title: Modelling the global competing risks of a potential interaction between injectable hormonal contraception and HIV risk.
abstract: BACKGROUND
  Some, but not all, observational studies have suggested an increase in the risk of HIV acquisition for women using injectable hormonal contraception (IHC).
  
  
  METHODS
  We used country-level data to explore the effects of reducing IHC use on the number of HIV infections, the number of live births and the resulting net consequences on AIDS deaths and maternal mortality for each country.
  
  
  RESULTS
  High IHC use coincides with high HIV incidence primarily in southern and eastern Africa. If IHC increases the risk of HIV acquisition, this could generate 27 000-130 000 infections per year globally, 87-88% of which occur in this region. Reducing IHC use could result in fewer HIV infections but also a substantial increase in live births and maternal mortality in countries with high IHC use, high birth rates and high maternal mortality: mainly southern and eastern Africa, South-East Asia, and Central and South America. For most countries, the net impact of reducing IHC use on maternal and AIDS-related deaths is dependent on the magnitude of the assumed IHC-HIV interaction.
  
  
  CONCLUSIONS
  If IHC use increases HIV acquisition risk, reducing IHC could reduce new HIV infections; however, this must be balanced against other important consequences, including unintended pregnancy, which impacts maternal and infant mortality. Unless the true effect size approaches a relative risk of 2.19, it is unlikely that reductions in IHC could result in public health benefit, with the possible exception of those countries in southern Africa with the largest HIV epidemics.
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom.
authors.forename: Ailsa R
authors.initials: AR
authors.lastname: Butler
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Smith
authors.affiliation: USAID, Washington DC, USA.
authors.forename: Chelsea B
authors.initials: CB
authors.lastname: Polis
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Gregson
authors.affiliation: USAID, Washington DC, USA.
authors.forename: David
authors.initials: D
authors.lastname: Stanton
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Hallett
mesh_terms: D000293:Adolescent; D000328:Adult; D000351:Africa, Eastern / Q000453:epidemiology; D000353:Africa, Southern / Q000453:epidemiology; D017280:Condoms / Q000706:statistics & numerical data*; D003270:Contraceptive Agents / Q000008:administration & dosage*; D005193:Family Planning Services; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control* / Q000706:statistics & numerical data; D007267:Injections; D008875:Middle Aged; D015233:Models, Statistical; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D013020:South America / Q000453:epidemiology
chemical_list: D003270:Contraceptive Agents