title: Classification of incidence and prevalence of certain sexually transmitted infections by world regions.
abstract: OBJECTIVE
  This study sought to assess if there is a meaningful way in which variations in sexually transmitted infection (STI) prevalence can be classified at the level of world regions.
  
  
  METHODS
  Linear regression was performed to assess if the incidence and prevalence of six STIs (HIV, herpes simplex virus type 2, chlamydia, gonorrhea, syphilis, and trichomoniasis) by world region was positively correlated. Partitioning around medoids (PAM) was then used to assess if the regions of the world can be classified according to the incidence and prevalence of these STIs.
  
  
  RESULTS
  We found evidence that STI incidence/prevalence varies considerably in different regions around the world. Linear regression revealed that the incidence and prevalence of certain STIs by world region was positively correlated (Pearson's correlation coefficient varied from 0.664 to 0.985). PAM provided support for dividing the world regions into two, three, or four STI incidence/prevalence categories, but it provided most support for the two-category system. In each of these systems the East Asia/Pacific and North Africa/Middle East regions were in the lowest STI category and Sub-Saharan Africa was the only region in the high STI category.
  
  
  CONCLUSIONS
  The incidence and prevalence of certain STIs by world region are positively correlated. The world regions can be meaningfully classified according to STI incidence/prevalence.
authors.affiliation: Clinical HIV/STD Unit, Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium; Division of Infectious Diseases and HIV Medicine, Department of Medicine, Groote Schuur Hospital, Observatory, South Africa. Electronic address: chriskenyon0@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Kenyon
authors.affiliation: Clinical HIV/STD Unit, Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Buyze
authors.affiliation: Clinical HIV/STD Unit, Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Colebunders
mesh_terms: D000349:Africa / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D006069:Gonorrhea / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016014:Linear Models; D015201:Meta-Analysis as Topic; D008877:Middle East / Q000453:epidemiology; D015995:Prevalence; D012749:Sexually Transmitted Diseases / Q000145:classification / Q000453:epidemiology*; D013587:Syphilis / Q000453:epidemiology; D014245:Trichomonas Infections / Q000453:epidemiology
keywords: Bacterial vaginosis; Chlamydia; Gonorrhea; HIV; Herpes simplex virus type 2; Human papillomavirus; Syphilis; Trichomoniasis