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Original article
Point-of-care management of urogenital Chlamydia trachomatis via Gram-stained smear analysis in male high-risk patients. Diagnostic accuracy and cost-effectiveness before and after changing the screening indication at the STI Clinic in Amsterdam
  1. M Bartelsman1,
  2. M S van Rooijen1,2,3,
  3. S Alba4,
  4. K Vaughan5,
  5. W R Faber1,6,
  6. M Straetemans2,
  7. H J C de Vries1,6,7
  1. 1STI Outpatient Clinic, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands
  2. 2Department of Research, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands
  3. 3Public Health Laboratory, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands
  4. 4KIT Biomedical Research, Royal Tropical Institute, Amsterdam, The Netherlands
  5. 5KIT Health, Royal Tropical Institute, Amsterdam, The Netherlands
  6. 6Department of Dermatology, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands
  7. 7Center for Infection and Immunology Amsterdam (CINIMA), Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Professor Henry de Vries, Public Health Service of Amsterdam, Cluster of Infectious Diseases, STI Outpatient Clinic, Weesperplein 1, Amsterdam 1018 WZ, The Netherlands; h.j.devries{at}amc.nl

Abstract

Objectives To measure the effect of changing the point-of-care (POC) testing algorithm of urogenital chlamydia for all male high-risk patients to those with only symptoms with respect to: diagnostic accuracy, loss to follow-up, correctly managed consultations and costs.

Methods Retrospective comparison of the diagnostic accuracy and cost-effectiveness of Gram-stained urethral smear analysis for the POC management of urogenital Chlamydia trachomatis infections. Between 2008 and 2009 Gram-stained urethral smear analysis was offered to all men irrespective of symptoms; between 2010 and 2011 only to those with symptoms. The Aptima CT assay was the reference diagnostic test.

Results The number of examined Gram-stained smears in the two periods was respectively 7185 (2008–2009 period) and 18 852 (2010–2011 period). The sensitivity of the Gram stain analysis was respectively 83.8% (95% CI 81.2% to 86.1%) and 91.0% (95% CI 89.5% to 92.3%) (p<0.001). The specificity was respectively 74.1% (95% CI 73.0% to 75.2%) and 53.1% (95% CI 51.8% to 54.4%) (p<0.001). The positive predictive value was low in both periods, respectively 31.7% (95% CI 29.8% to 33.6%) and 35.6% (95% CI 34.1% to 37.1%) (p=0.002), whereas the negative predictive value was high, respectively 97.0% (95% CI 96.4% to 97.4%) and 95.4% (95% CI 94.6% to 96.1%) (p=0.002). The loss to follow-up rate between 2008–2009 and 2010–2011 was, respectively, 1.8% (95% CI 1.0% to 2.9%) vs 2.3% (95% CI 1.7% to 3.0%) (p=0.36). There was a small difference in overtreatment, 68.0% (95% CI 66.0% to 69.8%) vs 64.1% (95% CI 62.6% to 65.5%) (p=0.001). The cost per correctly managed consultation was 14.3% lower in the 2010–2011 period (€94.31 vs €80.82). The percentage of delayed treated infections was significantly lower in the 2008–2009 period (10.5%) compared with the 2010–2011 period (22.8%) (p<0.001).

Conclusions With a high sensitivity in male high-risk patients, the Gram-stained urethral smear is a useful POC test to detect urogenital C. trachomatis. When offered only to men with urogenital symptoms the specificity decreases but the cost per correctly managed consultation is reduced with 14.3% without a significant difference in loss to follow-up but with a significantly higher rate of delayed treatment.

  • COST-EFFECTIVENESS
  • TESTING
  • CHLAMYDIA TRACHOMATIS

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