Immunoassay-Based Drug Tests Are Inadequately Sensitive for Medication Compliance Monitoring in Patients Treated for Chronic Pain.

BACKGROUND: Enzyme immunoassays (EIA) have notable limitations for monitoring therapeutic compliance in pain management. Chromatography coupled with mass spectrometry provides definitive results and superior sensitivity and specificity over traditional EIA testing.
OBJECTIVE: To analyze and compare the sensitivity of EIA results together with known prescriptions to liquid chromatography-tandem mass spectrometry (LC-MS/MS) for monitoring drug use (and abuse) in patients treated for chronic pain. STUDY
DESIGN: A total of 530 urine samples from patients being treated for chronic pain were studied.
SETTING: Pain management clinic in the United States.
METHODS: The samples were tested for a profile of chronic pain medications and illicit drugs with commercially available EIA kits followed by analysis with Agilent LC-MS/MS system.
RESULTS: The EIAs exhibited poor sensitivity and high rates of false negative results in the pain management setting. For example, 21% of EIA for opiates show false negative results. Mass spectrometry methods were more sensitive, detected a broader range of drugs and metabolites, and could detect non-prescribed drug use and simulations in compliance. LIMITATIONS: Patients do not always accurately report drug use information, and some drugs do not have EIA methods available for comparative purposes.
CONCLUSIONS: Mass spectrometry is a more robust and reliable method for detection of drugs used in the pain management setting. Due to the extent of undisclosed use and abuse of medications and illicit drugs, LC-MS/MS testing is necessary for adequate and accurate drug detection. In addition, LC-MS/MS methods are superior in terms of sensitivity and number of compounds that can be screened, making this a better method for use in pain management. Key words: Pain management, enzyme immunoassays, mass spectrometry, urine drug testing, prescription status, compliance.