Poster Number-34 - DRUG POSITIVITY AND TRENDS IN CLINICAL INQUIRIES FROM A NATIONAL DRUG MONITORING LABORATORY

DRUG POSITIVITY AND TRENDS IN CLINICAL INQUIRIES FROM A NATIONAL DRUG MONITORING LABORATORY

Purpose: The CDC Guideline for Prescribing Opioids recommends drug testing before starting opioid therapy, as well as consideration of drug testing at least annually during therapy. Clinical drug monitoring detects the presence of prescribed or illicit drugs or alcohol and has become an integral component of risk management when treating chronic pain and substance use disorders. When introducing drug monitoring into their practice clinicians often seek guidance regarding type and frequency of testing, as well as on the interpretation of (often complex) results. Clinician inquiries to our reference laboratory are triaged by dedicated drug monitoring client services representatives and escalated to subject matter experts in toxicology, pathology, or pharmacology as appropriate. We sought to characterize the frequency of test ordering and rates of positivity for drug testing as well as the volume and scope of inquiries requiring escalation to a subject matter expert. This data should be useful to clinicians when considering which drugs are most relevant to test for, as well as to provide educational support surrounding the most frequently asked questions drug monitoring.

Methods: To determine frequency of testing and drug positivity data, we analyzed de-identified quantitative, definitive urine drug tests (UDT) performed at Quest Diagnostics over a 12-month time frame from all categories of providers. UDT included either presumptive immunoassay screening tests with confirmation of positive results by quantitative definitive mass spectrometry, or direct quantitative definitive mass spectrometry. Mass-spectrometry methods were validated using National Institute of Standards and Technology (NIST)-traceable reference materials. Results were considered positive when a drug (or appropriate metabolite) was identified at a concentration equal to or greater than its cutoff. Tests were available as individual drugs or as part of predefined or custom panels. Not all specimens were tested for all drug classes as ordering patterns vary among clinicians. 

To evaluate the most frequently asked questions, all inquiries recorded for a 12-month time frame were reviewed. Only inquiries that were escalated to the Medical Advisor Team and resolved by a toxicologist, pathologist, or pharmacist were included in the analysis. Over 1,330 of these unique toxicology consultation records were identified. Inquiries were cataloged by drug class based on test code, test name, and free text associated with the interaction record. Free text fields containing inquiry and resolution information were sorted into categories based on subject matter.

Results: Over the 12-month study period, the tests most ordered (at least 90% of the time) by frequency were for the drugs/ classes: opiates, benzodiazepines, cocaine, amphetamines, and oxycodone. The highest positivity rates were for buprenorphine products presumably prescribed for opioid use disorder (43% with naloxone, 28% without), followed by marijuana (28%), gabapentin (22%), opiates (12%), benzodiazepine (12%), alcohol (11%), and fentanyl (11%).
Of the 1,330 inquiries, those most frequently escalated to subject matter experts regarded unexpected positive results (432; 32%). The next most common inquiry regarded an explanation of drug analytes and their metabolites (336; 25%). There were inquiries regarding correlation of the quantitative results of a drug test result to the dose of the drug taken (124; 9%), as well as whether drug results were consistent with new use versus terminal elimination following cessation (121; 9%). In order of decreasing frequency, the other categories of inquiries received included test selection, comparison of results obtained by different methods, unexpected negative results for a prescribed medication, interpretation of a result of “interference”, determination of therapeutic or toxic levels, and detection window of a substance.

When analyzed by drug class, inquiries regarding opioids were the most frequently escalated to a subject matter expert (446; 36%), with almost half of the opioid queries involving fentanyl. Amphetamine inquiries accounted for 10% of the inquiries, benzodiazepines 9%, buprenorphine 8%, marijuana 8%, alcohol 7%, and cocaine 4%.

Conclusion:

When analyzing test frequency, the most common urine drug tests ordered included opiates, benzodiazepines, cocaine, amphetamines, and oxycodone. From a positivity standpoint, samples for buprenorphine, opiates, marijuana, and gabapentin were positive at least 20% of the time. These specific tests were also among the most frequently asked questions posed to our toxicologists. Those drugs with a lower incidence of positivity (e.g., MDMA, Barbiturates, Mitragynine, PCP) required less consultation.
Utilizing drug positivity data in conjunction with frequency of testing and call-center data can provide clinicians with insights into what drugs/classes are most relevant to test for and which are most likely to be impacting their patients. These data may factor into test selection by clinicians as well as recommendations in drug monitoring guidelines.
 


References: Dowell D, Haegerich TM, Chou R. CDC Guideline for Prescribing Opioids for Chronic Pain- US, 2016. MMWR Recomm Rep 2016;65(No. RR-1):1–49.