1988, 74,435 (90%) were in males greater than or equal to13 years of age. The mean age at the time of diagnosis was 37.0 years. A total of 61.0% were white (non-Hispanic); 23.7%, black (non-Hispanic); 14.5%, Hispanic; 0.6%, Asian/Pacific Islander; and 0.1%, American Indian/Alaskan Native.
This distribution has remained stable over time, except for a decrease in the proportion of men who were white (from 64% in 1987 to 57% in 1988) and an increase in the proportion that was black and Hispanic (from 22% and 12%, respectively, in 1987 to 25% and 16% in 1988), reflecting the 1987 revision of the case definition. The cumulative incidence of AIDS between 1981 and 1988 was 3.0 times higher among black men and 2.8 times higher among Hispanic men than among white men.
Sixty-eight percent of men with AIDS had histories of homosexual/bisexual activity without IV-drug use, 17% had IV-drug use without homosexual/bisexual activity, and 8% had both homosexual activity and IV-drug use. Another 2% had histories of blood transfusion, 1% had hemophilia or other coagulation disorder, 1% had sex partners at increased risk for or known to be infected with HIV, 1% were born in countries with predominantly heterosexual transmission of HIV (4), and 3% had undetermined means of exposure to HIV.
This distribution has remained stable, except for a decrease in the proportion of men with histories of homosexual/bisexual activity without IV-drug use (from 70% of those reported in 1987 to 63% of those reported in 1988) and an increase in the proportion with histories of IV-drug use and no homosexual/bisexual activity (from 14% in 1987 to 20% in 1988), again partially reflecting the 1987 revision of the case definition. This trend was most evident in the Mid-Atlantic region, where the proportion of homosexual/bisexual men without IV-drug use decreased from 54% to 46% and the proportion of heterosexual IVDUs increased from 34% to 41%.
In addition, the proportion of all men with AIDS born in countries with predominantly heterosexual transmission of HIV decreased from 4% before 1984 to 1% in 1988. Black and Hispanic men with AIDS were more likely to have had histories of IV-drug use and less likely to have had histories of homosexual activity than white men (Table 1).
Women. As of December 31, 1988, 6983 AIDS cases have been reported among females greater than or equal to13 years of age, constituting 8% of all AIDS cases. This proportion increased from 8% of reported cases in 1987 to 10% of reported cases in 1988. The mean age at diagnosis was 35.7 years; 51.6% were black; 27.9%, white; 19.5%, Hispanic; 0.6%, Asian/Pacific Islander; and 0.2%, American Indian/Alaskan Native.
This distribution has been relatively stable. The cumulative incidence of AIDS between 1981 and 1988 was 13.6 times higher among black women and 10.2 times higher among Hispanic women than among white women. Among women with AIDS, 52% had histories of IV-drug use, 18% had sex partners with histories of IV-drug use, 7% had sex partners otherwise at increased risk for or known to be infected with HIV, 11% had histories of blood transfusion, 4% were born in countries with predominantly heterosexual transmission of HIV (4), and 8% had undetermined means of exposure.
The proportion of women with AIDS who had sex partners at increased risk for HIV rose from 15% before 1984 to 26% in 1988, and the proportion born in countries with predominantly heterosexual transmission decreased from 11% to 3%. Black and Hispanic women with AIDS were more likely than white women to have had histories of IV-drug use or histories of sex with IVDUs (Table 1).
Children. As of December 31, 1988, 1346 AIDS patients less than 13 years of age had been reported to CDC. Of these, 55% were male. Eighty-two percent of pediatric patients were less than 5 years of age at diagnosis, and 40% were less than 1 year of age.
Racial distribution among pediatric patients was similar to that among women with AIDS: 52.5% were black; 23.9%, white; 22.9%, Hispanic; 0.5%, Asian/Pacific Islander; and 0.2%, American Indian/Alaskan Native. Among pediatric patients, 78% are presumed to have acquired HIV infection perinatally from their mothers, 13% from blood transfusion, and 6% from blood products used to treat hemophilia. Four percent had undetermined means of exposure to HIV. Of those infected from their mothers, maternal risk factors included IV-drug use (54%), sex with an IVDU (19%), sex with a man otherwise at increased risk for or infected with HIV (7%), birth in a country with predominantly heterosexual transmission (11%), and transfusion (2%). The mothers' risk factors were not reported in 7%.
The proportion of perinatally infected children whose mothers had sex partners at increased risk for or infected with HIV (including IVDUs) rose from 11% of all pediatric cases before 1985 to 21% in 1988; the proportion of those whose mothers were born in countries with predominantly heterosexual transmission decreased from 22% to 7%. Black and Hispanic pediatric patients were more likely to have had mothers with histories of IV-drug use or of sex with IVDUs than were white children (Table 1).
