McMaster University

Michael G. DeGroote
National Pain Centre

Scope of Search

Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain

Cluster 1: Deciding to Initiate Opioid Therapy

R03. Recommendation Statement

No. Recommendation Keyword
R03 When using urine drug screening (UDS) to establish a baseline measure of risk or to monitor compliance, be aware of benefits and limitations, appropriate test ordering and interpretation, and have a plan to use results. (Grade C). Urine drug screening
  • R03. Discussion
  • R03. Summary of Peer-Reviewed Evidence

R03. Discussion

In the context of using opioids for treating CNCP, UDS can be used to as a tool for: 1) setting a baseline measure of substance use that may help assess risk for addiction, and 2) ongoing monitoring of the patient’s compliance with opioids prescribed. However, opinions regarding UDS utility vary.

1. Types of Urine Drug Screening (UDS)

1.1 Point-of-care Testing

For point-of-care (POC) testing, the urine sample is collected and tested at the physician’s office/clinic.

  • POC test kits are available for purchase; urine dipsticks are required.
  • Results are immediate, but it tends to be less sensitive and specific than laboratory tests.

1.2 Laboratory Testing

For laboratory testing, the urine sample is collected at physician’s office/clinic and sent to a laboratory for testing.

There are two types of laboratory tests: immunoassay and chromatography (see Appendix B-3 for a comparison and overview of detection time).

  • Province health plans vary in funding UDS; some provide immunoassays for classes of drugs (opioids, cocaine, benzodiazepines, cannabis) or one single drug at a time (e.g., oxycodone, methadone).
  • Immunoassay detects drugs for a longer time than chromatography (5–7 days compared to 1–2 days) but does not distinguish between different types of opioids and often misses semi-synthetic or synthetic opioids such as oxycodone or meperidine.
  • Chromatography is more expensive and requires specification of the drug(s) to be identified e.g., oxycodone, morphine, codeine, hydromorphone (alternatively can indicate: “full screen” or “broad spectrum screen”).

2. Clinical Usefulness of UDS

2.1 Baseline Measure of Risk

UDS can be helpful in establishing the reliability of a patient’s reported substance use. Some clinicians believe that UDS should be used routinely to establish baseline information regardless how well the patient is known to the prescriber. They believe a universal approach will eventually “de-stigmatize” UDS and increase prescriber confidence in using opioids. Other clinicians point out that UDS, whether point-of-care or laboratory-completed, is costly, not available in all parts of Canada, and that routine use adds an unnecessary burden to the system. These clinicians believe that UDS should be used selectively with patients who may be at risk for misuse.

2.2 Monitoring for Compliance

During an opioid trial or after a patient is established on LTOT, UDS can be useful in detecting unauthorized drug use, non-compliance, and diversion (Adams 2001, Brown 2006). There is evidence that urine drug screening reduces substance use in LTOT patients (Manchikanti 2004, Manchikanti 2006).

There is no compelling evidence to guide physicians on identifying CNCP patients who should have UDS or how often. In deciding whether to order a baseline UDS, and how often to use screening to monitor patients, consider:

  • patient’s risk for opioid misuse and addiction
  • aberrant drug-related behaviours
  • availability of UDS.

3. Conducting Urine Drug Screening

3.1 Prior to Ordering the Test

  • Take a detailed history of the patient’s medication use for the preceding 7 days.
  • Inform patients that the UDS is not meant to “catch” or punish patients but to improve the safety and effectiveness of LTOT.
  • Tell the patient what results are expected from appropriate opioid use and ask the patient if anything else might show up. (This gives the patient the opportunity to inform the prescriber about changes in their use of the prescribed drug or illicit drug use).
  • If using a treatment agreement, add the requirement of UDS to the treatment agreement (see Recommendation 5).

3.2 Sample Collection and Preventing Tampering

3.2.1 Sample Dilution

The most common and easiest form of tampering is diluting the urine sample with water. Supervised sample collection makes tampering more difficult, but is a costly use of staff time and patients may find it demeaning. Use supervision if the patient is known to have tampered with a sample.

