Source of AIDS Surveillance Data

CDC maintains national AIDS surveillance through receipt of AIDS case reports submitted by individual state and local health departments. Health departments report cases electronically through a CDC-developed microcomputer system. All 50 states, the District of Columbia, U.S. dependencies and possessions, and independent nations in free association with the United States (Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, the Republic of Palau, the Republic of the Marshall Islands, the Commonwealth of the Northern Mariana Islands, and the Federated States of Micronesia) report AIDS cases to CDC.

Although state and local health departments share AIDS surveillance data with CDC, the responsibility and authority for AIDS surveillance rests with the individual health departments. Like any reportable disease, the completeness of AIDS reporting reflects how actively health departments solicit case reports. Historically, disease surveillance systems have been categorized as passive or active, i.e., health departments may passively receive case reports from health care providers, depending on health care providers to know and comply with reporting requirements; or they may actively contact and interact with health care facilities or individual providers to stimulate disease reporting, sometimes directly assuming the primary responsibility of reporting cases from large or high-volume institutions.

CDC provides funding and technical assistance to health departments to actively stimulate AIDS case reporting and has encouraged them to take an active rather than passive approach to AIDS surveillance. Through surveillance cooperative agreements supported by CDC, health departments are encouraged to identify health care facilities that serve AIDS patients and work closely with these facilities to encourage reporting. They are also encouraged to send newsletters to health care providers and attend professional organization meetings, and to use other data sources to identify AIDS cases, including death certificates, laboratory reports, and tuberculosis and tumor registries. States vary in the structure and organization of their surveillance systems and, therefore, in the completeness of their case reporting (see below).

Case Definition

Before HIV was identified as the etiologic agent for AIDS, CDC defined a case of AIDS (for surveillance purposes) as a disease, at least moderately indicative of a defect in cell-mediated immunity, occurring in a person with no known cause for diminished resistance to the disease. Such diseases included Pneumocystis carinii pneumonia, Kaposi's sarcoma, and many other serious opportunistic infections (see American Journal of Medicine, March 1984, pages 493-500). With identification of HIV as the causative agent for AIDS and the availability of laboratory tests to detect HIV antibody, the case definition was expanded to reflect an increased understanding of HIV infection in 1985 (see CDC's Morbidity and Mortality Weekly Report, June 28, 1985, pages 373-375) and in 1987 (see Morbidity and Mortality Weekly Report, August 14, 1987, supplement, pages 3S-15S). These revisions applied to persons with laboratory evidence for HIV infection. Among diseases added in 1985 were disseminated histoplasmosis, chronic isosporiasis, and certain non-Hodgkin's lymphomas. Among those added in 1987 were extrapulmonary tuberculosis, HIV encephalopathy, and HIV wasting syndrome. In children, recurrent, serious bacterial infections were also added. In addition, the 1987 revision allowed certain indicator diseases to be diagnosed presumptively based on clinical presentation rather than "confirmed" by laboratory or diagnostic methods.

To be consistent with standards of medical care for HIV-infected persons and to more accurately reflect the number of persons with severe HIV-related immunosuppression who are at highest risk for HIV-related morbidity and most in need of close medical follow-up, the surveillance definition was expanded on January 1, 1993 (see CDC's Morbidity and Mortality Weekly Report, Recommendations and Reports, December 18, 1992). This expansion includes all HIV-infected adults and adolescents who have less that 200 CD4⁺ T-lymphocytes/µL or a CD4⁺ T-lymphocyte percent of total lymphocytes less than 14, or who have been diagnosed with pulmonary tuberculosis, invasive cervical cancer, or recurrent pneumonia. The addition of pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer in HIV-infected adults and adolescents to the 23 clinical conditions listed in the 1987 surveillance definition reflects their documented or potential importance in the HIV epidemic.

While the reported incidence of AIDS increased only 3 to 4 percent as a result of the 1985 revision, the 1987 revision greatly increased the numbers of reported cases. Roughly one fourth of all adults/adolescents who were both diagnosed and reported in the year following the 1987 revision were reported based only on the additional criteria included in the 1987 revision. Furthermore, the proportion of cases meeting only the revised criteria was higher in Hispanics and non-Hispanic blacks than in non-Hispanic whites, higher in heterosexual injecting drug users, and lower in men who have sex with men. The 1993 revision has had substantial impact on the number of reported cases. The immediate increase in case reporting was largely attributed to the addition of severe immunosuppression to the definition; a smaller impact was due to the addition of pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer, since many persons with these diseases also have a CD4⁺ T-lymphocyte count of less than 200 cells/µL. The early effects of expanded surveillance were greater than long-term effects because prevalent as well as incident cases of immunosuppression were reported after implementation of the expanded surveillance case definition. In recent years, the effect on the number of reported cases has been smaller. Due to the large number of cases reported based on criteria in only the revised case definitions and to the inconsistent use of the revised case definitions in different populations, analyses of trends in AIDS cases must take these revisions into account.

