Purpose Of The Database And Study Design: MACS is a study of HIV infection in homosexual and bisexual men. Selected participants currently being followed include: HIV positive men who were enrolled in the study as seroprevalent cases or who have seroconverted while in the study; HIV-seronegative men at high risk of HIV-infection based on behavioral assessments, and a matched set of seronegative men who are at lower risk of HIV infection. NIAID plans to follow these subjects through at least 2005. MACS data have been used to conduct an array of HIV research including: clinical effects of therapy, trends in survival, and trends in HIV-related clinical events; correlation of host immune responses to the development of HIV disease; use of viral load as a predictor of outcome following seroconversion; use of viral factors including HIV phenotyping to determine disease outcome; trends in health service use; and HIV-related neuropsychological outcomes.
Nature Of The Data Collected: Longitudinal collection of clinical specimens and interview data
Unit Of Analysis: A matched cohort of HIV positive and seronegative men
Data Collection Methods: MACS subjects are followed at the clinical centers at six-month intervals. During their visits, they respond to a detailed health questionnaire, receive a physical examination, and have blood specimens taken. These specimens are processed and stored as frozen serum, plasma, and cells in the NIAID AIDS Specimen Repository. Additional samples of blood and other body fluids and tissues are collected for specific MACS pathogenesis protocols.
General Attributes: Over 5,500 men have participated in the MACS since the initial enrollment in 1984. MACS clinical centers include Baltimore, Pittsburgh, Chicago, and Los Angeles. Over one million specimens are housed in the NIAID AIDS Specimen Repository.
Major Data Constructs And Key Data Elements: Data collected include: immunologic, virologic, and other biologic determinants of disease progression, factors that are associated with HIV-mediated immune system destruction; and factors that might protect individuals from becoming HIV positive. Interview data include detailed questions regarding: sexual practices, HIV-related symptoms, use of health services, demographic and psychosocial characteristics, and quality of life.
Strengths And Weaknesses Of The Study Design And Database: MACS has experienced a high retention rate, with loss to follow-up of less than 20 percent among HIV positive men after ten years. MACS represents a repository of clinical specimens that cover the natural history of HIV infection and disease among a large cohort of at-risk individuals. The cohort has a disproportionately low number of minority homosexual and bisexual men participating. The MACS cohort also is not generalizable to segments of the newly HIV positive population who tend to have become HIV positive through injecting drug use or heterosexual transmission. The MACS cohort also is not generalizable to HIV positive women, a rapidly growing segment of the HIV positive population.
Gaps In The Data Collected And Factors Leading To The Gaps: None identified
Feasibility Of Linking With Other Databases: Feasibility is unclear. Public use tapes of accumulated MACS data are created biannually.
Process To Access The Database And Contact Person: Public use tapes may be obtained from NTIS. To order call (800) 553-6847 or through the NIAID website: http://www.niaid.nih.gov/research/aidsdata.htm.
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