Date: Sat, 8 Apr 1995 01:11:08 +0500 From: ghmcleaf{CONTRACTOR/ASPEN/ghmcleaf}%NAC-GATEWAY.ASPEN@ace.aspensys.com Subject: Surveillance Report 12/94 Tech. Notes Technical Notes Surveillance of AIDS All 50 states, the District of Columbia, U.S. dependencies and possessions, and independent nations in free association with the United States1 report AIDS cases to CDC using a uniform surveillance case definition and case report form. The original definition was modified in 1985 (MMWR 1985;34:373-75), in 1987 (MMWR 1987;36[suppl no. 1S]:1S-15S), and again in 1993 (MMWR 1992;41[no. RR-17]:1-19; see also MMWR 1994;43:160-61,167-70). The revisions incorporated a broader range of AIDS-indicator diseases and conditions and used HIV diagnostic tests to improve the sensitivity and specificity of the definition. For persons with laboratory-confirmed HIV infection, the 1987 revision incorporated HIV encephalopathy, wasting syndrome, and other indicator diseases that are diagnosed presumptively (i.e., without confirmatory laboratory evidence of the opportunistic disease). In addition to the 23 clinical conditions in the 1987 definition, the 1993 case definition for adults and adolescents includes HIV-infected persons with CD4+ T-lymphocyte counts of less than 200 cells/uL or a CD4+ percentage of less than 14, and persons diagnosed with pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer. All conditions added to the 1993 definition require laboratory confirmation of HIV infection. Persons who meet the criteria for more than one definition category are classified hierarchically in the following order: pre-1987, 1987, and 1993. Persons in the 1993 definition category meet only the 1993 definition. Although completeness of reporting of diagnosed AIDS cases to state and local health departments varies by geographic region and patient population, studies conducted by state and local health departments indicate that reporting of AIDS cases in most areas of the United States is more than 85 percent complete (J Acquir Immune Def Syndr, 1992;5:257-64 and Am J Public Health 1992;82:1495-99). In addition, multiple routes of exposure, opportunistic diseases diagnosed after the initial AIDS case report was submitted to CDC, and vital status may not be determined or reported for all cases. Surveillance of HIV infection (not AIDS) Through December 31, 1994, 25 states had laws or regulations requiring confidential reporting by name of all persons with confirmed HIV infection, in addition to reporting of persons with AIDS. Two other states, Connecticut and Texas, required reporting by name of HIV infection only for children less than 13 years of age. These states initiated reporting at various times after the development of serum HIV-antibody tests in 1985. Before 1991, surveillance of HIV infection was not standardized and reporting of HIV infections was based primarily on passive surveillance. Consequently, many cases reported before 1991 do not have complete information. Since then, CDC has assisted states in conducting active surveillance of HIV infection using standardized report forms and software. However, collection of demographic and risk information still varies greatly among states. HIV infection data should be interpreted with caution. HIV surveillance reports are not representative of all persons with HIV infection. Because many HIV-reporting states also offer anonymous HIV testing, confidential HIV infection reports are not representative of all persons being tested in these areas. Furthermore, many factors may influence testing patterns, including the extent that testing is targeted or routinely offered to specific groups and the availability and access to medical care and testing services. These data provide a minimum estimate of the number of persons known to be HIV infected in states with confidential HIV infection reporting. For this report, persons greater than 15 months of age were considered HIV infected if they had at least one positive Western blot or positive detection test (culture, antigen, or other detection test) or had a diagnosis of HIV infection documented by a physician. Children less than 15 months of age born to an HIV-infected mother were considered HIV infected if they met the definition stated in the pediatric classification system for HIV infection (see MMWR 1987;36:225-30,235) or were diagnosed as HIV infected by a physician. Although many states monitor reports of children born to infected mothers, among children less than 15 months, only those with documented diagnosis of HIV infection are included in this report. Because states initiated reporting on different dates, the length of time reporting has been in place will influence the number of HIV infection cases reported. For example, data presented for a given annual period may include cases reported during only a portion of the year. Prior to statewide HIV reporting, some states collected reports of HIV infection in selected populations. Therefore, these states have reports prior to initiation of statewide confidential reporting. Over time, persons with HIV infection will be diagnosed and reported with AIDS. HIV infection cases later reported with AIDS are deleted from the HIV infection tables and added to the AIDS tables. Persons with HIV infection may be tested at any point in the clinical spectrum of disease, therefore the time between diagnosis of HIV infection and AIDS will vary. In addition, because surveillance practices differ, reporting and updating of clinical and vital status of cases vary among states. Tabulation and presentation of HIV infection and AIDS data Data in this report are provisional. Each issue of this report includes information received by CDC through the last day of the reporting period. AIDS data are tabulated by date of report to CDC unless otherwise noted. Data for U.S. dependencies and possessions and for associated independent nations are included in the totals. Age group tabulations are based on the person's age at first documented positive HIV-antibody test result for HIV infection cases, and age at diagnosis of AIDS for AIDS cases. Adult/adolescent cases include persons 13 years of age and older; pediatric cases include children under 13 years of age. Age group tabulations for AIDS cases in Table 14 (year-end edition