Patients with no identified risk factor. AIDS patients initially reported as having undetermined means of exposure to HIV are investigated by local or state health officials for a possible means of exposure. Overall, 2706 (3%) reported AIDS cases fall into this category; this percentage has remained stable, except for an increase to 5% in 1988. This greater proportion of patients with no identified risk factor in the most recent reporting periods reflects the large number of cases still under investigation. Of all AIDS patients initially reported to CDC with undetermined means of exposure, 83% have been reclassified into a known exposure category when follow-up information was obtained. Therefore, many of the persons reported in 1988 with no identified risk factor will be reclassified after additional information becomes available.
In general, patients with no identified risk factor are not characteristic of the U.S. population: 79% are male, 39% are white (compared with 80% of the U.S. population), and 90% are 20-59 years of age (compared with 54% of the U.S. population). Of the 2706 patients currently listed as having undetermined means of exposure, investigations were not completed for 11% due to death, 4% due to refusal to be interviewed, and 2% due to loss to follow-up. Of the remaining 2231 patients, 1892 are under investigation, and 339 had no risk factor identified after investigation.
Among the latter, many had histories of a sexually transmitted disease other than AIDS and/or reported sexual contact with prostitutes and may have been at increased risk for HIV infection because of sexual activity. Investigations have revealed no evidence of new modes of transmission of HIV. Mortality. Fifty-six percent of all AIDS patients (56% of adults/adolescents and 55% of children) and 85% of those diagnosed before 1986 are reported to have died. The actual case-fatality rate is higher due to incomplete reporting of deaths.
In 1987, HIV infection/AIDS ranked 15th among leading causes of death in the United States (5) and seventh among all causes of years of potential life lost (6). Deaths occurring in 1987 among persons with AIDS that were reported to CDC represented 9% of all deaths among persons 25-34 years of age and 7% of all deaths among persons 35-44 years of age. Reported by: Local, state, and territorial health departments. AIDS Program, Center for In- fectious Diseases, CDC.
National surveillance of AIDS encompasses severe diseases thought to be highly specific for HIV infection. CDC first outlined a surveillance case definition in 1982 (7), which was modified in 1983 (2).
As knowledge about HIV infection increased, other severe and commonly occurring manifestations of HIV infection were included in the case definition in 1985 (3) and again in 1987 (1). Additions included disseminated histoplasmosis, chronic isosporiasis, and certain non- Hodgkins lymphomas (1985 revision) and extrapulmonary tuberculosis, HIV encephalopathy, HIV wasting syndrome, multiple or recurrent bacterial infections (in children only), and presumptively diagnosed Pneumocystis carinii pneumonia and esophageal candidiasis (1987 revision). In both instances, the revision applied to patients with laboratory evidence (e.g., positive antibody test) for HIV infection.
The number of AIDS cases increased 3%-4% as a result of the 1985 revision. The 1987 revision has had an even greater effect. Studies in selected groups and areas suggest that the number of cases may increase as much as 22% among homosexual men (8) and persons with hemophilia (9) and even more among pediatric patients (10). Therefore, the increase in the number of cases reported in 1987 and 1988 reflect, at least in part, the revision of the case definition. The long-term effects of the revised case definition on surveillance trends are not clear-cut because 1) HIV testing and the revised case definition are not used uniformly in all populations, 2) diagnostic practices for specific AIDS-indicator diseases may be changing, and 3) some patients with illnesses initially meeting only the 1987 case definition may eventually develop illnesses meeting the previous case definition.
AIDS incidence is highest in the most populous metropolitan areas in the United States. Standard metropolitan statistical areas (SMSAs) with greater than 1 million residents comprise 41% of the U.S. population but accounted for 75% of U.S. AIDS cases between 1981 and December 1988. This distribution of cases, however, is changing, as reflected in the decrease in the proportion of cases reported from the Mid-Atlantic region.
The proportion of AIDS cases from SMSAs with less than or equal to 500,000 population in- creased from 12% before 1986 to 19% in 1988. Such findings are important in the development of prevention strategies and suggest that HIV prevention activities should be conducted in areas with smaller populations, as well as in large metropolitan areas. Blacks and Hispanics continue to be disproportionately represented among AIDS patients, particularly among those who were IVDUs or sex partners or children of IVDUs.
In 1988, the annual incidence rate of AIDS cases associated with IV-drug use was 11.5 times higher among blacks and 8.8 times higher among Hispanics than among whites (11). This difference was even more dramatic in the Northeast. Although the racial/ethnic distribution of IVDUs in the United States is unknown, a 1982 National Institute on Drug Abuse survey of drug-abuse treatment centers suggests that a disproportionate number of IVDUs attending treatment clinics in high AIDS-incidence areas were black or Hispanic (12).
Furthermore, HIV seroprevalence rates are higher among black and Hispanic IVDUs than among white IVDUs (13,14), except on the West Coast. These findings emphasize the need for community-based HIV prevention programs in areas with a high prevalence of drug use, especially among minorities. These programs should include HIV educational programs and counseling and testing facilities in drug-treatment centers, sexually transmitted disease clinics, tuberculosis clinics, jails and prisons, and health-care facilities.
*Based on 1980 census data.
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