title: Detection of phosphatidylethanol (PEth) in the blood of drivers in an alcohol ignition interlock program.
abstract: OBJECTIVE
  The rate of failed interlock blood alcohol content (BAC) tests is a strong predictor of recidivism post-interlock and a partial proxy for alcohol use. Alcohol biomarkers measured at the start of an interlock program are known to correlate well with rates of failed BAC tests over months of interlock use. This study evaluates 2 methods of measuring low blood levels of the biomarker phosphatidylethanol (PEth). PEth is a 100 percent alcohol-specific biomarker and strongly intercorrelated with several independent indicators of drinking driving risk, including 8 other biomarkers, 3 psychometric assessments, and the rate of failed interlock BAC tests during many months of interlock use. Does a more sensitive method of measuring PEth at program entry detect drinking even among those who subsequently log no failed interlock tests?
  
  
  METHODS
  In a sample of 281 driver blood samples, PEth was measured by both high-performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LCMSMS) in order to compare sensitivity and accuracy. The average rate of failed interlock BAC tests was the criterion measure for marker sensitivity. LCMSMS, calibrated to detect low levels of drinking as a possible measure of abstinence violation, was judged relative to the standard HPLC assay for PEth measured up to 4 μmol/L.
  
  
  RESULTS
  The 2 methods showed a good quantitative relationship (r(2)> .86). LCMSMS detected positive PEth levels in samples that were below the limit of detection of the HPLC method. PEth measured by LCMSMS was positive for a higher proportion of driving under the influence (DUI) offenders who logged zero failed interlock BAC tests than were detected by HPLC.
  
  
  CONCLUSIONS
  Although HPLC is the widely used standard for measuring PEth in clinical alcoholism samples, the LCMSMS method, when calibrated to detect trace amounts of the major component of PEth, can detect abstinence levels of alcohol near zero intake and still correlate strongly with other indicators related to alcohol use and road safety.
authors.affiliation: Pacific Institute for Research and Evaluation, Impaired Driving Center, Calverton, Maryland 20705-3111, USA. Marques@pire.org
authors.forename: Paul
authors.initials: P
authors.lastname: Marques
authors.forename: Therese
authors.initials: T
authors.lastname: Hansson
authors.forename: Anders
authors.initials: A
authors.lastname: Isaksson
authors.forename: Lisa
authors.initials: L
authors.lastname: Walther
authors.forename: Joseph
authors.initials: J
authors.lastname: Jones
authors.forename: Douglas
authors.initials: D
authors.lastname: Lewis
authors.forename: Mary
authors.initials: M
authors.lastname: Jones
mesh_terms: D000428:Alcohol Drinking / Q000097:blood*; D001334:Automobile Driving / Q000706:statistics & numerical data; D015415:Biomarkers / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D020404:Glycerophospholipids / Q000097:blood*; D006801:Humans; D011482:Protective Devices; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D015415:Biomarkers; D020404:Glycerophospholipids; C051521:phosphatidylethanol