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Systematic selection of screening participants by risk score in a chlamydia screening programme is feasible and effective
  1. Ingrid V F van den Broek1,
  2. Elfi E H G Brouwers2,
  3. Hannelore M Götz3,
  4. Jan E A M van Bergen4,
  5. Eline L M Op de Coul1,
  6. Johannes S A Fennema5,
  7. Rik H Koekenbier5,
  8. Lydia L Pars4,
  9. Sander M van Ravesteijn3,
  10. Christian J P A Hoebe2
  1. 1Epidemiology and Surveillance Unit, Centre for Infectious Disease Control, National Institute of Public Health and the Environment, Bilthoven, the Netherlands
  2. 2Department of Infectious Diseases, South Limburg Public Health Service, Geleen, the Netherlands
  3. 3Division of Infectious Disease Control, Rotterdam Rijnmond Public Health Service, Rotterdam, the Netherlands
  4. 4STI AIDS Netherlands, Amsterdam, the Netherlands
  5. 5Cluster of Infectious Diseases, Amsterdam Health Service, Amsterdam, the Netherlands
  1. Correspondence to Dr Ingrid V F van den Broek, Epidemiology and Surveillance Unit, Centre for Infectious Disease Control, National Institute of Public Health and the Environment, P.O. Box 1 (nr 75), BA 3720, the Netherlands; ingrid.van.den.broek{at}


Objectives Systematic screening for Chlamydia trachomatis by individual invitation can be optimised by filtering participants on risk profile, excluding people at no or low risk. The authors investigated this technique in a large-scale chlamydia screening programme in the Netherlands in one rural region where relatively low prevalence was expected (<2%).

Methods Invitees were alerted by personal letter to log in to and fill in an 8-item questionnaire. Only invitees with sufficient score could proceed to request a test kit. The authors investigated the effect of selection on participation, positivity and acceptability in three screening rounds and on the number needed to invite and the number needed to screen.

Results The selection led to exclusion of 36% of potential participants and a positivity rate of 4.8% among participants, achieving similar number needed to screen values in the rural and urban areas. Higher scores were clearly related to higher positivity rates. Persons who were excluded from participation did not have a lower response in the next round. The acceptability study revealed disappointment about exclusion of 30% of excluded participants but most approved of the screening set-up.

Conclusions Systematic selection of screening participants by risk score is feasible and successful in realising higher positivity rates. A somewhat stricter selection could be applied in the rural and urban areas of the screening programme. Multiple-item selection with a cut-off total score may work better than, more commonly used, selection by single criteria, especially in low-risk populations. Acceptability of selection is high but could still be improved by better communication on expectations.

  • Chlamydia trachomatis
  • screening
  • risk score
  • selection tool
  • participation
  • positivity
  • acceptability
  • epidemiology (general)
  • surveillance
  • general practice
  • clinical STI care
  • syndromic management
  • HIV
  • epidemiology (molecular)
  • chlamydia infection

Statistics from


  • Funding The Dutch Organisation for Health Research and Development (ZonMw). Project number 12.400.0001. They are the financial administrative office for research for the Ministry of Health, Welfare and Sports; the Chlamydia Screening Implementation Programme is being carried out by request of the Ministry of Health, Welfare and Sport.

  • Competing interests None.

  • Patient consent The data analysis has been done with completely anonymised data; the results are only presented as aggregated per group. Patient questionnaires were voluntary.

  • Ethics approval The ethics committee of the Free University of Amsterdam (METC number: 2007/239) has approved the study, which conforms to national and international legislation.

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

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