title: Proficiency testing (external quality assessment) of drug detection in oral fluid.
abstract: Eighteen external quality assessment (proficiency testing) samples were prepared from client specimens collected with the Intercept oral fluid collection device and by spiking drug-free oral fluid. Samples were circulated in pairs at quarterly intervals to 13 UK and USA based laboratories for analysis by a panel of OraSure micro-plate Intercept enzyme immunoassay kits and hyphenated mass spectrophotometric techniques. During the survey, there was a single case of non-specificity in a false report for methadone. The major errors were of lack of sensitivity relative to the concentration thresholds specified for the immunoassays. The sensitivity for overall "present"/"not found" reports calculated as true positives/(true positives+false negatives) were for the amphetamine specific assay 50%, methyl-amphetamines 93%, barbiturates 64%, cannabinoids 73%, cocaine and metabolites 100%, benzodiazepines 69%, methadone 95%, opiates 79% (opiates excluding oxycodone 93%), phencyclidine 93% and human gamma-globulin 97%. A small number of the sensitivity errors were attributable to errors in chromatographic confirmation techniques.
authors.affiliation: Altrix Healthcare plc, Birchwood Science Park, Warrington WA3 7BP, UK. j.clarke@altrix.com
authors.forename: Joe
authors.initials: J
authors.lastname: Clarke
authors.forename: John F
authors.initials: JF
authors.lastname: Wilson
mesh_terms: D019411:Clinical Laboratory Techniques / Q000592:standards*; D005554:Forensic Medicine / Q000592:standards; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D009061:Mouth Mucosa / Q000737:chemistry*; D011786:Quality Control; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D015813:Substance Abuse Detection / Q000592:standards*; D019966:Substance-Related Disorders / Q000175:diagnosis*; D006113:United Kingdom; D014481:United States