Case report form

Separate case report forms are used for pediatric patients (patients less than 13 years of age at the time of diagnosis) and adult/adolescent patients (patients 13 years of age or older at the time of diagnosis). Although the forms are similar, the pediatric form includes behavioral risk information on the child's mother. These forms are completed by the health care provider or by the AIDS surveillance staff in the local or state health department. In addition, a laboratory report of an AIDS-defining condition sent to health departments may initiate a case report. In these cases, follow-up with the health care provider is required to obtain complete information.

Names are retained by the state or local health department and are converted to an alpha-numeric code called “soundex” for use by CDC. CDC does not receive names of persons with AIDS. Because more than one state may report an individual case, CDC screens reported cases by soundex code, date of birth, sex, and state of residence to cull presumed duplicate reports. States also cooperate in this process by reporting out-of-jurisdiction cases to the patient's state of residence.

The variables available on the AIDS data set are listed in the next section. However, a few deserve special comment.

• Vital status. Patients survive for a variable amount of time following the diagnosis of AIDS. Because death usually occurs after the initial report to CDC, case reports may not be updated to reflect the change in vital status. As a result, reporting of deaths among AIDS patients may be delayed or incomplete. However, states are required to perform periodic reviews of death certificates and state death registries to identify unreported cases, and to update vital status of known cases. In addition, 16 states participated in a special project to match their case registries to the National Death Index to assess the completeness of reporting and to identify deaths among cases that died out-of-jurisdiction.
   

• Exposure category. Some patients may have more than one mode of exposure to HIV. For surveillance purposes, AIDS cases are counted only once in a hierarchy of exposure categories. Persons with more than one reported mode of exposure are listed in the category that appears first in the exposure 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.
   

• AIDS definition category. Patients may develop additional conditions indicative of AIDS after their initial AIDS diagnosis. The case report form may not be updated to reflect additional conditions. Some persons reported as meeting only the immunologic criteria may have concurrent or prior opportunistic infections or conditions that are not included in the case report. Therefore, cases reported as meeting only the criteria added to the case definition in 1993 may include persons who meet the criteria in 1987 definition.
   

• Date of diagnosis. CDC collects dates of diagnosis for each AIDS-indicator disease, and, for patients with severe immunosuppression, the date of the CD4⁺ T-lymphocyte test. From this information, a single date of diagnosis is calculated for each patient; it is the earliest of these dates.

Delay in Reporting

The timeliness of AIDS case reporting to CDC is dependent on a number of factors, including the volume of cases reported from a state or locality, the cooperation of health care providers and medical institutions, the availability of staff to complete case report forms, and changes in the case definition. In many instances initial case reports are incomplete and require additional follow-up by state and local health department staff, including reviews of other record systems and contact with health care providers.

Based on estimates calculated using AIDS surveillance data reported between 1995 and 2000, about 50 percent of all cases were reported to CDC within 4 months of the date of diagnosis, but about 20 percent were reported more than 1 year after diagnosis. Delays vary widely among geographic, age, exposure, sex, and racial/ethnic categories. They are substantially longer for pediatric cases and shorter for AIDS cases previously reported with HIV infection, for example. Due to the reporting delay, the number of cases diagnosed during any period often exceeds the number reported during that period. This is particularly important in examining trends over time, since many cases in recent periods of time will not yet be reported.

To account for delays in the reporting of cases, the variable adjwgt is included in the data set. This variable may be used to weight each case on the data set and obtain adjusted case counts. For example, summing adjwgt for cases would estimate the number of cases diagnosed through the time period covered by the data set that will eventually be reported to CDC. To use this variable, select the adjustment weight option from the Tools menu. Once you turn the option on, all subsequent tabulations will be adjusted for reporting delay. The adjustment weight and resulting tabulations are not reliable for cases diagnosed during the most recent 6 to 9 months.

Effect of CD4 Reporting on AIDS Case Trends

As a result of the case definition change in 1993, trends in AIDS case counts showed an artifactual peak early in 1993, even after adjustment for reporting delay. To examine trends over time using
a constant case definition, i.e., diagnoses of opportunistic illnesses that were included in the 1987 or the 1993 case definition, CDC developed methods that estimated incidence of 1987 or 1993 definition opportunistic infections for cases that met only the 1993 immunologic (CD4⁺) criteria. These estimates showed that the number of diagnoses of AIDS-defining opportunistic infections increased during 1992 and 1993 by approximately 2 percent and 3 percent, respectively (see Morbidity and Mortality Weekly Report, November 18, 1994). The temporary distortion of the AIDS incidence curve caused by the 1993 expansion of the AIDS case definition had almost entirely waned by 1996.

