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Gonorrhoea and chlamydia in persons with HIV: number needed to screen
  1. Susan Tuddenham1,
  2. Khalil G Ghanem1,
  3. Kelly A Gebo1,
  4. Richard D Moore1,
  5. William Christopher Mathews2,
  6. Allison Agwu3,
  7. Kenneth Mayer4,5,6,
  8. Christina Schumacher3,
  9. Julia Raifman7,
  10. Stephen A Berry1
  1. 1 Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
  2. 2 Department of Medicine, University of California San Diego, San Diego, California, USA
  3. 3 Department of Pediatrics, Johns Hopkins University, Baltimore, Maryland, USA
  4. 4 Fenway Health, The Fenway Institute, Boston, Massachusetts, USA
  5. 5 Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
  6. 6 Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
  7. 7 Department of Health Law, Policy and Management, Boston University School of Public Health, Boston, Massachusetts, USA
  1. Correspondence to Dr Susan Tuddenham, Department of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA; studden1{at}


Objectives Current guidelines recommend screening sexually active persons with HIV (PWH) for Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) at least annually. Yet, screening rates in many HIV clinics remain low. In this study, we estimated the number needed to screen (NNS) to detect a NG and/or CT infection at each anatomic site among different subpopulations of PWH. NNS provides a concrete, practical measure to aid in assessing the practical impact of screening.

Methods We included adults in care at three HIV Research Network sites in 2011–2014. Restricting to first tests within each year, annual NNS was defined as number of persons tested divided by number positive. We computed urogenital and extragenital NNS by age and risk group (women, men who have sex with women (MSW) and men who have sex with men (MSM)).

Results A total of 16 864 NG/CT tests were included. Among patients aged ≤25 years, urogenital NNS was similar among women (15 (95% CI 6 to 71)), MSW (21 (95% CI 6 to 167)) and MSM (20 (95% CI 12 to 36)). Over 25, urogenital NNS increased to a greater extent for women (363 (95% CI 167 to 1000)) and MSW (160 (95% CI 100 to 333)) than MSM (46 (95% CI 38 to 56)). The increase for women versus MSM >25 remained significant (p<0.01) in multivariable analysis. Among MSM, rectal NNS was 5 (95% CI 3 to 7) and 10 (95% CI 9 to 12) for ≤25 and for >25 years and pharyngeal NNS values were 8 (95% CI 5 to 13) and 20 (95% CI 16 to 24).

Conclusions These findings suggest the importance of regular, at least annual NG/CT screening, particularly extragenital, of HIV positive MSM of all ages. They provide some support for age-based cutoffs for women and MSW (eg, universal screening for those aged ≤25 and targeted screening for those aged >25 years).

  • gonorrhea
  • chlamydia
  • HIV
  • sexually transmitted diseases

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  • Handling editor Gwenda Hughes

  • Contributors KG and SB conceived of the project, ST and SB conducted the analysis. JS contributed to the analysis. CS provided substantive comments and statistical support. KG, KM, AA, RM, and WM contributed to drafting and revising the paper.

  • Funding This research was supported by the Agency for Healthcare Research and Quality (HHSA290201100007C), the Health Resources and Services Administration (HHSH250201600009C), the National Institutes of Health (U01 DA036935, P30 AI094189), and the Clinical Investigation and Biostatistics Core of the UC San Diego Center for AIDS Research (P30 AI036214). Additionally, Susan Tuddenham’s work is supported by NIH grant K23AI125715, Stephen Berry’s work is supported by NIH grant K23AI084854.

  • Competing interests Richard Moore was a consultant for Medscape, LLC until 2018, Susan Tuddenham is a consultant for Biofire Diagnostics.

  • Patient consent for publication Not required.

  • Ethics approval Institutional review boards at the individual sites and the data coordinating centre at Johns Hopkins University School of Medicine (IRB number: NA_00005753) approved the collection and use of these data.

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

  • Data sharing statement HIV Research Network data are available for scientific collaboration. Please see