title: Comparison of two Gram stain point-of-care systems for urogenital gonorrhoea among high-risk patients: diagnostic accuracy and cost-effectiveness before and after changing the screening algorithm at an STI clinic in Amsterdam.
abstract: OBJECTIVE
  To compare point-of-care (POC) systems in two different periods: (1) before 2010 when all high-risk patients were offered POC management for urogenital gonorrhoea by Gram stain examination; and (2) after 2010 when only those with symptoms were offered Gram stain examination.
  
  
  METHODS
  Retrospective comparison of a Gram stain POC system to all high-risk patients (2008-2009) with only those with urogenital symptoms (2010-2011) on diagnostic accuracy, loss to follow-up, presumptively and correctly treated infections and diagnostic costs. Culture was the reference diagnostic method.
  
  
  RESULTS
  In men the sensitivity of the Gram stain was 95.9% (95% CI 93.1% to 97.8%) in 2008-2009 and 95.4% (95% CI 93.7% to 96.8%) in 2010-2011, and in women the sensitivity was 32.0% (95% CI 19.5% to 46.7%) and 23.1% (95% CI 16.1% to 31.3%), respectively. In both periods the overall specificity was high (99.9% (95% CI 99.8% to 100%) and 99.8% (95% CI 99.7% to 99.9%), respectively). The positive predictive value (PPV) and negative predictive value (NPV) before and after 2010 were also high: PPV 97.0% (95% CI 94.5% to 98.5%) and 97.7% (95% CI 96.3% to 98.6%), respectively; NPV 99.6% (95% CI 99.4% to 99.7%) and 98.8% (95% CI 98.5% to 99.0%), respectively. There were no differences between the two time periods in loss to follow-up (7.1% vs 7.0%). Offering Gram stains only to symptomatic high-risk patients as opposed to all high-risk patients saved €2.34 per correctly managed consultation (a reduction of 7.7%).
  
  
  CONCLUSIONS
  The sensitivity of the Gram stain is high in men but low in women. When offered only to high-risk patients with urogenital symptoms, the cost per correctly managed consultation is reduced by 7.7% without a significant difference in accuracy and loss to follow-up.
authors.affiliation: STI Outpatient Clinic, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Bartelsman
authors.affiliation: Department of Biomedical Research, Royal Tropical Institute, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Straetemans
authors.affiliation: Department of Development Policy and Practice, Royal Tropical Institute, Amsterdam, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Vaughan
authors.affiliation: Department of Biomedical Research, Royal Tropical Institute, Amsterdam, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Alba
authors.affiliation: STI Outpatient Clinic, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands Department of Research, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands Public Health Laboratory, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands.
authors.forename: M S
authors.initials: MS
authors.lastname: van Rooijen
authors.affiliation: STI Outpatient Clinic, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands Department of Dermatology, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: W R
authors.initials: WR
authors.lastname: Faber
authors.affiliation: STI Outpatient Clinic, Public Health Service of Amsterdam (GGD Amsterdam), Amsterdam, The Netherlands Department of Dermatology, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands Center for Infection and Immunology Amsterdam (CINIMA), Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: H J C
authors.initials: HJ
authors.lastname: de Vries
mesh_terms: D000328:Adult; D000465:Algorithms; D000554:Ambulatory Care Facilities; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D017963:Azithromycin / Q000627:therapeutic use*; D002443:Ceftriaxone / Q000627:therapeutic use; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000191:economics; D060085:Coinfection; D003362:Cost-Benefit Analysis; D005260:Female; D005840:Gentian Violet; D006069:Gonorrhea / Q000175:diagnosis* / Q000188:drug therapy / Q000191:economics; D006801:Humans; D008297:Male; D010619:Phenazines; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D015231:Sexually Transmitted Diseases, Bacterial / Q000175:diagnosis* / Q000188:drug therapy / Q000191:economics; D014566:Urogenital System / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; C035863:Gram's stain; D010619:Phenazines; D002443:Ceftriaxone; D017963:Azithromycin; D005840:Gentian Violet