Effect of Therapy on AIDS Incidence

Continuing the pattern first observed from 1995 to 1996, AIDS incidence decreased again from 1996 to 1997 and from 1997 to 1998. These decreases are mostly due to the effect of therapies for HIV infection and AIDS, which have altered the natural history of HIV infection and slowed progression to AIDS. AIDS incidence increasingly represents persons who were not diagnosed with HIV infection until they developed AIDS, persons who did not access treatment, or persons for whom treatment failed. Caution should be used when interpreting trends in AIDS incidence; the contribution of these effects to the AIDS incidence curve is currently being evaluated. See Morbidity and Mortality Weekly Report, September 19, 1997 and April 24, 1998.

Early Reporting Dates

Before 1990, CDC occasionally received reports on patients before they met the CDC AIDS case definition. If such patients were later diagnosed with AIDS, the diagnosis date on their record (when they first met the CDC definition) would be after the report date (when CDC first received information about the patient). Such records should be excluded from certain analyses, such as survival analysis and analysis of reporting delay. CDC's AIDS surveillance data base no longer receives reports on patients who do not meet the AIDS case definition.

Follow-up of Reported AIDS Cases

AIDS case records maintained at CDC contain all information reported to date from state and local health departments. As patients progress through their illness, additional conditions may be reported, or the patient's vital status may change. However, not all health departments have the resources to routinely follow-up patients for additional information. For this reason and because many patients move out of the reporting health department's jurisdiction, CDC records do not always contain all current information for each patient.

AIDS cases reports that do not include mode of HIV exposure information are routinely followed up by state and local health departments. As of December 1999, excluding cases which were not yet investigated, mode of exposure information has been identified for 78 percent of cases. Twenty-one percent of cases were closed with incomplete information because the patient died, declined interview, or was lost to follow-up; 1 percent of cases remained without a reported risk for HIV infection after complete investigation (see Centers for Disease Control and Prevention. HIV/AIDS Surveillance Report, 1999;11 (no.2): 27). The demographic profile of persons who remain without risk information is more similar to that of other persons reported with AIDS than with the general U.S. population.

Evaluation of AIDS Surveillance

Cases of AIDS may not be reported to CDC for a variety of reasons. The diagnostic tests needed to confirm the diagnosis of certain AIDS-indicator conditions may not be performed, or physicians and hospital personnel may fail to report cases to the health department. Further, some patients with HIV disease may be ill or die from diseases or conditions not included in the current AIDS surveillance definition or from causes unrelated to their HIV infection.

Both CDC and state and local health departments have commissioned a variety of studies to evaluate the completeness of AIDS surveillance. Most evaluation projects have used alternate data resources if they are independent of routine case finding, such as death certificates, hospital discharge records, and laboratory records. Individual records from these alternate sources have then been matched against records in AIDS surveillance data bases. If an alternative source is found to be a productive source of case reports, it may be added to routine case finding methods. Evaluation projects have varied in size and scope (e.g., varying numbers of ICD-9 codes from death certificates or computerized discharge records), geographic area covered, detection of both inpatient and outpatient cases, and time frames. In general, evaluation studies suggest that reporting of AIDS cases is fairly complete; but, depending on the setting and evaluation method used, the level of reporting completeness may vary. High prevalence areas for AIDS appear to have more complete reporting than low prevalence areas. Following implementation of active case finding under the 1987 case definition, with funding support from CDC, completeness of case reporting increased in most areas and was estimated to be more than 85 percent complete (see Journal of Acquired Immunodeficiency Syndrome, 1992;5:257-64 and American Journal of Public Health 1992;82:1495-99).

Summary

Public health surveillance represents an ongoing and regular collection, analysis, interpretation, and application of health data for disease prevention and control. AIDS surveillance, like other national surveillance efforts, depends on health care providers and the state and local health departments and, thus, requires a balance between information needs versus practical limitations. AIDS surveillance in the United States represents an unprecedented public health enterprise and has achieved an unusually high degree of completeness. In addition, surveillance has changed as understanding of AIDS and HIV infection have grown. Users of the public information data set should be familiar with the characteristics of public health surveillance in general as well as with the evolution of AIDS surveillance.


Data File Variables and Coding Schemes

The rectangular data file included in the AIDS Public Information Data Set contains one line of data for each AIDS case reported to CDC. Each line contains 35 columns. The columns contain 16 variables extracted from CDC's national AIDS data set.

Each of these variables is coded alpha-numerically. The codes used in the AIDS Public Information Data Set are described below.

Age (column 1)

This variable contains the patient's age when he or she was first diagnosed with an AIDS-indicator disease.

0 = Less than 1 year old
1 = 1 to 12 years old
2 = 13 to 19 years old
3 = 20 to 24 years old
4 = 25 to 29 years old
5 = 30 to 34 years old
6 = 35 to 39 years old
      or age is missing
7 = 40 to 44 years old
8 = 45 to 49 years old
9 = 50 to 54 years old
A= 55 to 59 years old
B = 60 to 64 years old
C = 65 years old or older

Sexclass (column 2)

Adult/adolescent males are classified according to their sexual orientation.