3.2.2 Sample Temperature

The temperature of the sample can be used to detect tampering because water added to a sample usually varies from body temperature. Temperature-test strips can be used, but they are costly, and must be read within minutes because the sample cools rapidly.

3.2.3 Creatinine Level

A urine creatinine of less than 2–3 mmol/liter is non-physiologic and suggests dilution. Most laboratories can test creatinine level.

4. Interpreting Unexpected Results of UDS

UDS can assist clinical decision-making but should not be considered definitive. Two examples illustrate this: 1) a patient who is diverting prescribed opioids might take a small amount of the prescribed drug so the UDS will be positive; 2) for cocaine there is a relatively short window of detection, so binge cocaine use could be missed.

Table B-3.1 reviews some common unexpected results and provides a range of possible reasons and some potential actions. In some cases the physician may find it useful to review unexpected results with the laboratory or a physician experienced in interpreting UDS. Prescribers who are unfamiliar with using UDS should take steps to increase knowledge and skill by seeking out an appropriate educational resource or observership.

Table B-3.1 Interpreting Unexpected Results of Urine Drug Screens

  Unexpected Result Possible Explanations Actions for the Physician
1 UDS negative for prescribed opioid.
  • False negative.
  • Non-compliance.
  • Diversion.
  • Repeat test using chromatography; specify the drug of interest (e.g. oxycodone often missed by immunoassay).
  • Take a detailed history of the patient’s medication use for the preceding 7 days (e.g., could learn that patient ran out several days prior to test)
  • Ask patient if they’ve given the drug to others.
  • Monitor compliance with pill counts.
2 UDS positive for non-prescribed opioid or benzodiazepines.
  • False positive.
  • Patient acquired opioids from other sources (double-doctoring, "street").
  • Repeat UDS regularly.
  • Ask the patient if they accessed opioids from other sources.
  • Assess for opioid misuse/addiction (See Recommendation 12).
  • Review/revise treatment agreement
3 UDS positive for illicit drugs (e.g., cocaine, cannabis).
  • False positive.
  • Patient is occasional user or addicted to the illicit drug.
  • Cannabis is positive for patients taking dronabinol (Marinol®), THC:CBD (Sativex®) or using medical marijuana.
  • Repeat UDS regularly.
  • Assess for abuse/addiction and refer for addiction treatment as appropriate
  • Ask about medical prescription of dronabinol, THC:CBD or medical marijuana access program.
4 Urine creatinine is lower than 2-3 mmol/liter.
  • Patient added water to sample.
  • Repeat UDS
  • Consider supervised collection or temperature testing
  • Take a detailed history of the patient’s medication use for the preceding 7 days
  • Review/revise treatment agreement.
5 Urine sample is cold.
  • Delay in handling sample (urine cools within minutes).
  • Patient added water to sample.
  • Repeat UDS, consider supervised collection or temperature testing
  • Take a detailed history of the patient’s medication use for the preceding 7 days
  • Review/revise treatment agreement.

R03. Summary of Peer-Reviewed Evidence

1. Urine drug screening and other forms of adherence monitoring may reduce rates of substance abuse.

Urine drug screens are an important but underutilized therapeutic tool. Currently, only a small percentage of physicians prescribing opioids for pain are utilizing UDS as a clinical tool: in one study only 8% of physicians utilized UDS (Adams 2001). Another study found only 7% used UDS before initiating opioids and 15% used UDS once patients were on long-term treatment (Bhamb 2006).

Yet, UDS can have value in both detecting substance abuse and in reducing it. In one study (Manchikanti 2004) of patients on stable doses of opioids, 16% were found to have evidence of illicit drug use, and the use of random UDS was found to decrease the amount of illicit drug use. Another evaluation of the same group of patients (Manchikanti 2006) found that a combination of UDS, treatment agreements, pill counts, and education reduced substance abuse by 50%.