title: Do HIV prevalence trends in antenatal clinic surveillance represent trends in the general population in the antiretroviral therapy era? The case of Manicaland, East Zimbabwe.
abstract: OBJECTIVE
  National estimates of HIV trends in generalized epidemics rely on HIV prevalence data from antenatal clinic (ANC) surveillance. We investigate whether HIV prevalence trends in ANC data reflect trends in men and women in the general population during the scale-up of antiretroviral therapy (ART) in Manicaland, Zimbabwe.
  
  
  METHODS
  Trends in HIV prevalence in local ANC attendees and adults aged 15-49 years in towns, agricultural estates, and villages were compared using five rounds of parallel ANC (N = 1200) and general-population surveys (N = 10 000) and multivariable log-linear regression. Changes in the age pattern of HIV prevalence and the age distribution of ANC attendees were compared with those in the general population. Age-specific pregnancy prevalence rates were compared by HIV infection and ART status.
  
  
  RESULTS
  Cumulatively, from 1998-2000 to 2009-2011, HIV prevalence fell by 60.0% (95% confidence interval, 51.1-67.3%) in ANC surveillance data and by 34.3% (30.8-37.7%) in the general population. Most of the difference arose following the introduction of ART (2006-2011). The estates and villages reflected this overall pattern but HIV prevalence in the towns was lower at local ANCs than in the general population, largely because of attendance by pregnant women from outlying (lower prevalence) areas. The ageing of people living with HIV in the general population (52.4% aged >35 years, 2009-2011) was under-represented in the ANC data (12.6%) because of lower fertility in older and HIV-infected women.
  
  
  CONCLUSIONS
  After the introduction of ART in Manicaland, HIV prevalence declined more steeply in ANC surveillance data than in the general population. Models used for HIV estimates must reflect this change in bias.
authors.affiliation: aDepartment of Infectious Disease Epidemiology, Imperial College London School of Public Health, London, United Kingdom bBiomedical Research and Training Institute cAIDS and TB Unit, Zimbabwe Ministry of Health and Child Welfare, Harare, Zimbabwe.
authors.forename: Simon
authors.initials: S
authors.lastname: Gregson
authors.forename: Kanika
authors.initials: K
authors.lastname: Dharmayat
authors.forename: Monique
authors.initials: M
authors.lastname: Pereboom
authors.forename: Albert
authors.initials: A
authors.lastname: Takaruza
authors.forename: Owen
authors.initials: O
authors.lastname: Mugurungi
authors.forename: Nadine
authors.initials: N
authors.lastname: Schur
authors.forename: Constance A
authors.initials: CA
authors.lastname: Nyamukapa
mesh_terms: D000293:Adolescent; D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active / Q000706:statistics & numerical data; D062665:Epidemiological Monitoring; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D015995:Prevalence; D055815:Young Adult; D015030:Zimbabwe / Q000453:epidemiology
chemical_list: D044966:Anti-Retroviral Agents