1 = Adult/adolescent male who has sex only with other men or sex is missing,
      or sexual orientation is missing
2 = Adult/adolescent male who has sex with both men and women
3 = Adult/adolescent heterosexual male or pediatric male
4 = Female (both adult/adolescent and pediatric)

Race (column 3)

1 = White (not Hispanic)
2 = Black (not Hispanic)
3 = Hispanic
4 = Asian/Pacific Islander
5 = American Indian/Alaskan Native
9 = Unknown

Categ (column 4)

This variable reflects changes made over time to the CDC surveillance definition for AIDS. Only cases meeting the current (1993) surveillance definition are included in this data set. Categ indicates whether the patient also met the pre-1985, 1985, or 1987 surveillance definition, and whether the diagnosis, if it meets the 1987 or 1993 definition, was definitive or presumptive. Cases that meet more than one of these surveillance definitions are classified into the category listed first. For more information about the 1993 definition, see Morbidity and Mortality Weekly Report, December 18, 1992, Recommendations and Reports.

1 = Case meets the pre-1985 surveillance definition
2 = Case meets the 1985 surveillance definition
3 = Case meets the 1987 surveillance definition and was diagnosed definitively
4 = Case meets the 1987 surveillance definition and was diagnosed presumptively
5 = Case meets the 1993 surveillance definition: pulmonary tuberculosis, recurrent pneumonia,
      and/or cervical cancer (definitive diagnosis)
6 = Case meets the 1993 surveillance definition: pulmonary tuberculosis and/or recurrent
      pneumonia (presumptive diagnosis)
7 = Case meets the 1993 surveillance definition, severe HIV-related immunosuppression

Dxdate (columns 5 through 10)

This variable contains the year and month in which the first AIDS-indicator condition was diagnosed. Columns 5 through 8 contain the year; columns 9 and 10 contain the month. Cases diagnosed before 1982 are coded as “198199.” Cases whose month of diagnosis is unknown are coded as “99” in the month portion of this variable.

Repdate (columns 11 through 16)

This variable contains the year and month in which CDC received the case report. Columns 11 through 14 contain the year; columns 15 and 16 contain the month. Cases reported during 1981 are coded as “198199.”

Death (column 17)

0 = CDC has not received a death notification for this case
1 = CDC has been notified that this patient died

Patients diagnosed during the 2 most recent years are coded as “0” regardless of the patient's vital status. AIDS prevalence rates calculated for the most recent two-year period should be interpreted with caution. The rates calculated will be artificially high because all persons diagnosed in this period are coded with a vital status of “0” (alive), even if a death has been reported to CDC for that person. This is to prevent inadvertent indirect identification of any record by linking a death date inferred from this data set to other publicly available data sets which contain death dates on individuals. For more information on trends in AIDS, see Morbidity and Mortality Weekly Report, September 19, 1997 and April 24, 1998.

Exposure (columns 18 and 19)

For surveillance purposes, 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. Persons with multiple reported modes of exposure are indicated in the variable multrisk.

“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 Morbidity and Mortality Weekly Report, March 11, 1994). 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.”

“Risk not 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 reported or 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.

Adult/adolescent exposure categories

1 = Men who have sex with men
2 = Injecting drug use
3 = Men who have sex with men and inject drugs
4 = Hemophilia/coagulation disorder
5 = Heterosexual contact with a person with, or at increases risk for, HIV infection
7 = Receipt of blood transfusion, blood components, or tissue
8 = Risk not reported or identified

Pediatric exposure categories

9 = Hemophilia/coagulation disorder
10 = Mother with, or at risk for, HIV infection
11 = Receipt of blood transfusion, blood components, or tissue
12 = Risk not reported or identified

Multrisk (column 20)

Multrisk is coded only for adult/adolescent patients (13 years old or older) and indicates if the patient has risk(s) of exposure to HIV other than the one indicated by exposure.

0 = Patient's only mode of exposure to HIV is that indicated by exposure
1 = Patient has additional risk(s) of exposure
2 = Patient's mode of exposure is not reported or identified

Birth (column 21)

1 = Patient was born in the United States or its dependencies and possessions,
      or place of birth was not specified
2 = Patient was born outside the United States

Heterosexual risk information (columns 22 through 25)

These variables (sexbi, sexiv, sexother, and sexhiv) contain additional exposure information for patients infected heterosexually. All 4 variables are coded as follows:

0 = no
1 = yes
9 = missing/unknown

The variable sexbi is coded only for women (for men, the variable contains a blank). All 4 variables contain “9” (missing/unknown) for patients with hemophilia, regardless of whether the exposure information is in fact unknown. This restriction is necessary in order to comply with the Assurance of Confidentiality on page 5. Of the 4,596 AIDS cases reported through December 1995 among adults/adolescents with hemophilia, less than 4 percent also reported heterosexual contact with a person at increased risk for AIDS or HIV infection.

