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Can we use postal surveys with anonymous testing to monitor chlamydia prevalence in young women in England? Pilot study incorporating randomised controlled trial of recruitment methods
  1. Sarah C Woodhall1,2,
  2. Tom Nichols3,
  3. Sarah Alexander4,
  4. Filomeno Coelho da Silva4,
  5. Catherine H Mercer2,
  6. Catherine Ison4,
  7. O Noel Gill1,
  8. Kate Soldan1
  1. 1Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK
  2. 2Research Department of Infection and Population Health, University College London, London, UK
  3. 3Statistics Unit, Public Health England, London, UK
  4. 4Microbiology Services, Public Health England, London, UK
  1. Correspondence to Sarah Woodhall, HIV & STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK; sarah.woodhall{at}


Objectives Chlamydia prevalence in the general population is a potential outcome measure for the evaluation of chlamydia control programmes. We carried out a pilot study to determine the feasibility of using a postal survey for population-based chlamydia prevalence monitoring.

Methods Postal invitations were sent to a random sample of 2000 17-year-old to 18-year-old women registered with a general practitioner in two pilot areas in England. Recipients were randomised to receive either a self-sampling kit (n=1000), a self-sampling kit and offer of £5 voucher on return of sample (n=500) or a self-sampling kit on request (n=500). Participants returned a questionnaire and self-taken vulvovaginal swab sample for unlinked anonymous Chlamydia trachomatis testing. Non-responders were sent a reminder letter 3 weeks after initial invitation. We calculated the participation rate (number of samples returned/number of invitations sent) and cost per sample returned (including cost of consumables and postage) in each group.

Results A total of 155/2000 (7.8%) samples were returned with consent for testing. Participation rates varied by invitation group: 7.8% in the group who were provided with a self-sampling kit, 14% in the group who were also offered a voucher and 1.0% in the group who were not sent a kit. The cost per sample received was lowest (£36) in the group who were offered both a kit and a voucher.

Conclusions The piloted survey methodology achieved low participation rates. This approach is not suitable for population-based monitoring of chlamydia prevalence among young women in England.

Study registration number (UKCRN ID 10913).


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