Interpretation and utility of drug of abuse immunoassays: lessons from laboratory drug testing surveys.
BACKGROUND
To assist with patient diagnosis and management, physicians from pain services, drug treatment programs, and the emergency department frequently request that urine be tested for drugs of abuse. However, urine immunoassays for drugs of abuse have limitations.


OBJECTIVE
To use data from the College of American Pathologists Proficiency Testing Surveys to determine and summarize the characteristics, performance, and limitations of urine immunoassays for drugs of abuse.


METHODS
Six years of urine drug testing proficiency surveys were reviewed.


RESULTS
Lysergic acid diethylamide and methaqualone are infrequently prescribed or abused and, therefore, testing may be unnecessary. However, implementation of more specific testing for methylenedioxymethamphetamine and oxycodone may be warranted. Each drug of abuse immunoassay exhibits a different cross-reactivity profile. Depending on the cross-reactivity profile, patients with clinically insignificant concentrations of drugs may have false-positive results, and patients with clinically significant concentrations of drugs may have false-negative results.


CONCLUSIONS
Laboratory directors should be aware of the characteristics of their laboratories' assays and should communicate these characteristics to physicians so that qualitative results can be interpreted more accurately. Furthermore, manufacturer's claims should be interpreted with caution and should be verified in each organization's patient population, if possible.
Melanson
Stacy E F
SE
Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. semelanson@partners.org
Baskin
Leland
L
Magnani
Barbarajean
B
Kwong
Tai C
TC
Dizon
Annabel
A
Wu
Alan H B
AH
D003625:Data Collection; D006801:Humans; D007118:Immunoassay / Q000592:standards*; D007753:Laboratories / Q000592:standards*; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000652:urine; D010098:Oxycodone / Q000652:urine; D015813:Substance Abuse Detection / Q000379:methods / Q000592:standards*
D010098:Oxycodone; D018817:N-Methyl-3,4-methylenedioxyamphetamine