Adjwgt (columns 26 through 31)

This variable contains an adjustment weight which, when used as a weighting variable in a frequency tabulation, produces tabulations of AIDS cases that are adjusted for delays in case reporting (see page 11 for a discussion of delays in reporting). The weights are based on estimated reporting delay distributions that take into account exposure, geographic, and demographic variations in case reporting. The adjustment weights and the resulting tabulations are not reliable for cases diagnosed during the most recent 6 months. The Tools menu contains an adjusted weight option. If you select this option, all subsequent tabulations you request will be weighted accordingly.

MSA (columns 32 through 35)

Metropolitan area of residence at diagnosis of AIDS is identified for adult/adolescent patients residing in MSAs with 500,000 or more population, according to the latest available official U.S. Bureau of Census estimates. Each MSA is identified by a 4-digit code listed in Appendix B. For adult/adolescent patients residing in an MSA with less than 500,000 population, in a non-metropolitan area, or whose metropolitan area of residence is unknown, and for all pediatric patients, region of residence is identified. The regional codes are:

1 = Northeast: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey,
      New York, Pennsylvania, Rhode Island, and Vermont
2 = Midwest: Indiana, Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska,
      North Dakota, Ohio, South Dakota, and Wisconsin
3 = South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia,
      Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South
      Carolina, Tennessee, Texas, Virginia, and West Virginia
4 = West: Alaska, Arizona, California, Colorado, Idaho, Hawaii, Montana, Nevada, New
      Mexico, Oregon, Utah, Washington, and Wyoming
5 = U.S. dependencies, possessions, and independent nations in free association
      with the United States: Guam, Puerto Rico, the U.S. Virgin Islands, and the U.S.
      Pacific Islands listed on page 8.

State, MSA, and County Tables

In addition to the rectangular data file discussed in section 2, the AIDS Public Information Data Set contains tabular data by state, metropolitan area, and county or health district. These tables consist of frequency tables and 2-way cross tabulations of 8 variables extracted from CDC's national AIDS surveillance data set. For counties or health districts, the data set contains only 1-way tables of 3 variables age, race/ethnicity, and sex). The data set contains one set of tables for the entire United States, one set for each state and for the District of Columbia, one set for each MSA, and one set for each county or health district. All MSAs with 500,00 or more population are included in the data set. Selected MSAs with populations between 100,000 and 500,000, and selected counties or health districts are included in the data set, based on the data release policies of the individual states.

Data from MSAs with populations between 100,000 and 500,000 are included from Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia, and Wyoming.

Data from individual counties are included from Arkansas, Delaware, Georgia, Hawaii, Indiana, Louisiana, Minnesota, Missouri, Nevada, New Hampshire, New Jersey, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, and Washington.

Data from health districts are included from Florida, Idaho, Kentucky, Mississippi, Montana, Nebraska, New Mexico, South Carolina, Tennessee, Virginia, and West Virginia.

See Appendix B for a list of MSAs. See Appendix C for a list of counties which comprise each health district.

The variables included in the state and MSA tables are:

For counties and health districts, 1-way tables are available for the variables age, race/ethnicity, and sex. The values used for the variables are printed below.

Age

This variable contains the patient's age when he or she was first diagnosed with an AIDS-indicator condition. Ages printed in the documentation file are grouped as follows:

0 - 1
1 - 12
13 - 19
20 - 29
30 - 39
40 - 49
50 - 59
60 +

Categ

This variable reflects revisions made to the CDC surveillance definition for AIDS. Only cases meeting the current (1993) surveillance definition are included in the data set. Categ indicates whether the patient also meets the pre-1985, 1985, or 1987 surveillance definition, and whether the diagnosis, if it meets the 1987 or 1993 definition, was definitive or presumptive. Cases that meet more than one of these surveillance definitions are classified into the definition category listed first. For more information about the 1993 definition, see Morbidity and Mortality Weekly Report, Recommendations and Reports, December 18, 1992.

1 = Case meets the pre-1985 surveillance definition
2 = Case meets the 1985 surveillance definition
3 = Case meets the 1987 surveillance definition and was diagnosed definitively
4 = Case meets the 1987 surveillance definition and was diagnosed presumptively
5 = Case meets the 1993 surveillance definition: pulmonary tuberculosis,
      recurrent pneumonia, and/or cervical cancer (definitive diagnosis)
6 = Case meets the 1993 surveillance definition: pulmonary tuberculosis and/or
      recurrent pneumonia (presumptive diagnosis)
7 = Cases meets the 1993 surveillance definition: severe HIV-related immunosuppression

Dth_hyr

For patients whose death has been reported to CDC, this variable contains the half-year of death. The first four numbers indicate the year; the last two indicate the first or second half of that year. For example, the value “198802" indicates that the patient died in the second half of 1988. Patients whose death has been reported to CDC, but whose date of death is unknown are coded as “999999".

Dx_hyr

This variable contains the half-year in which the first AIDS-indicator condition was diagnosed. The first four numbers indicate the year; the last two indicate the first or second half of that year.

Ent_hyr

This variable contains the half-year in which CDC received the case report. The first four numbers indicate the year; the last two indicate the first or second half of that year.

