[An index of HIV infection risk in the population]

The paper presents a risk index constructed on the basis of some sexual behaviour-related variables. It is intended for measuring the risk of exposure to HIV infection for the general population. Variables are from a study on Lifestyle and Health conducted on a sample of the population living in the London, Edinburgh, and Glasgow metropolitan area by the Research Unit in Health and Behavioural Change at the Edinburgh University. The construction of the index has been realized through a delphi study which has collected information from a panel of AIDS national experts. Methodological problems in summarising information coming from several variables are discussed. The main task of the study is not to provide a total prediction of HIV infection in the population of Britain, but to assess the component which may stem from sexual behaviours when estimated from self-reports. Major findings are the consistency of the population in the "medium risk" group, that, if a spread of AIDS among the heterosexual population can be hypothesized, gives a rather pessimist scenario. Moreover, a trend analysis (possible because of the continuity in the data collection) shows an increase in this "medium risk" group, although the "high risk" group appears much less consistent (less than two percent) and slowly declining over time.