Generalizability of population-based studies on AIDS: a comparison of newly and continuously surveyed villages in rural southwest Uganda

BACKGROUND: Population-based studies are thought to provide generalizable epidemiological data on the human immunodeficiency virus type 1 (HIV-1) epidemic. However, longitudinal studies are susceptible to bias from added attention caused by study activities. We compare HIV-1 prevalence in previously and newly surveyed villages in rural southwest Uganda. METHODS: The study population resided in 25 neighbouring villages, of which 15 have been surveyed for 10 years. Respondents (>/=13 years) provided socio-demographic and sexual behaviour data and a blood sample for HIV-1 serology in private after informed consent. We tested the independent effect of residency: (1) original versus new villages; (2) proximity to main road; and (3) proximity to trading centre on HIV-1 serostatus of respondents using multivariate logistic regression. RESULTS: There were 8,990 adults censused, 68.3% were from the original villages, 48.2% were males and 6111 (68.0%) were interviewed and had definite HIV-1 serostatus. The HIV-1 prevalence was 6.1% overall, 5.7% in the new, and 6.4% in the original villages (P = 0.25). Residency in the new or original villages did not independently predict HIV-1 serostatus of respondents (P = 0.46). Independent predictors of HIV-1 serostatus were education (primary or higher, odds ratio OR = 1.7 and 1.4, respectively), being separated or widowed OR = 4.2, reported previous use of a condom OR = 1.8, or reported genital ulceration OR = 3.3, and age group 25-34 and 35-44 years OR = 5.8 and OR = 4.8 (all P </= 0.001). CONCLUSIONS: In the context of rural Uganda where there has been considerable health education about AIDS, the additional attention to HIV infection caused by this longitudinal study does not appear to have appreciably affected the prevalence of HIV-1 infection.