Exposure

For surveillance purposes, 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 Morbidity and Mortality Weekly Report, March 11, 1994). 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.”

“Risk not 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 reported or 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.

01 = Men who have sex with men
02 = Injecting drug use
03 = Men who have sex with men and inject drugs
04 = Adult/adolescent hemophilia/coagulation disorder
05 = Heterosexual contact with a person with, or at increased risk for, HIV infection
07 = Adult/adolescent receipt of blood transfusion, blood components, or tissue
08 = Adult/adolescent risk not reported or identified
09 = Pediatric hemophilia/coagulation disorder
10 = Mother with, or at risk for, HIV infection
11 = Pediatric receipt of blood transfusion, blood components, or tissue
12 = Pediatric risk not reported or identified

Race/ethnicity

1 = White (not Hispanic)
2 = Black (not Hispanic)
3 = Hispanic
4 = Asian/Pacific Islander
5 = American Indian/Alaskan Native
9 = Unknown

Sex

1 = Male
2 = Female

Small Cell Restriction

In accordance with CDC guidelines on protecting confidentiality and with an agreement made with state and local health departments for release of these data, entries whose value is 3 or less are not included in the tables. In addition, the AIDS Public Information Data Set software allows you to combine data from more than one state, MSA, or county/health district in either separate or aggregate form. If you select the aggregate option, each count may be off by an amount equal to 3 times the number of states/MSAs/counties aggregated. For example, if you select data from California, Washington State, and Oregon, each count may be off by as many as 9 cases (3 times the number of states, in this case 3).

Appendix A: Installation

In 1997, The AIDS Public Information Data Set was rewritten to be fully Windows compatible. While much of the original program design remained unchanged, many features were added, cursor and mouse controls were enhanced, and the installation procedure changed to reflect Windows conventions. Changes to the software are more fully described in the on-line help screens. The December 2001 edition contains the changes made in 1997. As with previous releases, the software allows you to display simple statistics without additional software such SAS, SPSS, BMDP, or PRODAS. More complex analyses, however, require statistical software.

To transfer the data to another software package for analysis, you may wish to download only the ASCII version. You may also load the software and use the export option (under File) to extract the records and variables you wish to analyze. The export option will create an ASCII data file, which can then be processed by other software.
 

Loading the Software

The AIDS Public Information Data Set is available on CD, as part of the CDC HIV/AIDS Information Guide, or can be downloaded from CDC’s web site. Installation instructions vary, depending on the medium you are using.

Minimum requirements for installation are:

*   Windows 95 or greater
*   80486 CPU
*   420 K of free RAM
*   50Mb of free disk space

To install the software from CDC’s web site

1) Download the self-extracting file (APIDS01.EXE) to desired directory (i.e., C:\AIDSPIDS).

2) Click on Start and Run. Using the Browse feature, locate and run APIDS01.EXE.

You may change the drive and directory to which the AIDS Public Information Data Set will be extracted.

If you want to be able to run the program from the Start Menu, be sure "Create program group(s): AIDS Public Information Data Set" is checked.

3) Click on Extract.

4) After the program has been extracted, double click on the AIDS Public Information Data Set icon to run it. The first time you run it, it will perform a setup/indexing process that will take up to a few minutes to complete.

5) In order to save disk space, the file APIDS01.EXE can be deleted.

To load the software from the CD, insert the disk into the reader. The software will automatically display the initial screen for the CDC HIV/AIDS Information Guide. To access the AIDS Public Information Data Set, first select menu item 7, “Software.” Then select AIDS Public Information Data Set. Finally, select “Download APIDS01.EXE”.  This selection will initiate the software installation procedure described above. Simply proceed with steps 1 through 5, above.

Getting Help

The AIDS Public Information Data Set uses standard Windows interfaces, and can be mastered with minimum effort. On-line help screens describe how to use the program to display information. You can access help by pressing the <F1> key, by clicking the right (secondary) mouse button, or by selecting the Help menu. The information displayed will vary depending upon the last option you accessed. If you need additional information, contact the Statistics and Data Management Branch, Division of HIV/AIDS Prevention, telephone (404) 639-2020.

Displaying the Menus

Once you complete the installation procedure and run the program, you will see a screen with four options displayed on the upper-left corner: File, Tools, Window, and Help. Select File to display data from either the main data file or from the state, MSA, or county tables. A second screen will display so that you may select the variables you wish to tabulate. Select Tools to create indexes or set various options that control the display of data. Select Window to scroll through the tables you have created. Select Help to see further information on how to use this program.

Cursor Control

Cursor control uses a standard Windows interface. Select variables by double-clicking the left (primary) mouse button or the Enter key. An asterisk will display next to the fields you have selected. Menus and other options can also be selected by pressing the <Alt> key and typing the highlighted letter of that option.

Appendix B: Metropolitan Statistical Areas

Definitions for MSAs are issued by the Office of Management and Budget (OMB) to be used in presentation of statistics by agencies of the federal government. The metropolitan areas used on the AIDS Public Information Data Set are the MSAs for all areas except the 6 New England states. For these states, the New England County Metropolitan Areas (NECMA, also defined by OMB) are used. Metropolitan areas are named for a central city in the MSA or NECMA and may include several counties and cross state boundaries.

The AIDS Public Information Data Set contains data from all MSAs with 500,000 or more population, and from MSAs with 100,000 to 500,000 population from Arkansas, Colorado, Connecticut, Deleware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia, and Wyoming.

Code Metropolitan areas with 500,000 or more population

80        Akron, Ohio
160      Albany-Schenectady, N.Y.
200      Albuquerque, N.Mex.
240      Allentown, Pa.
440      Ann Arbor, Mich.
520      Atlanta, Ga.
640      Austin, Tex.
680      Bakersfield, Calif.
720      Baltimore, Md.
760      Baton Rouge, La.
875      Bergen-Passaic, N.J.
1000    Birmingham, Ala.
1123    Boston, Mass.
1280    Buffalo, N.Y.
1520    Charlotte, N.C.
1600    Chicago, Ill.
1640    Cincinnati, Ohio
1680    Cleveland, Ohio
1720    Colorado Springs, Colo.
1840    Columbus, Ohio
1920    Dallas, Tex.
2000    Dayton, Ohio
2020    Daytona Beach, Fla.

Code Metropolitan areas with 500,000 or more population

2080    Denver, Colo.
2160    Detroit, Mich.
2320    El Paso, Tex.
2680    Fort Lauderdale, Fla.
2760    Fort Wayne, Ind.
2800    Fort Worth, Tex.
2840    Fresno, Calif.
2960    Gary, Ind.
3000    Grand Rapids, Mich.
3120    Greensboro, N.C.
3160    Greenville, S.C.
3240    Harrisburg, Pa.
3283    Hartford, Conn.
3320    Honolulu, Hawaii
3360    Houston, Tex.
3480    Indianapolis, Ind.
3600    Jacksonville, Fla.
3640    Jersey City, N.J.
3760    Kansas City, Mo.
3840    Knoxville, Tenn.
4120    Las Vegas, Nev.
4400    Little Rock, Ark.
4480    Los Angeles, Calif.
4520    Louisville, Ky.
4880    McAllen, Tex.
4920    Memphis, Tenn.
5000    Miami, Fla.
5015    Middlesex, N.J.
5080    Milwaukee, Wis.
5120    Minneapolis-Saint Paul, Minn.
5160    Mobile, Ala.
5190    Monmouth-Ocean City, N.J.
5360    Nashville, Tenn.
5380    Nassau-Suffolk, N.Y.
5483    New Haven, Conn.
5560    New Orleans, La.
5600    New York, N.Y.
5640    Newark, N.J.
5720    Norfolk, Va.
5775    Oakland, Calif.
5880    Oklahoma City, Okla.

Code Metropolitan areas with 500,000 or more population

5920    Omaha, Nebr.
5945    Orange County, Calif.
5960    Orlando, Fla.
6160    Philadelphia, Pa.
6200    Phoenix, Ariz.
6280    Pittsburgh, Pa.
6440    Portland, Oreg.
6483    Providence, R.I.
6640    Raleigh-Durham, N.C.
6760    Richmond, Va.
6780    Riverside-San Bernardino, Calif.
6840    Rochester, N.Y.
6920    Sacramento, Calif.
7040    Saint Louis, Mo.
7160    Salt Lake City, Utah
7240    San Antonio, Tex.
7320    San Diego, Calif.
7360    San Francisco, Calif.
7400    San Jose, Calif.
7440    San Juan, P.R.
7510    Sarasota, Fla.
7560    Scranton, Pa.
7600    Seattle, Wash.
8003    Springfield, Mass.
8120    Stockton, Calif.
8160    Syracuse, N.Y.
8200    Tacoma, Wash.
8280    Tampa-Saint Petersburg, Fla.
8400    Toledo, Ohio
8520    Tucson, Ariz.
8560    Tulsa, Okla.
8735    Ventura, Calif.
8840    Washington, D.C.
8960    West Palm Beach, Fla.
9040    Wichita, Kans.
9160    Wilmington, Del.
9243    Worcester, Mass.
9320    Youngstown, Ohio

