Floyd, S. et al. (2013) Underestimation of HIV prevalence in surveys when some people already know their status, and ways to reduce the bias. AIDS, 27(2), pp. 233-242. (doi: 10.1097/QAD.0b013e32835848ab) (PMID:22842993)
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Abstract
Objective: To quantify refusal bias due to prior HIV testing, and its effect on HIV prevalence estimates, in general-population surveys. Design: Four annual, cross-sectional, house-to-house HIV serosurveys conducted during 2006–2010 within a demographic surveillance population of 33 000 in northern Malawi. Methods: The effect of prior knowledge of HIV status on test acceptance in subsequent surveys was analysed. HIV prevalence was then estimated using ten adjustment methods, including age-standardization; multiple imputation of missing data; a conditional probability equations approach incorporating refusal bias; using longitudinal data on previous and subsequent HIV results; including self-reported HIV status; and including linked antiretroviral therapy clinic data. Results: HIV test acceptance was 55–65% in each serosurvey. By 2009/2010 79% of men and 85% of women had tested at least once. Known HIV-positive individuals were more likely to be absent, and refuse interviewing and testing. Using longitudinal data, and adjusting for refusal bias, the best estimate of HIV prevalence was 7% in men and 9% in women in 2008/2009. Estimates using multiple imputations were 4.8 and 6.4%, respectively. Using the conditional probability approach gave good estimates using the refusal risk ratio of HIV-positive to HIV-negative individuals observed in this study, but not when using the only previously published estimate of this ratio, even though this was also from Malawi. Conclusion: As the proportion of the population who know their HIV-status increases, survey-based prevalence estimates become increasingly biased. As an adjustment method for cross-sectional data remains elusive, sources of data with high coverage, such as antenatal clinics surveillance, remain important.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Crampin, Professor Mia |
Authors: | Floyd, S., Molesworth, A., Dube, A., Crampin, A. C., Houben, R., Chihana, M., Price, A., Kayuni, N., Saul, J., French, N., and Glynn, J. R. |
College/School: | College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health |
Journal Name: | AIDS |
Publisher: | Lippincott, Williams and Wilkins |
ISSN: | 0269-9370 |
ISSN (Online): | 1473-5571 |
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