title: Factors associated with repeated refusal to participate in longitudinal population-based HIV surveillance in rural South Africa: an observational study, regression analyses.
abstract: BACKGROUND
  For many estimation purposes, individuals who repeatedly refuse to participate in longitudinal HIV surveillance pose a bigger threat to valid inferences than individuals who participate at least occasionally. We investigate the determinants of repeated refusal to consent to HIV testing in a population-based longitudinal surveillance in rural South Africa.
  
  
  METHODS
  We used data from two years (2005 & 2006) of the annual HIV surveillance conducted by the Africa Centre for Health and Population Studies, linking the HIV surveillance data to demographic and socioeconomic data. The outcome for the analysis was "repeated refusal". Demographic variables included sex, age, highest educational attainment, and place of residence. We also included a measure of wealth and the variable "ever had sex". To compare the association of each variable with the outcome, unadjusted odds ratios and standard errors were estimated. Multivariable logistic regression was used to estimate adjusted odds ratios and their standard errors. Data were analyzed using STATA 10.0.
  
  
  RESULTS
  Of 15,557 eligible individuals, 46% refused to test for HIV in both rounds. Males were significantly more likely than females to repeatedly refuse testing. Holding all other variables constant, individuals in the middle age groups were more likely to repeatedly refuse testing compared with younger and older age groups. The odds of repeated refusal increased with increasing level of education and relative wealth. People living in urban areas were significantly more likely to repeatedly refuse an HIV test than people living in peri-urban or rural areas. Compared to those who had ever had sex, both males and females who had not yet had sex were significantly more likely to refuse to participate.
  
  
  CONCLUSIONS
  The likelihood of repeated refusal to test for HIV in this longitudinal surveillance increases with education, wealth, urbanization, and primary sexual abstinence. Since the factors determining repeated HIV testing refusal are likely associated with HIV status, it is critical that selection effects are controlled for in the analysis of HIV surveillance data. Interventions to increase consent to HIV testing should consider targeting the relatively well educated and wealthy, people in urban areas, and individuals who have not yet sexually debuted.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Giordano
authors.affiliation: Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Somkhele, South Africa ; Department of Global Health and Population, Harvard School of Public Health, Harvard University, Boston, USA.
authors.forename: Till
authors.initials: T
authors.lastname: Bärnighausen
authors.affiliation: Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Somkhele, South Africa ; London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Nuala
authors.initials: N
authors.lastname: McGrath
authors.affiliation: Department of Health Behavior & Health Education, School of Public Health, University of Michigan, Ann Arbor, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Snow
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, USA.
authors.forename: Siobán
authors.initials: S
authors.lastname: Harlow
authors.affiliation: Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Somkhele, South Africa ; Centre for Paediatric Epidemiology and Biostatistics, University College London Institute of Child Health, UK.
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Newell