title: An evaluation of the diagnostic accuracy of liquid chromatography-tandem mass spectrometry versus immunoassay drug testing in pain patients.
abstract: BACKGROUND
  Immunoassay screening is used by pain physicians to determine compliance with controlled substances. Because clinical use of pain medications is different from illicit drug use, there is a need to evaluate the level of diagnostic accuracy of this procedure for the pain patient.
  
  
  OBJECTIVE
  To compare the results of automated screening by immunoassay with analysis by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) in identifying pain patients using illicit drugs and pain patients excreting low concentrations of their prescribed medications.
  
  
  METHODS
  A diagnostic accuracy study.
  
  
  METHODS
  Urine samples from 4,200 pain patients were tested by immunoassay and LC-MS/MS for the following drugs and metabolites: Amphetamine, Methamphetamine, Alpha-hydroxyalprazolam, Lorazepam, Nordiazepam, Oxazepam, Temazepam, Cannabinoids, Cocaine, Methadone, Methadone Metabolite, Codeine, Hydrocodone, Hydromorphone, Morphine, Propoxyphene, and Norpropoxyphene.
  
  
  RESULTS
  In a number of patients negative immunoassay findings were superseded by positive results on analysis by Mass Spectrometry. These were termed false negative results. The greatest failures were for the benzodiazepines (28%) and for cocaine (50%).
  
  
  CONCLUSIONS
  The study was limited by the lack of complete demographics for the cohort and because only one immunoassay diagnostic product was used. It was also limited because not all drugs react the same in the immunoassay.
  
  
  CONCLUSIONS
  We show that in general, immunoassay screening results are accurate, although as shown in this study there are many false negative observations. The use of LC-MS/MS technology significantly decreases the number of false negative results.
authors.affiliation: Millennium Laboratories Research Institute, San Diego, CA 92127, USA.
authors.forename: Amadeo
authors.initials: A
authors.lastname: Pesce
authors.forename: Murray
authors.initials: M
authors.lastname: Rosenthal
authors.forename: Robert
authors.initials: R
authors.lastname: West
authors.forename: Cameron
authors.initials: C
authors.lastname: West
authors.forename: Bridgit
authors.initials: B
authors.lastname: Crews
authors.forename: Charles
authors.initials: C
authors.lastname: Mikel
authors.forename: Perla
authors.initials: P
authors.lastname: Almazan
authors.forename: Sergey
authors.initials: S
authors.lastname: Latyshev
mesh_terms: D001331:Automation; D001569:Benzodiazepines / Q000652:urine; D002853:Chromatography, Liquid; D003042:Cocaine / Q000652:urine; D015331:Cohort Studies; D005188:False Negative Reactions; D006801:Humans; D013287:Illicit Drugs / Q000652:urine*; D007118:Immunoassay / Q000592:standards; D055118:Medication Adherence; D009994:Osmolar Concentration; D010146:Pain / Q000188:drug therapy*; D016037:Single-Blind Method; D015813:Substance Abuse Detection / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000592:standards
chemical_list: D013287:Illicit Drugs; D001569:Benzodiazepines; D003042:Cocaine