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The performance of non-NAAT point-of-care (POC) tests and rapid NAAT tests for chlamydia and gonorrhoea infections. An assessment of currently available assays
  1. Gary Brook
  1. Correspondence to Dr Gary Brook, Department of Genitourinary Medicine and HIV, Central Middlesex Hospital, London North West Healthcare NHS Trust, Patrick Clements Clinic, Central Middlesex Hospital, Acton Lane, London NW10 7NS, UK; gary.brook{at}nhs.net

Abstract

Objectives To identify point-of-care (POC) and rapid nucleic acid amplification techniques (NAATs) for the diagnosis of chlamydia and gonorrhoea and assess their utility.

Methods Literature search for available POC and rapid NAATs. The performance from the best-performing assays were applied hypothetically to patients in the clinic in which 100 consecutive patients with chlamydia and 100 with gonorrhoea were diagnosed in 1737 and 4575 patients respectively, with 44/100 and 54/100 treated at first attendance, respectively.

Results 11 POC and 1 rapid NAAT were identified. Published performances for the best POC for chlamydia (CRT) were: sensitivity 41%–87%, specificity 89%–99.6%. Our data suggest that if this assay was used instead of our current NAAT, for every 100 patients diagnosed currently, 23–46 extra patients would be treated at first attendance; 10–35 would go undiagnosed with 7–191 false-positives. Best chlamydia rapid NAAT (GeneXpert): sensitivity 97.5%–98.7%, specificity 99.4%–99.9%. Anticipated performance for every 100 patients diagnosed currently: 0 extra patients treated at first attendance, 1–3 undiagnosed, 0–2 false-positives. Best POC for gonorrhoea (GC Check): sensitivity 54%–70%, specificity 97%–98%. Anticipated performance for every 100 patients diagnosed currently: 14–18 extra patients treated at first attendance, 28–32 undiagnosed, 92–137 false-positives. Best rapid NAAT for gonorrhoea (GeneXpert): sensitivity 96%–100%, specificity 99.9%–100%. Anticipated performance for every 100 patients diagnosed currently: 0 extra patients treated at first attendance, 0–4 undiagnosed, 0–5 false-positives. Rapid NAAT would reduce time to treatment by 4 days for initially untreated patients.

Conclusions POC assays would need to be used in conjunction with a NAAT, increasing early treatment rates expense and false-positive results. The rapid NAAT could be used alone, with a reduction in average time-to-treat and a small reduction in sensitivity and specificity.

  • CHLAMYDIA INFECTION
  • GONORRHOEA
  • MODELING
  • DIAGNOSIS

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