Definitive Testing Detects Opioid Nonadherence

Patients prescribed an opioid should undergo definitive testing in addition to point-of-care testing, according to a study presented at the American Academy of Pain Medicine 31st Annual Meeting in National Harbor, Md.

Definitive testing revealed if patients prescribed an opioid were adhering to their medication or taking another medication that had not been prescribed, going beyond the information gathered from point-of-care testing.

The study included urine samples from 400,334 patients prescribed hydrocodone as their only opioid and 234,273 patients prescribed oxycodone as their only opioid. The researchers screened each sample for codeine, morphine, hydrocodone, norhydrocodone, hydromorphone, oxycodone, noroxycodone, and oxymorphone. If a sample tested positive for opioids, they underwent a mass spectrometry and were categorized into one of four groups:

• Positive for only the prescribed opioid
• Positive only for a non-prescribed opioid
• Positive for both the prescribed opioid and a non-prescribed opioid
• Negative for all opioids

First, the researchers tested the samples to see if they were positive for any opioids. If so, the samples went on to further definitive testing to pinpoint particular drugs.

For patients prescribed hydrocodone who tested positive for any opioid (n=318,287), 86.1% were positive for only the prescribed opioid, 2.7% for only a non-prescribed opioid, 6.2% for both a prescribed and non-prescribed opioid, and 5% were negative for all opioids.

Out of the 28,195 samples of patients prescribed hydrocodone that tested positive for other opioids, 21.7% were positive for codeine, 41.5% for morphine, 37.9% for oxycodone, 53.2% for oxymorphone, and 51.4% for noroxycodone.

For patients prescribed oxycodone who tested positive for any opioid (n=182,823), 87.7% were positive for only the prescribed opioid, 0.2% for only a non-prescribed opioid, 11.5% for both a prescribed and non-prescribed opioid, and 0.5% were negative for all opioids.

Out of the 21,461 samples of patients prescribed oxycodone that tested positive for other opioids, 11.3% were positive for codeine, 38.1% for morphine, 45.8% for hydrocodone, 49.0% for hydromorphone, and 57.0% for noroxycodone.

Patients who are not taking their medication or are taking medications they have not been prescribed require proper follow-up. The researchers believe that definitive testing can provide an objective way for physicians to identify these issues, thus allowing them to discuss the appropriate next steps for care.

All of the researchers in this study disclosed their status as employees of Ameritox Ltd. in Baltimore, Md.