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*Pain Trials Center, Brigham and Womens Hospital, Boston, Massachusetts;
Departments of
Anesthesiology and
Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; and
Pain Management Center, Brigham and Womens Hospital, Boston, Massachusetts
Address correspondence to Gilbert J. Fanciullo, MD, MS, Pain Management Center, Dartmouth-Hitchcock Medical Center, One Medical Center Dr., Lebanon, NH 03756. Address e-mail to Gilbert.J.Fanciullo{at}Hitchcock.org Reprints will not be available from the authors.
| Abstract |
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IMPLICATIONS: Monitoring both urine toxicology and aberrant behavior in chronic-pain patients treated with opioids identified more problem patients than by monitoring either alone. The authors recommend routine urine testing on all patients prescribed opioids for noncancer pain and as a required element in all opioid analgesic studies.
| Introduction |
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The doctor-patient relationship is traditionally based on the physician accepting the veracity of patient self-report. Many physicians monitor opioid therapy solely by patient self-report and by observing patients for addictive behavior. Unfortunately, patient care in the chronic pain setting is hampered by pervasive inaccuracies in patient self-report of drug use. Patients with chronic pain tend to underestimate their medication use (6). Chronic-pain patients regularly provide incorrect information on illicit drug use (7), which may be revealed by urine toxicology screens. The use of urine toxicology screens to supplement patient self-report is standard in the drug-abuse treatment setting (8). Opioid contracts in pain management centers usually require that patients submit to urine toxicology screens (9), but the only study that reviewed the effect of a signed contract on patient compliance found that there was no effect (5). We performed this study to describe the results of regular urine toxicology screens performed on all patients maintained on opioid therapy by the authors for chronic pain in two university pain centers, in comparison to monitoring for addictive behaviors.
| Methods |
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Urine testing was performed in a two-step process. Initial screening was an enzyme-mediated immunoassay test that detected the following drugs: amphetamines, analgesics, anticonvulsants, antihistamines, barbiturates, benzodiazepines, cocaine metabolites, marijuana (tetrahydrocannabinol), methadone, opiates, phenothiazines, tricyclics, and volatiles (includes ethanol). All specimens were also sent for a gas chromatography/mass spectroscopy analytical method, which is a highly specific and sensitive test used to identify individual opioids. A patient was considered to have a "positive urine toxicology" if one or more of the following was identified in the urine sample: an illicit drug, a nonprescribed controlled drug, or ethanol. A patient who tested positive for one or more substances was categorized as having a single positive toxicology. Absence in the urine of the prescribed opioid was not considered a positive test.
Medical records were retrospectively reviewed by four of the authors (JV, SS, RJR, and GJF) for demographic information, drug-taking behaviors, and urine toxicology reports. Patients were screened for five selected behaviors that have been described as being suggestive of inappropriate drug-taking behaviors (5,10). These behaviors were reports of lost or stolen prescriptions, consumption in excess of prescribed dosage, visits without appointments, multiple drug intolerances and allergies, and frequent telephone calls. Patients who had one or more of these behavioral "issues" were categorized as having "behavioral issues."
Demographic features were tabulated descriptively. Descriptive statistics were used to describe the proportion of patients with positive urine toxicology screens and behavioral issues. Standard nonparametric tests were used for univariate comparisons. Logistic regression was used to model the effects of age, sex, and issues on urine toxicology. Goodness of fit was assessed by using diagnostic plots, changes in deviance, and the inclusion of interaction terms. A P value <0.05 was used to indicate statistical significance, and no adjustments were made for multiple comparisons. Ninety-five percent confidence intervals are reported.
| Results |
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Fifteen percent (n = 18) of all patients had 1 behavioral issue, 5% (n = 6) had 2 issues, and 3% (n = 3) had 3 issues. Of the patients with one behavioral issue, the most prevalent was consumption in excess of the prescribed dosage, which occurred in 56% (n = 10) of this subgroup. Patients with at least one issue were 1.35 times more likely to have a positive toxicology screen (95% confidence interval, 0.752.44) (Fig. 1).
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| Discussion |
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Extrapolating from other populations in an attempt to define a population baseline for marijuana use among chronic-pain patients is difficult. There are no prior reports of prevalence of marijuana use validated by urine testing in patients with chronic pain. A recent study showed that 4.3% of commercial tractor-trailer drivers tested positive for marijuana (14). This figure does not include the 19% of drivers who refused to supply an anonymous sample. Five percent of "low average risk" and 17% of "high average risk" adolescents tested positive in another study (15). Before September 11, 2001, 4.4% of a sample of adult residents of Manhattan, NY, anonymously reported marijuana use, compared with 5.7% after September 11; the increased use was presumably related to stress (16). Twenty of 122 patients in this report had urine toxicology reports demonstrating the presence of marijuana. This prevalence of 16.4% seems to be more closely allied with the "high average risk" adolescent group than with a more normal population sample.
The long-term use of opioids for chronic noncancer pain is growing exponentially in the United States, particularly in the primary care setting. The increased willingness to prescribe opioids derives from a number of scientific, political, and cultural influences. These include scores of outcome studies in cancer and in acute pain suggesting safety and efficacy (17), a few outcome studies in chronic noncancer pain (10), regulatory imperatives to relieve pain (18), and the imperative to provide pain relief implicit in the discussion of euthanasia (19).
