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Impact of intensified testing for urogenital Chlamydia trachomatis infections: a randomised study with 9-year follow-up
  1. Berit Andersen1,2,
  2. Irene van Valkengoed3,
  3. Ineta Sokolowski1,
  4. Jens K Møller4,
  5. Lars Østergaard5,
  6. Frede Olesen1
  1. 1Research Unit for General Practice, Aarhus, Denmark
  2. 2Department of Public Health Programmes, Randers Hospital, Denmark
  3. 3Department of Social Medicine, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
  4. 4Department of Clinical Microbiology, Aarhus University Hospital Skejby, Aarhus, Denmark
  5. 5Department of Infectious Diseases, Aarhus University Hospital Skejby, Aarhus, Denmark
  1. Correspondence to Dr Berit Andersen, Department of Public Health Interventions, Randers Hospital, Skovlyvej, 8900 Randers, Denmark; ba{at}


Background DNA amplification assays are increasingly being used to facilitate the testing of asymptomatic individuals for urogenital Chlamydia trachomatis. The long-term clinical benefit in terms of avoided infertility and ectopic pregnancy is unknown.

Methods In 1997, 15 459 women and 14 980 men aged 21–23 years were living in Aarhus County, Denmark. A random sample of 4000 women and 5000 men was contacted by mail and offered the opportunity to be tested for C trachomatis by means of a sample obtained at home and mailed directly to the laboratory. The remaining 11 459 women and 9980 men received usual care and constituted the control population. All men and women were subsequently followed for 9 years by the use of Danish health registers. Data were collected on pelvic inflammatory disease (PID), ectopic pregnancy (EP), infertility diagnoses, in-vitro fertilisation (IVF) treatment and births in women, and on epididymitis in men. The intervention and control groups were compared using Cox regression analyses and the intention-to-screen principle.

Results Among women, no differences were found between the intervention group and the control group: HR (95% CI) for PID 1.12 (0.70 to 1.79); EP 0.97 (0.63 to 1.51); infertility 0.87 (0.71 to 1.07); IVF treatment 0.88 (0.62 to 1.26) and births 1.02 (0.95 to 1.10). In men, the HR for epididymitis was 1.25 (0.70 to 2.24).

Conclusions A population-based offer to be tested for urogenital C trachomatis infection by the use of non-invasive samples and DNA amplification did not reduce the long-term risk of reproductive complications in women or of epididymitis in men.

Trial registration number in NCT 00827970.

  • Chlamydia trachomatis
  • ectopic pregnancy
  • ectopy
  • epididymitis
  • infertility
  • pelvic inflammatory disease
  • random allocation
  • STD control

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  • Funding This study received financial support from the Danish Medical Research Council (grant no 22-02-0540), the NOVO Foundation and the Research Foundation in Aarhus County. The funding organisations did not influence any part of the study and the researchers are independent from the funders.

  • Competing interests None.

  • Ethics approval The study was approved by the local ethical committee in the County of Aarhus and by the Danish Data Protection Agency.

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

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