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Antenatal clinic HIV data found to underestimate actual prevalence declines: evidence from Zambia

2008; Wiley; Volume: 13; Issue: 2 Linguagem: Inglês

10.1111/j.1365-3156.2007.01987.x

1365-3156

Charles Michelo, Ingvild Fossgard Sandøy, Knut Fýlkesnes,

Food Security and Health in Diverse Populations

Summary Objective To determine to what extent antenatal clinic (ANC)‐based estimates reflect HIV prevalence trends among men and women in a high prevalence urban population. Methods Examination of data from serial population‐based HIV surveys in 1995 ( n = 2115), 1999 ( n = 1962) and 2003 ( n = 2692), and ANC‐based surveillance in 1994 ( n = 450), 1998 ( n = 810) and 2002 ( n = 786) in the same site in Lusaka, Zambia. The population‐based surveys recorded refusal rates between 6% and 10% during the three rounds. Results Among ANC attendees, prevalence declined by 20% (25.0% to 19.9%; P = 0.101) in the age group 15–24 years and was stable overall. In the general population, the prevalence declined by 49% ( P < 0.001) and by 32% ( P < 0.001) in age group 15–24 and 15–49, respectively. Among women only, HIV prevalence declined by 44% (22.5% to 12.5%; P < 0.001) and by 27% (29.6% to 21.7%; P < 0.001) in age group 15–24 and 15–49 years, respectively. In addition, prevalence substantially declined in higher educated women aged 15–24 years (20.7% to 8.5%, P < 0.001). Conclusion ANC‐based estimates substantially underestimated declines in HIV prevalence in the general population. This seemed to be partially explained by a combination of marked differentials in prevalence change by educational attainment and changes in fertility‐related behaviours among young women. These results have important implications for the interpretation of ANC‐based HIV estimates and underscore the importance of population‐based surveys.