However, many physicians remain unconvinced of the safety of long-term opioid treatment in noncancer pain, mainly because of fears of addiction and tolerance (2). Physicians generally judge whether their treatment is conferring benefit or harm by patient self-report, physical examinations, and laboratory tests. Unfortunately, each of these methods has serious inadequacies in determining the effect of opioids on chronic pain. Patient self-report of medication and drug use is unreliable (6,7), and neither physical examinations nor laboratory tests can measure pain or its relief (20). Patients may report inaccurately despite appropriate intentions or may actively seek to deceive for a variety of reasons (21,22). The published literature does little to reassure about the safety of opioids vis-à-vis addiction, because no published prospective outcome study has incorporated any specific definition of addiction or method of measuring addiction. Published guidelines on the use of opioids for chronic noncancer pain all agree that close patient monitoring for benefits and harm is important (23). Unfortunately, specific methods for monitoring patients for harm from opioids have not been validated.
The question arises: why is it important to recognize illicit or nonprescribed drug use in our chronic-pain patients being treated with opioids? It is important because our patients may suffer from the disease of addiction, and we may not have other means of making this important diagnosis. The diagnosis is important because treatment for addiction is possible and because we harm our patients by not identifying this disease and implementing the proper treatment. We harm our patients by prescribing opioids to them when they may need detoxification from opioids, inpatient drug treatment, and continuing treatment for their addiction.
Our patients may be diverting the drugs we prescribe to an illegal market, and by failing to identify patients who may be diverting opioids, we may be contributing to the sustenance of an underground criminal subculture. We may also be unintentionally responsible for opioid overdoses and deaths and for the possible addiction of persons who acquire these drugs illegally (24). Our patients may have a pseudoaddiction, or they may be self-medicating an unidentified anxiety disorder, bipolar disorder, or posttraumatic stress disorder, and identifying a marker, such as inconsistent urine toxicology results, may stimulate the provider to delve more deeply into the patients problems.
It is at least equally as important and perhaps more important to include urine toxicology testing because it helps to validate and destigmatize (25) our patients with consistent urine results, with or without aberrant behaviors that have been poorly correlated or not correlated at all with the above conditions.
In this study, 43% (n = 53) of 122 patients receiving long-term opioid therapy for chronic nonmalignant pain had a "problem," defined as the presence of either a positive urine toxicology screen or at least one behavioral issue. Positive urine toxicology was defined as ethanol, an illicit drug, or a nonprescribed controlled drug. The behavioral issues we chose to monitor, based on previous work (5), were reports of lost or stolen prescriptions, consumption in excess of prescribed dosage, visits without appointments, multiple drug intolerances and allergies, and frequent telephone calls. We found that monitoring of urine toxicology was more effective at identifying problem patients (as we defined it) than monitoring behaviors alone and that monitoring behaviors alone would have resulted in missing approximately half of the patients with problems. An increased probability of positive urine toxicology with an increasing number of inappropriate behaviors supported the internal validity of this process. We chose not to label urine devoid of the prescribed opioid as a "positive" test, because of concerns about the accuracy of existing tests in detecting therapeutic concentrations of several commonly prescribed opioids.
Urine toxicology screening has an important potential role in the management of patients receiving chronic opioid therapy and is already standard in the addiction treatment setting (26,27). The relatively large proportion of patients in our sample with urine toxicology results divergent from their implied self-report suggests that self-report of compliance alone is an insufficient screening tool and that safety monitoring would be enhanced by routine urine toxicology screening. Furthermore, because the presence of behavioral issues did not predict urine toxicology results, our data do not support monitoring only patients selected on the basis of aberrant behaviors. Instead, our results suggest that all patients receiving long-term opioid treatment for noncancer pain should be monitored with urine toxicology testing.
Our results also question the validity of previous studies on the safety of long-term opioid therapy related to addiction, which have monitored patients for addiction solely on the basis of unspecified aberrant drug-taking behaviors (3,5,2830). In this study, 72% (26 of 36) of patients with positive urine toxicology screens indicative of potential addiction or diversion did not evidence any of the behaviors thought to be useful screening tests for these disorders. This finding should lead to a reappraisal of previous research studies as perhaps less reassuring than previously thought.
Patients in this study were aware that urine toxicology screens would be obtained on most visits and had ample opportunity to appear compliant with their contracts by avoiding intake of inappropriate drugs for a few days or weeks before their visit, yet they did not do so. It is possible that the problems identified in this study represent a significant underestimate of inappropriate drug-taking behavior compared with what would be seen with more frequent testing.
There are many limitations to this study. The major limitation is that there is no accepted definition for addiction in the setting of opioid use for chronic pain (31). The predictive value of any screening test, such as urine toxicology or behavioral screening for addiction, can be assessed only in comparison to a "gold standard" diagnostic test, which does not exist for addiction in the setting of chronic pain. In fact, there are multiple syndromes of concern that complicate opioid therapy (e.g., addiction, diversion, pseudoaddiction, and self-medication for psychological symptoms), which are quite different and which may well require different diagnostic approaches. It is therefore not possible to know the diagnostic value of either positive urine testing or our behavioral issues. For example, it is not possible to know whether a positive screen for marijuana represents a problem with the patients analgesic regimen or whether a period of frequent telephone calls represents a problem with the patient or the clinic. It is also likely that somewhat different results would have been obtained with a different set of behavioral issues. Additional limitations include the retrospective nature of the study, the variability of monitoring regimens across centers and patients, and the limited sample size.
In conclusion, our patients receiving opioid therapy in two university pain management centers showed a significant prevalence of noncompliance with regard to consumption of nonprescribed medication and illicit substance use. A significant number of patients had positive urine toxicology screens in the absence of obvious aberrant drug-taking behavior. This study highlights the limitations of previous clinical trials and drug development programs that address the addiction risk of opioids. We recommend routine urine toxicology screens in the clinical management of all patients receiving opioid therapy and in clinical trials of opioids for chronic pain. Further research is needed to better define addiction and related complications of opioid therapy, to develop diagnostic procedures for these disorders.
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