only) are based on age at death. Tabulations of persons living with HIV and AIDS (Table 27, year-end edition only), include persons whose vital status was "alive" as of the last update; persons whose vital status is missing or unknown are not included. Caution should be used in interpreting these data because states vary in the frequency with which they review the vital status of persons reported with HIV infection and AIDS. In addition, some cases may be lost to follow-up. Table 12 (year-end edition only) tabulates AIDS-indicator conditions reported during the last year. These data are known to underreport AIDS-indicator conditions and should be interpreted with caution. Reported conditions overrepresent initial AIDS-indicator illness because follow-up for subsequent indicator diseases is resource intensive and has not been systematic or standardized in most health departments. The 1993 AIDS surveillance case definition for adults and adolescents added reporting of HIV-infected persons with severe HIV-related immunosuppression (CD+ T-lymphocyte count of less than 200/uL or less than 14 percent). Since implementation of the 1993 definition, approximately half of all cases were reported based only on immunologic criteria; consequently, reporting of AIDS cases based on AIDS-defining opportunistic infections has decreased (see AIDS 1994;8:1489-93). Table 2 lists AIDS cases counts for each metropolitan area with 500,000 or more population. AIDS cases counts for metropolitan areas with 50,000 to 500,000 population are reported as a combined subtotal. On December 31, 1992, the Office of Management and Budget announced new Metropolitan Statistical Area (MSA) definitions, which reflect changes in the U.S. population as determined by the 1990 census. These definitions were updated most recently on July 1, 1994. The cities and counties which compose each metropolitan area listed in Table 2 are provided in the publication ~Metropolitan Areas 1994~ (available by calling the National Technical Information Service, 1-703-487-4650, and ordering accession no. PB94-165-628). Standards for defining central and outlying counties of metropolitan areas were published in the Federal Register (see FR 1990;55:12154-60). The metropolitan areas definitions are the MSAs for all areas except the 6 New England states. For these states, the New England County Metropolitan Areas (NECMA) are used. Metropolitan areas are named for a central city in the MSA or NECMA, may include several cities and counties, and may cross state boundaries. For example, AIDS cases and annual rates presented for the District of Columbia in Table 1 include only persons residing within the geographic boundaries of the District. AIDS cases and annual rates for Washington, D.C., in Table 2 include persons residing within the several counties in the metropolitan area, including counties in Maryland, Virginia, and West Virginia. State or metropolitan area data tabulations are based on the person's residence at first positive HIV-antibody test result for HIV infection cases and residence at diagnosis of the first AIDS-indicator condition(s) for AIDS cases. Estimated AIDS-opportunistic illness In 1993, the AIDS surveillance case definition was expanded to include a laboratory measure of severe immunosuppression (CD4+ T-lymphocyte count of less than 200 cells/uL or a percent of total lymphocytes less than 14) and three additional clinical conditions (pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer). Before 1993, the surveillance definition included only opportunistic illnesses, and trends in the incidence of AIDS were evaluated by examining the number of AIDS opportunistic illnesses (AIDS-OIs) diagnosed per year or quarter (adjusted for reporting delays). Because most HIV-infected persons become severely immunosuppressed before the onset of AIDS-OIs, the addition of the CD4+ criteria has temporarily distorted observed trends in AIDS incidence. To examine trends over time, an additional adjustment is required to estimate when an AIDS-OI will develop in persons who were reported based on the CD4+ criteria. CDC has developed a procedure to estimate the incidence of AIDS-OIs among persons reported with AIDS based on the CD4+ criteria. Estimates of trends in AIDS-OIs are displayed in the cover graph and in Tables 18, 19, and 20. The estimated AIDS-OI incidence is the sum of incidence in two groups. The first group is persons reported to AIDS surveillance with AIDS-OIs. Incidence in this group is estimated by adjusting reported cases for delays in case reporting. The second group is persons reported with AIDS based on a CD4+ count or percent. Most of these persons will eventually have an AIDS-OI diagnosed. CDC has estimated the number of persons who had or will have an AIDS-OI diagnosed after the date of the reported CD4+ count or percent, by month of AIDS-OI diagnosis. To do this, CDC used data from the Adult Spectrum of Disease Project (see JAMA 1992;267:1798-1805) to estimate the probability distribution of the time interval between a CD4+ count in a particular range (e.g., 0 to 29 cells/uL, 30 to 59 cells/uL, etc.) and the diagnosis of an AIDS-OI. This probability distribution is the proportion of persons with a CD4+ count in a given range who will have an AIDS-OI diagnosed 1 month, 2 months, etc., after the reported CD4+ count. The expected number of persons with an AIDS-OI diagnosed in each later month among persons whose CD4+ count was in a particular range during a given month is the product of the number of these persons and the proportion expected to have an AIDS-OI diagnosed in this later month. The estimate of the number of AIDS-OI diagnoses in a particular month among persons reported with AIDS based on the CD4+ criteria is the sum, over all combinations of CD4+ ranges and previous months, of the number of persons expected to be diagnosed with an AIDS-OI in the month for which the estimate is made. There is uncertainty in these estimates of AIDS-OI incidence. Some uncertainty is the result of the need to adjust for delays in reporting of AIDS cases. There is additional uncertainty because some persons reported with AIDS based on the CD4+ criteria die before an AIDS-OI is diagnosed and hence should not contribute to the AIDS-OI incidence estimate. Other persons reported