November 30, 2012
* Transmission category is the term used to summarize a person's HIV risk factors; the summary classification results from selecting, from the presumed hierarchical order of probability, the one risk factor most likely to have been responsible for transmission. For surveillance purposes, a single transmission category is assigned to each diagnosis of HIV infection. Persons with more than one reported risk factor for HIV infection are classified in the transmission category listed first in a hierarchy of transmission categories based on their presumed order of probability. An exception is the category for male-to-male sexual contact and injection drug use; this group makes up a separate transmission category. Persons whose transmission category is classified as male-to-male sexual contact include males who ever had sexual contact with other males and males who ever had sexual contact with both males and females.
† Through HIV incidence surveillance, data on HIV testing and antiretroviral use history are used to calculate the probability that a person would have a test for HIV infection during a defined recency period, and these probabilities are used to assign a weight to each new diagnosis classified as a recent infection, using results of the serologic testing algorithm for recent HIV seroconversion. Weights are summed to determine the incidence of HIV infection in the 18 states and two cities that provide HIV incidence surveillance data. To extrapolate results to the entire United States, the ratio of the number of new HIV infections to the number of new HIV diagnoses in the areas providing data is applied to the number of new HIV diagnoses in the areas that did not contribute data.
§ The national YRBS used a three-stage cluster sample to obtain cross-sectional data representative of public and private school students in grades 9-12 in the 50 states and District of Columbia. The school response rate was 81%, the student response rate was 87%, and the overall response rate was 71%.
¶ These surveys used a two-stage cluster sample to obtain additional data representative of public school students in grade 9-12 in 11 states (Connecticut, Delaware, Florida, Hawaii, Illinois, Massachusetts, Michigan, New Hampshire, Rhode Island, Vermont, and Wisconsin) and nine large urban school districts (Boston, Chicago, Detroit, District of Columbia, Los Angeles, Milwaukee, New York City, San Diego, and Seattle) and public and private school students in grades 9-12 in one state (Ohio). The school response rates averaged 92%, the student response rates averaged 80%, and the overall response rates averaged 73%.
** NHIS is a nationally representative, annual, cross-sectional, multistage probability sample household survey that provides prevalence estimates for a broad range of health measures for the civilian, noninstitutionalized U.S. population, based on in-person interviews with a nationally representative sample of adults aged ≥18 years. This report presents NHIS data for adults aged 18-24 years living in the 50 states and District of Columbia. The final response rate for the adult sample person component was calculated as 60.8%.
¶¶ Additional information available at www.cdc.gov/hiv/topics/research/prs/subset-best-evidence-interventions.htm#link2.3.
*** Additional information available at http://whqlibdoc.who.int/publications/2009/9789241598859_eng.pdf.
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