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Insights into the timing of repeated testing after treatment for Chlamydia trachomatis: data and modelling study
  1. Janneke Cornelia Maria Heijne1,
  2. Sereina Annik Herzog1,
  3. Christian Lorenz Althaus1,
  4. Guoyu Tao2,
  5. Charlotte Kathleen Kent2,
  6. Nicola Low1
  1. 1Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland
  2. 2Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  1. Correspondence to Janneke Cornelia Maria Heijne, Division of Clinical Epidemiology & Biostatistics, Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, 3012 Bern, Switzerland; jheijne{at}


Objectives The objective of this study was to determine the optimal time interval for a repeated Chlamydia trachomatis (chlamydia) test.

Methods The authors used claims data for US women aged 15–25 years who were enrolled in commercial health insurance plans in the MarketScan database between 2002 and 2006. The authors determined the numbers of initial positive and negative tests that were followed by a repeated test and the positivity of repeated tests. The authors used a dynamic transmission pair model that reflects the partnership formation and separation processes in 15–25 year olds to determine the time course of repeated infections in women under different levels of notifying the current partner. The authors then explored the additional impact of repeated testing uptake on reducing chlamydia prevalence.

Results 40% (4949/12 413) of positive tests were followed by a repeated test compared with 22% (89 119/402 659) of negative tests at any time. Positivity of repeated tests followed by an initial positive test was high: 15% (736) after a positive test versus 3% (2886) after a negative test. The transmission model showed a peak in repeated infections between 2 and 5 months after treatment. For a chlamydia testing uptake of 10% per year, the additional impact of repeated testing on reducing chlamydia population prevalence was modest.

Conclusions The mathematical model predictions support the recommended interval for repeat chlamydia testing. This study provides information that can be used to design randomised controlled trials to determine more effective interventions to prevent chlamydial reinfection.

  • Chlamydia trachomatis
  • women
  • deterministic model
  • preventive health services
  • epidemiology
  • notification
  • control
  • chlamydia
  • mathematical model
  • HIV
  • Neisseria gonorrhoea
  • health service research
  • sexual health
  • chlamydia infection
  • chlamydia
  • STD surveillance
  • epidemiology

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  • Funding This work was supported by the Swiss National Science Foundation (grant numbers 320030_118424, 320030_135654, PDFMP3-124952 and PZ00P3_136737) and the US Centers for Disease Control and Prevention (Atlanta, USA). The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

  • Competing interests In 2010, JCMH and NL received fees from GlaxoSmithKline for attending a meeting about chlamydia vaccines.

  • Provenance and peer review Commissioned; externally peer reviewed.