Purpose Of The Database And Study Design: ASD is a national surveillance project that collects demographic, clinical, behavioral, laboratory, health care use, and other related data on HIV positive individuals 13 years of age and older. ASD provides a method for monitoring the full spectrum of HIV-related illnesses and evaluating trends in those illnesses. Although advances in HIV/AIDS therapy are reducing the number of HIV positive persons advancing to AIDS, many non-AIDS-defining illnesses (e.g., pneumonia) continue to occur. ASD defines the spectrum and magnitude of those non-AIDS-defining illnesses, as well as AIDS-related illnesses.
Nature Of The Data Collected: Longitudinal medical record reviews conducted to study a natural cohort of HIV positive adults
Unit Of Analysis: Individual patients treated at hospital-based outpatient clinics and community-based clinical practices.
Data Collection Methods: ASD uses an observational cohort study design and is conducted through cooperative agreements with health departments in Los Angeles, New York City, Atlanta, Detroit, Denver, Houston, San Antonio, New Orleans, Seattle, and Puerto Rico. Cases are drawn from hospital inpatient and outpatient facilities, infectious disease practitioners specializing in HIV infection, private practice medical groups, HIV treatment facilities, and HMOs. About two-thirds of the cohort receive care in public facilities. ASD follows HIV/AIDS patients accessing care at participating sites to retrieve clinical, treatment, and laboratory data from medical records at six-month intervals, beginning with the entry of the patient into the ASD database and ending with the patient’s death or loss to follow-up. ASD provides risk information and provides surveillance of HIV-related illnesses. ASD data are recorded using standardized software. Information is sent to CDC without personal identifiers. Data analysis is performed at participating State and local health departments and at the CDC.
General Attributes: From the inception of ASD in 1990 to June 1999, over 47,000 patients diagnosed with HIV or AIDS have been observed.
Major Data Constructs And Key Data Elements: Demographic characteristics; mode of HIV exposure; AIDS-defining conditions; other clinical conditions, diagnostic, immunologic, and virologic test results; treatment and prophylaxis; hospitalization dates and discharge diagnoses; date and cause of death; and social data.
Strengths And Weaknesses Of The Study Design And Database: Since its inception, ASD has been the primary source of information for monitoring OIs; served as a sentinel surveillance system for new OIs; provided the data necessary to revise the AIDS case definition in 1993; provided the data necessary to develop the “smearing forward” method of evaluating immunologically-diagnosed AIDS cases over time; and contributed to CDC’s ability to statistically adjust incident AIDS diagnoses to account for the change in the AIDS case definition. The number of records and the diversity of the patient population contained in the database has made ASD data the primary source of information for current PHS HIV treatment guidelines by demonstrating the impact of various treatment regimens on changing patterns of morbidity in the HIV positive population. ASD data represent a diverse group of HIV positive individuals. The database, however, is facility-based and does not represent the HIV positive population in the US.
Gaps In The Data Collected And Factors Leading To The Gaps: CDC is now piloting an ASD-related, population-based surveillance project to monitor preventable OIs and access to care and treatment.
Feasibility Of Linking With Other Databases: Linkage is feasible at the local level.
Process To Access The Database And Contact Person: For more information contact: Chief, Surveillance Branch, Division of HIV/AIDS Prevention, Surveillance, and Epidemiology, CDC, Mailstop E-47, 1600 Clifton Road, NE, Atlanta GA 30333; (404) 639-2050.
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