with AIDS based on the CD4+ criteria have an unreported AIDS-OI diagnosis by the date of the CD4+ determination; the estimation procedure counts their contribution to AIDS-OI incidence later than it should. However, preliminary analyses show that these two sources of bias change estimated AIDS-OI incidence by only a few percentage points. Reporting delays were estimated by a maximum likelihood statistical procedure, taking into account possible differences in reporting delays among exposure, geographic, racial/ethnic, age, and sex categories, but assuming that reporting delays within these groups have not changed over time (see Lecture Notes in Biomathematics 1989;83:58-88). The curves on the cover graphic were obtained by connecting smoothed values computed for each quarter-year. For each curve, the smoothed value at time t is a weighted average of adjusted incidences in the interval t +/- 1 year; the weights decrease for times further from t. The regions of residence included in Table 18 are defined as follows. Northeast: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont; Midwest: Indiana, Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin; South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia; West: Alaska, Arizona, California, Colorado, Idaho, Hawaii, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming; Territories: Guam, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific Islands listed on page 36. Exposure categories For surveillance purposes, HIV infection cases and AIDS cases are counted only once in a hierarchy of exposure categories. Persons with more than one reported mode of exposure to HIV are classified in the exposure category listed first in the hierarchy, except for men with both a history of sexual contact with other men and injecting drug use. They make up a separate exposure category. "Men who have sex with men" cases include men who report sexual contact with other men (i.e., homosexual contact) and men who report sexual contact with both men and women (i.e., bisexual contact). "Heterosexual contact" cases are in persons who report specific heterosexual contact with a person with, or at increased risk for, HIV infection (e.g., an injecting drug user). Adults/adolescents born, or who had sex with someone born, in a country where heterosexual transmission was believed to be the predominant mode of HIV transmission (formerly classified as Pattern-II countries by the World Health Organization) are no longer classified as having heterosexually acquired AIDS. Similar to case reports for other persons who are reported without behavioral or transfusion risks for HIV, these reports are now classified (in the absence of other risk information which would classify them into another exposure category) as "no risk reported or identified" (see MMWR 1994;43:155-60). Children whose mother was born, or whose mother had sex with someone born, in a Pattern-II country are now classified (in the absence of other risk information which would classify them into another exposure category) as "Mother with/at risk for HIV infection: has HIV infection, risk not specified." "No risk reported or identified" cases are in persons with no reported history of exposure to HIV through any of the routes listed in the hierarchy of exposure categories. Risk not identified cases include persons who are currently under investigation by local health department officials; persons whose exposure history is incomplete because they died, declined to be interviewed, or were lost to follow-up; and persons who were interviewed or for whom other follow-up information was available and no exposure mode was identified. Persons who have an exposure mode identified at the time of follow-up are reclassified into the appropriate exposure category. In general, investigations and follow up for modes of exposure by state health departments are conducted routinely for persons reported with AIDS and as resources allow for those reported with HIV infection. Therefore, the percentage of HIV infected persons with risk not reported or identified is substantially higher than for those reported with AIDS. Rates Rates are calculated on a 12-month basis per 100,000 population for AIDS cases only. Rates are not calculated for HIV infection reports because case counts for HIV infection are believed to be less complete than AIDS case counts. Population denominators for computing AIDS rates for the 50 states and the District of Columbia are based on official post-census estimates from the U.S. Bureau of Census. Denominators for U.S. dependencies and possessions are linear extrapolations of official 1980 and 1990 census counts. Each 12-month rate is the number of cases reported during the 12-month period, divided by the 1993 or 1994 population, multiplied by 100,000. The denominators for computing race-specific rates (Table 10, year-end edition only) are based on 1990 census projections published in U.S. Bureau of Census publication P25-1092, "Population Projections of the United States, by Age, Sex, Race, and Hispanic Origin: 1992 to 2050." Race-specific rates are the number of cases reported for a particular racial/ethnic group during the preceding 12-month period divided by the projected population for that race/ethnicity, multiplied by 100,000. Case-fatality rates are calculated for each half-year by date of diagnosis of AIDS. Each 6-month case-fatality rate is the number of deaths ever reported among cases diagnosed in that period (regardless of the year of death), divided by the number of total cases diagnosed in that period, multiplied by 100. Reported deaths are not necessarily caused by HIV-related disease. Caution should be used in interpreting case-fatality rates because reporting of deaths is incomplete (see Am J Public Health 1992;82:1500-05 and Am J Public Health 1990;80:1080-86). Reporting delays Reporting delays (time between diagnosis of HIV infection or AIDS and report to CDC) vary widely among exposure, geographic, racial/ethnic, age and sex categories, and have been as long as several years for some AIDS cases. About 50 percent of all AIDS cases were reported to CDC within 3 months of diagnosis, with about 20 percent being reported more than one year after diagnosis. Reporting delay for HIV infection cases is being evaluated.