Sexual risk behaviour and infection: epidemiological considerations.

R esearchers into sexually transmitted disease (STD) have been trying to measure sexual behaviour for a very long time. Following the emergence of the HIV pandemic in the 1980s and 1990s, the focus on sexual measurement intensified. Researchers attempted to measure sexual behaviour in a wide variety of contexts for various purposes, often without explicit attention to the impact of context and purpose on measurement. Investigators measured sexual behaviour in STD and family planning clinics to assess clients’ risk for sexually transmitted infection (STI): in infected and uninfected populations to identify behavioural risk factors for STI; in specific groups to describe and identify high and low risk subpopulations; in general populations to describe behaviour patterns and monitor changing trends through time, and finally in intervention trials and intervention programmes to assess efficacy and effectiveness of behavioural interventions. Often the same sexual behaviour questions were used for different purposes and in the variety of contexts mentioned above. The accumulating experience in sexual behaviour measurement, as it relates to STDs, suggests that the ‘‘one size fits all’’ approach may be inadequate for the diverse purposes at hand. A careful analysis of what needs to be measured for different purposes, in different contexts, may be needed to help move the sexual behaviour measurement field forward. This paper describes the measurement of sexual behaviour in the context of STI transmission. It reviews studies undertaken (1) to monitor sexual behaviour and (2) to assess the role of specific sexual behaviours in the transmission of specific STIs. Issues discussed include: