How accurate are point-of-care urine drug screens in patients taking chronic opioid therapy?
EVIDENCE-BASED ANSWER:
In adults treated with opioids for chronic pain, point-of-care (POC) urine drug screens (immunoassays) for detecting opioids show a false-negative rate of 1.9%, a sensitivity of 92%, and a specificity of 93% compared with the gold-standard liquid chromatography tandem mass spectrometry (LC-MS). Oxycodone has the highest rate of false-negative results at 25%; methadone has the lowest rate at 4% to 6% (strength of recommendation [SOR]: A, 2 blinded diagnostic accuracy studies with similar results).
Of the 3414 samples submitted for opiate testing, 2191 tested positive using immunoassay and 2233 tested positive using LC-MS for a total of 42 false-negative results with immunoassay. The positive rate (percentage of samples testing positive by LC-MS) was 65%, and the false-negative rate was 1.9%. Methadone testing produced 17 false-negative results; the positive rate was 10%, and the false-negative rate was 6.1%. The immunoassay false-positive results occurred in patients taking hydromorphone and hydrocodone.
The study was limited by lack of demographic information on the participants.
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