title: Genital chlamydia prevalence in Europe and non-European high income countries: systematic review and meta-analysis.
abstract: BACKGROUND
  Accurate information about the prevalence of Chlamydia trachomatis is needed to assess national prevention and control measures.
  
  
  METHODS
  We systematically reviewed population-based cross-sectional studies that estimated chlamydia prevalence in European Union/European Economic Area (EU/EEA) Member States and non-European high income countries from January 1990 to August 2012. We examined results in forest plots, explored heterogeneity using the I² statistic, and conducted random effects meta-analysis if appropriate. Meta-regression was used to examine the relationship between study characteristics and chlamydia prevalence estimates.
  
  
  RESULTS
  We included 25 population-based studies from 11 EU/EEA countries and 14 studies from five other high income countries. Four EU/EEA Member States reported on nationally representative surveys of sexually experienced adults aged 18-26 years (response rates 52-71%). In women, chlamydia point prevalence estimates ranged from 3.0-5.3%; the pooled average of these estimates was 3.6% (95% CI 2.4, 4.8, I² 0%). In men, estimates ranged from 2.4-7.3% (pooled average 3.5%; 95% CI 1.9, 5.2, I² 27%). Estimates in EU/EEA Member States were statistically consistent with those in other high income countries (I² 0% for women, 6% for men). There was statistical evidence of an association between survey response rate and estimated chlamydia prevalence; estimates were higher in surveys with lower response rates, (p = 0.003 in women, 0.018 in men).
  
  
  CONCLUSIONS
  Population-based surveys that estimate chlamydia prevalence are at risk of participation bias owing to low response rates. Estimates obtained in nationally representative samples of the general population of EU/EEA Member States are similar to estimates from other high income countries.
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Finkenhubelweg 11, CH-3012, Bern, Switzerland.
authors.forename: Shelagh M
authors.initials: SM
authors.lastname: Redmond
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Finkenhubelweg 11, CH-3012, Bern, Switzerland.
authors.forename: Karin
authors.initials: K
authors.lastname: Alexander-Kisslig
authors.affiliation: HIV & STI Department, National Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, United Kingdom.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Woodhall
authors.affiliation: Unit of Epidemiology and Surveillance, RIVM/Centre for Infectious Disease Control Netherlands, PO Box 1, 3720 BA, Bilthoven, Netherlands.
authors.forename: Ingrid V F
authors.initials: IV
authors.lastname: van den Broek
authors.affiliation: University of Amsterdam, 1012 WX Amsterdam, Netherlands and STI AIDS Netherlands, Keizersgracht 390, 1016 GB, Amsterdam, Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: van Bergen
authors.affiliation: Infectious Diseases Epidemiology, School of Public Health, Imperial College London, St Mary's Campus, Norfolk Place, London, W2 1PG, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Ward
authors.affiliation: Department of Public Health, University of Tartu, Ravila 19, 50411, Tartu, Estonia.
authors.forename: Anneli
authors.initials: A
authors.lastname: Uusküla
authors.affiliation: Department of Clinical Microbiology, Uppsala University Hospital, SE-751 85, Uppsala, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Herrmann
authors.affiliation: Department of Public Health Interventions, Randers Hospital, Skovlyvej, 8900, Randers, Denmark.
authors.forename: Berit
authors.initials: B
authors.lastname: Andersen
authors.affiliation: Department of Infectious Disease Control, Municipal Public Health Service Rotterdam-Rijnmond, PO Box 70032, 3000 LP, Rotterdam, Netherlands.
authors.forename: Hannelore M
authors.initials: HM
authors.lastname: Götz
authors.affiliation: European Centre for Disease Prevention and Control (ECDC), Tomtebodavägen 11 A, 17183, Stockholm, Sweden.
authors.forename: Otilia
authors.initials: O
authors.lastname: Sfetcu
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Finkenhubelweg 11, CH-3012, Bern, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Low
mesh_terms: D000293:Adolescent; D000328:Adult; D002690:Chlamydia Infections / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D019049:Developed Countries; D005060:Europe / Q000453:epidemiology; D005260:Female; D005835:Genitalia / Q000382:microbiology*; D006801:Humans; D008297:Male; D015995:Prevalence; D011897:Random Allocation; D055815:Young Adult