title: Errors generated by a point-of-care CD4+ T-lymphocyte analyser: a retrospective observational study in nine countries.
abstract: OBJECTIVE
  To estimate the proportion of invalid results generated by a CD4+ T-lymphocyte analyser used by Médecins Sans Frontières (MSF) in field projects and identify factors associated with invalid results.
  
  
  METHODS
  We collated 25,616 CD4+ T-lymphocyte test results from 39 sites in nine countries for the years 2011 to 2013. Information about the setting, user, training, sampling technique and device repair history were obtained by questionnaire. The analyser performs a series of checks to ensure that all steps of the analysis are completed successfully; if not, an invalid result is reported. We calculated the proportion of invalid results by device and by operator. Regression analyses were used to investigate factors associated with invalid results.
  
  
  RESULTS
  There were 3354 invalid test results (13.1%) across 39 sites, for 58 Alere PimaTM devices and 180 operators. The median proportion of errors per device and operator was 12.7% (interquartile range, IQR: 10.3-19.9) and 12.1% (IQR: 7.1-19.2), respectively. The proportion of invalid results varied widely by country, setting, user and device. Errors were not associated with settings, user experience or the number of users per device. Tests performed on capillary blood samples were significantly less likely to generate errors compared to venous whole blood.
  
  
  CONCLUSIONS
  The Alere Pima CD4+ analyser generated a high proportion of invalid test results, across different countries, settings and users. Most error codes could be attributed to the operator, but the exact causes proved difficult to identify. Invalid results need to be factored into the implementation and operational costs of routine CD4+ T-lymphocyte testing.
authors.affiliation: Médecins Sans Frontières (MSF), Southern Africa Medical Unit (SAMU), Waverly Business Park, 303 A&B, Cape Town, South Africa .
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Fajardo
authors.affiliation: Médecins Sans Frontières (MSF), Southern Africa Medical Unit (SAMU), Waverly Business Park, 303 A&B, Cape Town, South Africa .
authors.forename: Carol
authors.initials: C
authors.lastname: Metcalf
authors.affiliation: MSF, Operational Centre Amsterdam, Netherlands .
authors.forename: Erwan
authors.initials: E
authors.lastname: Piriou
authors.affiliation: MSF, Operational Centre Paris, France .
authors.forename: Monique
authors.initials: M
authors.lastname: Gueguen
authors.affiliation: MSF, Epicentre Paris, France .
authors.forename: David
authors.initials: D
authors.lastname: Maman
authors.affiliation: MSF, Operational Centre Brussels, Belgium .
authors.forename: Pascale
authors.initials: P
authors.lastname: Chaillet
authors.affiliation: MSF, Khayelitsha, South Africa .
authors.forename: Vivian
authors.initials: V
authors.lastname: Cox
authors.affiliation: Médecins Sans Frontières (MSF), Southern Africa Medical Unit (SAMU), Waverly Business Park, 303 A&B, Cape Town, South Africa .
authors.forename: Maryam B
authors.initials: MB
authors.lastname: Rumaney
authors.affiliation: MSF, Roma, Lesotho .
authors.forename: Syanness
authors.initials: S
authors.lastname: Tunggal
authors.affiliation: MSF, Diagnostic Network, Amsterdam, Netherlands .
authors.forename: Cara
authors.initials: C
authors.lastname: Kosack
authors.affiliation: MSF, Access Campaign, Geneva, Switzerland .
authors.forename: Teri
authors.initials: T
authors.lastname: Roberts
mesh_terms: D016477:Artifacts; D001800:Blood Specimen Collection; D018791:CD4 Lymphocyte Count / Q000379:methods*; D006801:Humans; D019095:Point-of-Care Systems; D011361:Professional Competence; D012044:Regression Analysis; D012189:Retrospective Studies