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Chlamydia infection, pelvic inflammatory disease, ectopic pregnancy and infertility: cross-national study
  1. Nicole Bender1,
  2. Björn Herrmann2,
  3. Berit Andersen3,4,
  4. Jane S Hocking5,
  5. Jan van Bergen6,7,
  6. Jane Morgan8,
  7. Ingrid VF van den Broek7,
  8. Marcel Zwahlen1,
  9. Nicola Low1
  1. 1Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
  2. 2Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
  3. 3Department of Public Health Programmes, Randers Regional Hospital, Randers, Denmark
  4. 4Research Unit for General Practice, Aarhus, Denmark
  5. 5Centre for Women's Health, Gender and Society, Melbourne School of Population Health, University of Melbourne, Melbourne, Victoria, Australia
  6. 6STI AIDS Netherlands, the Netherlands
  7. 7Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, the Netherlands
  8. 8Sexual Health Clinic, Waikato Hospital, Hamilton, New Zealand
  1. Correspondence to Professor Nicola Low, Institute of Social and Preventive Medicine, University of Bern, Bern CH-3012, Switzerland; low{at}


Objectives To describe, using routine data in selected countries, chlamydia control activities and rates of chlamydia infection, pelvic inflammatory disease (PID), ectopic pregnancy and infertility and to compare trends in chlamydia positivity with rates of PID and ectopic pregnancy.

Methods Cross-national comparison including national data from Australia, Denmark, the Netherlands, New Zealand, Sweden and Switzerland. Routine data sources about chlamydia diagnosis and testing and International Classification of Disease-10 coded diagnoses of PID, ectopic pregnancy and infertility in women aged 15–39 years from 1999 to 2008 were described. Trends over time and relevant associations were examined using Poisson regression.

Results Opportunistic chlamydia testing was recommended in all countries except Switzerland, but target groups differed. Rates of chlamydia testing were highest in New Zealand. Chlamydia positivity was similar in all countries with available data (Denmark, New Zealand and Sweden) and increased over time. Increasing chlamydia positivity rates were associated with decreasing PID rates in Denmark and Sweden and with decreasing ectopic pregnancy rates in Denmark, New Zealand and Sweden. Ectopic pregnancy rates appeared to increase over time in 15–19-year-olds in several countries. Trends in infertility diagnoses were very variable.

Conclusions The intensity of recommendations about chlamydia control varied between countries but was not consistently related to levels of chlamydia diagnosis or testing. Relationships between levels of chlamydia infection and complication rates between or within countries over time were not straightforward. Development and validation of indicators of chlamydia-related morbidity that can be compared across countries and over time should be pursued.

  • Chlamydia trachomatis
  • pelvic inflammatory disease
  • ectopic pregnancy
  • infertility
  • epidemiology
  • surveillance
  • LGV
  • STD behavioural
  • STD patients
  • STD clinic
  • STDS
  • genital infection
  • sexual behaviour
  • STD control
  • chlamydia infection
  • epidemiology (general)
  • screening
  • general practice
  • TB
  • HSV-1
  • HSV-2
  • chlamydia

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  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.