Behavioural data collection: Analysis and interpretation issues Public Health Conference, 15 May 2006 Gauteng Department of Health, the University of the Witwatersrand School of Public Health, the International Epidemiological Association and the Health Systems Trust Warren Parker PhD Centre for AIDS Development, Research and Evaluation

What surveys tell us (1) HIV infection is largely determined by sexual transmission and survey measures have been developed to inform indicators of sexual behaviour Main demographic data include age, sex, race, marital status, employment, geotype and province Behavioural measures include - ever had sex - sex in past 12 months - age of recent sexual partner - condom use Other related measures include knowledge, stigma measures, communication exposure, VCT

What surveys tell us (2) Analysis of behavioural data provides descriptive overview of levels of sexual activity and preventive practices Correlations can also be made with HIV prevalence, and more recently, HIV incidence Findings often raise questions, challenge assumptions, and suggest new areas of analysis and research

HIV: Sex and age distribution

HIV: Provincial distribution

HIV: Geotype distribution

Sexual experience

Age at first sex

Reasons for no sexual debut

Sexual frequency by age

Sexual partnerships

Age difference and HIV status

Condom use

What’s missing? Surveys provide descriptive overview sexual behaviour and correlates with HIV ‘Surveillance’ of sexual behaviour is problematic, because limited detail can be obtained through a questionnaire, and privacy/honesty/reticence are issues (evidenced by HIV+ status amongst reported non-sexually actives, etc.) HIV prevalence is a problematic measure as it doesn’t allow for correlation between current sexual practices and HIV incidence (which may have occurred many years previously)

Explanations and hypotheses HIV prevalence and behavioural surveys provide overview and insight into understanding of ‘what’ but insufficient insight into ‘why’.

Exercise Why is HIV amongst youth <20 so high, when reported sexual debut, sexual frequency, partner numbers are low, and condom use at last sex is high? Why does HIV prevalence vary markedly by province? Why is HIV prevalence markedly higher in informal urban areas? What do we need to understand about sexual behaviour to clearly understand HIV risk? Why have high levels of condom use not impacted on HIV prevalence?