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National HIV Surveillance System (NHSS)

Description

The HIV Surveillance System is the nation's source of timely information used to track the HIV/AIDS epidemic. [The term HIV/AIDS is used to refer to 3 categories of diagnoses collectively: (1) a diagnosis of HIV infection (not AIDS), (2) a diagnosis of HIV infection and a later diagnosis of AIDS, and (3) concurrent diagnoses of HIV infection and AIDS.] HIV/AIDS surveillance is conducted by health departments in each state or territory and the District of Columbia. Data are collected using standard confidential case reports and are reported to CDC without personal identifiers.

Supplier

Centers for Disease Control and Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (CDC/NCHHSTP)

Data Years Available

1981-present

Periodicity

Annual

Mode

State and Territorial Health Departments report HIV/AIDS cases to CDC using uniform surveillance case definitions and case report form.

Selected Content

Data include demographic characteristics, living status, mode of exposure to HIV, case definition category, and other clinical information.

Population covered

All 50 states, the District of Columbia, U.S., dependencies and possessions, and independent nations in free association with the United States report HIV/AIDS data to CDC.

Methodology

The HIV/AIDS surveillance activities employed by most reporting areas include four major reporting sources: hospitals, physicians, public and private clinics, and medical records systems (death certificates, tumor registries, etc.). Using a standard confidential case report, the health departments collect information and transmit it to CDC electronically, without personal identifiers. Estimated data on HIV infection and AIDS are adjusted using a maximum likelihood statistical procedure that accounts for the differences in reporting delays among various characteristics (demographic, vital status, etc.). HIV/AIDS surveillance data are provisional and are updated annually.

Response rate and sample size

Although completeness of reporting differs by geographic region and patient population, studies conducted by state and local health departments indicate that the reporting of AIDS cases in most areas is more than 85 %complete.

Interpretation Issues

The case definitions of HIV infection and AIDS have been modified several times since 1985. To assess trends in AIDS cases, deaths, and prevalence, it is preferable to use case definitions adjusted for reporting delays and presented by year of diagnosis, rather than counts by year of report.

References

National Center for Health Statistics. Health United States 2009: With Special Feature on Medical Technology. Hyattsville, Maryland. 2010; pp 446-447. http://www.cdc.gov/hiv/topics/surveillance