Validating population surveys for the measurement of HIV/STD prevention indicators

Objective: To validate the World Health Organization/Global Programme on AIDS (GPA) protocol for measuring HIV/sexually transmitted disease prevention indicators pertaining to knowledge and sexual practices of the general population. Methods: Data were collected in Uganda during 1993. Three different interview strategies were complemented with qualitative methods, including observations at visits and key-informant interviews. Two interview strategies consisted of structured questionnaires which were applied to 460 randomly selected people aged 15-49 years and 60 intentionally selected women who were known prostitutes. The third strategy involved in-depth interviewing and was applied to a random subset of all respondents (n = 75). Results: The three interview strategies generated similar results for demographic characteristics. The strategies using structured questionnaires gave similar results with regards to the number of reported sex partners and the prevalence of condom use, but differed from in-depth interviews on these aspects. The high numbers of casual sex partners of female prostitutes was confirmed by in-depth interviews but not via the questionnaires. Conclusion: The CPA questionnaire may not be optimal to capture people at high risk and to assess sexual behaviour, especially of people at high risk. Nevertheless, the questionnaire provides the most realistic option, since in-depth interviews are expensive and not as objective in assessing trends over time. Evaluation studies of HIV interventions in the general population should therefore be complemented with small qualitative studies to detect and iron out biases in interpreting results.