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Pitfalls of Internet-accessible diagnostic tests: inadequate performance of a CE-marked Chlamydia test for home use
  1. Claude-Edouard C Michel (cm262{at}cam.ac.uk)
  1. Diagnostics Development Unit, Department of Haematology, University of Cambridge, United Kingdom
    1. Francis G Saison (saison{at}unfpa.org)
    1. Department of Obstetrics-Gynecology, Western Visayas Medical Center, Iloilo City, Philippines
      1. Hrishikesh Joshi (hj255{at}cam.ac.uk)
      1. Diagnostics Development Unit, Department of Haematology, University of Cambridge, United Kingdom
        1. Lourdes M Mahilum-Tapay (lmm{at}drw-ltd.com)
        1. Diagnostics for the Real World (Europe) Ltd., Cambridge Science Park, United Kingdom
          1. Helen H Lee (hl207{at}cam.ac.uk)
          1. Diagnostics Development Unit, Department of Haematology, University of Cambridge, United Kingdom

            Abstract

            Objectives: To evaluate the performance of a CE (Conformitée Européenne)-marked home test for Chlamydia trachomatis (CT) that is available over the Internet.

            Methods: A total of 231 eligible women attending the Social Hygiene Clinic (SHC) or Obstetrics-Gynecology (OB-GYN) Clinic in Iloilo City, Philippines was recruited to an evaluation of the HandiLab-C Chlamydia home test (HandiLab-C). One vaginal swab was tested with HandiLab-C on-site and the second at Cambridge UK with two nucleic acid amplification tests (NAAT), the Roche Amplicor and Abbott m2000. Organism load of NAAT-positive swabs was quantified.

            Results: Concordance between the NAAT’s was high (kappa agreement: 0.984). Using the Abbott assay as the gold standard, sensitivity and specificity of the Roche assay was 97.4% and 100%, respectively. CT prevalence by Abbott was 8.0% (8/100) in OB-GYN Clinic and 23.7% (31/131) at SHC. Sensitivity of HandiLab-C was 12.5% (1/8) and 19.4% (6/31) in OB-GYN and SHC respectively, with specificities of 93.5% (86/92) and 88% (88/100) respectively. Overall positive and negative predictive values of HandiLab-C were 28% and 84.5% respectively. No correlation between HandiLab-C performance and organism load (range: 1.3×102-1.4×107 bacteria/swab) was observed.

            Conclusions: The performance of HandiLab-C is unacceptable, with the test yielding more false positive (18/193) than true positive (7/38) results. It remains accessible via the Internet under various brand names and has retained its CE mark. This situation raises serious concerns about the regulation of diagnostic products available via the Internet and the standards of certain Notified Bodies that issue the CE mark.

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