Urine Drug Testing as an Evaluation of Risk
Since the mid-1990s, chronic opioid therapy (COT) for the treatment of non-cancer-related chronic pain has become an essential aspect of modern medical practice in many parts of the United States. At the same time, the diversion of opioid substances has increased precipitously.1 This likely is not a coincidence. Hydrocodone, for example, is the most widely prescribed opioid medication, with over 131 million prescriptions dispensed in 2006. Hydrocodone is also the most commonly identified opioid in forensic laboratories in which cases of overdose or drug-related death are investigated.2
Practitioners who prescribe COT are responsible for performing due diligence in identifying, monitoring, and managing risk factors as they determine which patients to treat. Practitioners need objective data, in addition to “gut instinct,” to determine whether their risk assessment techniques are reliable and valid. They need to know they are treating patients who have the ability and willingness to handle medications appropriately. One recent editorial opined that physicians must acquire basic knowledge of sub-stance abuse and become proficient in screening and assessing risk.3
A number of clinical techniques may be used to assess and reduce risk. Some practitioners require patients to bring their remaining pills in the original bottles to follow-up visits, so that the pills may be counted. Such pill counts provide simple, rapid identification of which patients are unable to appropriately manage the supply of medications with which they have been entrusted, though it cannot identify individuals who may hoard pills.3 Additionally, state prescription-monitoring program reports are also readily available in many states, allowing providers to identify which patients are “doctor shop-ping” for controlled substances.2
Urine drug testing (UDT) has become “an essential feature of pain management, as physicians seek to verify adherence to prescribed opioid regimens and to detect the use of illicit or unauthorized licit drugs.”4 A recent position paper by the American Pain Society on COT calls for UDT on high risk patients and for clinicians to consider UDT on patients who are not considered high risk or who have shown medication aberrant behaviors.5 Other authors argue for UDT to be done on all patients on COT.6 Some type of monitoring is essential for patients on COT and UDT is an increasingly important tool in this regard.
While some studies seek solely to identify the presence of illicit or unauthorized prescription substances, the absence of a prescribed opioid medication—hereafter described as an “unexpected negative” finding—also raises a variety of clinically relevant possibilities:
- patient never took the medication
- patient took the medication but was for some reason unable to absorb the medication
- patient took the medication but for some reason was unable to excrete the medication or its metabolites
- patient last took the medication too many hours before the test for a detectable level to be present
- patient lost the medication
- patient sold or otherwise illicitly distributed the medication
- medication was stolen
- any combination of possibilities
While UDT does not capture all aberrant behavior, it appears to be a good overall indicator of the effectiveness of risk assessment techniques. However, reliance on UDT to confirm adherence “…can be problematic if the results are not interpreted correctly, and evidence suggests that many physicians lack an adequate understanding of the complexities of UDT and the factors that can affect test results.”5 One study found that only 30% of the physicians surveyed could answer half of the questions offered about interpreting UDT findings correctly.7
UDT is still under-utilized by healthcare providers. One study of primary care physicians found that only 15% of physicians performed UDT on patients after opioids had been prescribed.8 UDT is administered based on the assumption that substances consumed, applied, injected, or smoked by patients will be excreted either in raw form or as predictable metabolites in the urine. Tests may vary with regard to sensitivity and specificity, but are generally able to detect the relatively recent use of specified substances above certain minimum concentrations, sometimes referred to as “cut-off” levels.
UDT and Risk Management
While healthcare providers who are treating patients with chronic pain should be administering UDT, questions are raised about what to expect on an aggregate basis. While each patient’s UDT can be judged and dealt with on a case-by-case basis, there is also the question of what the results are showing about the provider’s overall risk assessment and management methods. Risk assessment has become a standard of care for all providers of COT.5 If a provider is properly assessing risk, it stands to reason that the rate of inappropriate UDT results found in the overall practice patient population will be lower than it would be otherwise. While many factors are involved (patient population served, base rates of illicit drug use in the community, etc) the aggregate of UDT findings for a practice can be seen as a proxy for the success of one’s risk assessment and monitoring methods. Practices, however, rarely do a pre-post analysis when they implement new UDT processes, so interpretation of overall UDT results is problematic. One solution is to use pub-lished studies and their reported rates of inappropriate UDT results as a baseline for comparison. While practices vary widely, published rates of inappropriate UDT results offer one of the few available tools for interpretation and comparison of one’s own UDT findings.