Code Metropolitan areas with 100,000 to 500,000 population

40        Abilene, Tex.
120      Albany, Ga.
220      Alexandria, La.
280      Altoona, Pa.
320      Amarillo, Tex.
480      Asheville, N.C.
500      Athens, Ga.
560      Atlantic-Cape May, N.J.
600      Augusta, Ga.
733      Bangor, Maine
840      Beaumont, Tex.
860      Bellingham, Wash.
870      Benton Harbor, Mich
880      Billings, Mont.
920      Biloxi, Miss.
1020    Bloomington, Ind.
1040    Bloomington, Ill.
1080    Boise, Idaho
1125    Boulder, Colo.
1145    Brazoria, Tex.
1150    Bremerton, Wash.
1240    Brownsville, Tex.
1260    Bryan, Tex.
1320    Canton, Ohio
1360    Cedar Rapids, Iowa
1400    Champaign-Urbana, Ill.
1440    Charleston, S.C.
1480    Charleston, W.Va.
1540    Charlottesville, Va.
1560    Chattanooga, Tenn.
1660    Clarksville, Tenn.
1740    Columbia, Mo.
1760    Columbia, S.C.
1800    Columbus, Ga.
1880    Corpus Christi, Tex.
1900    Cumberland, Md.
1950    Danville, Va.
1960    Davenport, Iowa
2040    Decatur, Ill.
2120    Des Moine, Iowa
2190    Dover, Del.

Code Metropolitan areas with 100,000 to 500,000 population

2240    Duluth, Minn.
2330    Elkhart, Ind.
2360    Erie, Penn.
2400    Eugene, Oreg.
2440    Evansville, Ind.
2520    Fargo, N.D.
2560    Fayetteville, N.C.
2580    Fayetteville, Ark.
2640    Flint, Mich.
2655    Florence, S.C.
2670    Fort Collins, Colo.
2700    Fort Myers, Fla.
2710    Fort Pierce, Fla.
2720    Fort Smith, Ark.
2750    Fort Walton Beach, Fla.
2900    Gainesville, Fla.
2920    Galveston, Tex.
2980    Goldsboro, N.C.
2995    Grand Junction, Colo.
3060    Greeley, Colo.
3150    Greenville, N.C.
3180    Hagerstown, Md.
3200    Hamilton, Ohio
3285    Hattiesburg, Miss.
3290    Hickory, N.C.
3350    Houma, La.
3400    Huntington, W.Va.
3500    Iowa City, Iowa
3520    Jackson, Mich.
3560    Jackson, Miss.
3580    Jackson, Tenn.
3605    Jacksonville, N.C.
3660    Johnson City, Tenn.
3680    Johnstown, Pa.
3710    Joplin, Mo.
3720    Kalamazoo, Mich.
3740    Kankakee, Ill.
3810    Killeen, Tex.
3850    Kokomo, Ind.
3880    Lafayette, La.

Code Metropolitan areas with 100,000 to 500,000 population

3920    Lafayette, Ind.
3960    Lake Charles, La.
3980    Lakeland, Fla.
4000    Lancaster, Pa.
4040    Lansing, Mich.
4080    Laredo, Tex.
4100    Las Cruces, N.Mex.
4200    Lawton, Okla.
4243    Lewiston, Maine
4280    Lexington, Ky.
4320    Lima, Ohio
4360    Lincoln, Nebr.
4420    Longview, Tex.
4600    Lubbock, Tex.
4640    Lynchburg, Va.
4680    Macon, Ga.
4800    Mansfield, Ohio
4890    Medford, Oreg.
4900    Melbourne, Fla.
5200    Monroe, La.
5280    Muncie, Ind.
5330    Myrtle Beach, S.C.
5345    Naples, Fla.
5523    New London, Conn.
5660    Newburgh, N.Y.
5790    Ocala, Fla.
5800    Odessa, Tex.
5910    Olympia, Wash.
6015    Panama City, Fla.
6020    Parkersburg, W.Va.
6080    Pensacola, Fla.
6120    Peoria, Ill.
6403    Portland, Maine
6560    Pueblo, Colo.
6580    Punta Gorda, Fla.
6680    Reading, Pa.
6720    Reno, Nev.
6740    Richland, Wash.
6800    Roanoke, Va.
6820    Rochester, Minn.

Code Metropolitan areas with 100,000 to 500,000 population

6880    Rockford, Ill.
6895    Rocky Mount, N.C.
6960    Saginaw, Mich.
6980    Saint Cloud, Minn.
7080    Salem, Oreg.
7200    San Angelo, Tex.
7490    Santa Fe, N.Mex.
7520    Savannah, Ga.
7610    Sharon, Pa.
7640    Sherman, Tex.
7680    Shreveport, La.
7720    Sioux City, Iowa
7800    South Bend, Ind.
7840    Spokane, Wash.
7880    Springfield, Ill.
7920    Springfield, Mo.
8050    State College, Pa.
8080    Steubenville, Ohio
8140    Sumter, S.C.
8240    Tallahassee, Fla.
8320    Terre Haute, Ind.
8360    Texarkana, Tex.
8440    Topeka, Kans.
8480    Trenton, N.J.
8640    Tyler, Tex.
8720    Vallejo, Calif.
8760    Vineland, N.J.
8800    Waco, Tex.
8920    Waterloo, Iowa
9000    Wheeling, W.Va.
9080    Wichita Falls, Tex.
9140    Williamsport, Pa.
9200    Wilmington, N.C.
9260    Yakima, Wash.
9280    York, Pa.

Appendix C: Health Districts