Urine drug testing (UDT) is considered one of the mainstays of adherence monitoring in conjunction with prescription monitoring programs and other screening tools; however, UDT is associated with multiple limitations secondary to potential pitfalls related to drug metabolism, reliability of the tests, and the knowledge of the pain physician.1 The practice of UDT is more common in a noncancer pain setting than in an oncology or primary care setting; however, it may be utilized in a punitive manner in efforts to “catch” the patient with an inappropriate positive or negative screen result. Unfortunately, this often results in dismissal of the patient from the practice. Drug testing is most commonly used for two reasons: to identify substances that should not be present in the urine (forensic testing) and to detect the presence of prescribed medications (compliance testing).
URINE DRUG TESTING IN CHRONIC PAIN PATIENTS ON CHRONIC OPIOID THERAPY
The use of UDT to monitor patients on chronic opioid therapy (COT) treated in a pain clinic is reasonable; however, this testing is not mandatory for all patients on COT in all settings. The use of UDT should be based on the clinical judgment of the prescribing clinician; however, some clinicians and/or clinics test all patients on COT sporadically based on policy. Katz and Fanciullo2 propose that although further research is needed, it may be easier and more uniform to conduct routine urine toxicology testing in all patients with chronic pain treated with opioids. By adopting a uniform policy of testing, stigma is reduced while ensuring that those persons dually diagnosed with pain and substance use disorders receive optimal care. With careful explanation of the purpose of testing, patient concerns can be easily addressed.3,4
Abnormal UDT results of patients on COT in a chronic pain clinic generally include absence of the prescribed opioid, presence of nonprescribed drugs, presence of illegal drugs, and adulterated urine specimens.5
Fishbain and colleagues gathered urine toxicology results among 122 patients who were prescribed opioids for noncancer pain and found abnormal results in 43% of this sample.6 Michna and colleagues published a report on 226 patients primarily with chronic back pain and found 46.5% of the sample to have abnormal urine toxicology.5 In a retrospective study of 470 patients, 4 of 10 patients prescribed opioids also had abnormal urine toxicology.2 In 2003, Katz and colleagues reported that approximately 20% of patients with persistent pain on COT who seem compliant will test positive for an illicit drug and/or another non-prescribed opioid.7 Cone et al. analyzed a large number (n = 10,922) of urine samples from patients with persistent pain on COT and found that the overall prevalence of illicit drug use was 10.9%.8 The illicit drugs found in the urine of these patients most often were marijuana, cocaine, and ecstasy-related drugs.8 Couto and colleagues reported that over ...