Clinicians' perspective on the use of immunoassay versus definitive laboratory quantitation methodologies for medication monitoring

Treating chronic pain is complicated. Primary care doctors and others are called on to treat the vast majority of patients with pain, to do so in brief visits and to do it safely. This is a tall order, but it is possible to do it well when the proper tools are employed to aid the clinician in diagnosing and monitoring the patient. Among these tools, the one that has been most useful is urine drug testing. Prescribers can perform presumptive screens with the immunoassay method in my office, but this method has limitations in accuracy and specificity and sensitivity. When medically necessary, it makes sense to seek definitive testing from the laboratory to confirm results of immunoassay tests with chromatographic testing and/or when there is the possibility of a false negative in the office. These "false negatives" are extremely common, with patients using nonprescribed opioids and illicit medications often go undetected if one were to stop at the office-based result. These patients are in danger of addiction and overdose, and this added information is crucial in efforts to treat pain and avoid these complications.