High Frequency of Opioid Use Disorders Found in Patients Receiving Opioid Therapy

August 6, 2007 — Frequency of opioid use disorders in patients receiving opioid therapy from their primary care clinician is 4 times higher than that in the general population, according to the results of a large cohort study published in the July issue of The Journal of Pain.
"One of the primary treatment modalities for... chronic pain conditions is long-term opioid therapy," write Michael F. Fleming, MD, from the University of Wisconsin in Madison, and colleagues. "However, with the widespread reported abuse and diversion of OxyContin (Purdue Pharma L.P., Stamford, CT) and other opioids, there is increasing concern of opioid use disorders. Despite this concern, there is limited epidemiologic information on the rate of 'substance use disorders' and 'opioid use disorders' in persons who receive long-term opioid therapy from their primary care physician."
The objectives of this study were to evaluate the prevalence of substance use disorders in a sample of patients receiving opioid therapy from their primary care clinician and to examine the relationship among positive urine screening results, aberrant drug behaviors, and opioid use disorders.
From the primary care practices of 235 family physicians and internists employed at 6 healthcare systems in Wisconsin, the investigators recruited 801 adults receiving daily opioid therapy. The most common diagnoses for which these patients were receiving opioids for pain relief were degenerative arthritis, low back pain, migraine headaches, neuropathy, and fibromyalgia.
Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), criteria were used to diagnose substance abuse and/or dependence as well as opioid use disorder in the past 30 days. The point prevalence of current substance abuse and/or dependence was 9.7% (n = 78), and the point prevalence of current opioid use disorder was 3.8%. This prevalence was 4 times higher than that in general population samples (3.8% vs 0.9%).
Based on a logistic regression model, factors associated with current substance use disorders were age 18 to 30 years (odds ratio [OR], 6.17; 95% confidence interval [CI], 1.99 - 19.12), severity of lifetime psychiatric disorders (OR, 6.17; 95% CI, 1.99 - 19.12), having a toxicology test positive for cocaine (OR, 5.92; 95% CI, 2.60 - 13.50) or marijuana (OR, 3.52; 95% CI, 1.85 - 6.73), and the presence of 4 aberrant drug behaviors (OR, 11.48; 95% CI, 6.13 - 21.48).
Aberrant drug behaviors (self-sedation, using opioids for reasons other than pain, increasing the dose without authorization, and having felt intoxicated when using opioids) was the only variable included in the final model for opioid use disorders (OR, 48.27; 95% CI, 13.63 - 171.04), because in comparison, the other variables were not of independent significance.
The rate of toxicology tests positive for illicit drug use was 24%. Other noteworthy findings of this study include significant underreporting of drug use during the research interview. Even when they were guaranteed anonymity, 46% of patients with positive toxicology test results denied illicit drug use.
"The primary finding of this study is that the frequency of opioid use disorders is four times higher than reported in general population samples (3.8% vs 0.9%)," the authors write. "Although the frequency is low, about 1 case for every 25 patients on opioid therapy, it is of concern."
Study limitations include cross-sectional design precluding causal inferences, lack of prospective data, lack of information before patients were given opioids, lack of corroborative reports by family members and friends, possible underreporting of drug use, and selection bias.
"The addiction and pain medicine fields need to develop DSM-IV–like criteria for patients taking opioids for chronic pain," the authors conclude. "These criteria probably need to include aberrant drug behaviors but exclude normal pharmacologic properties of opioids such as tolerance and physical dependence. Once these criteria are accepted, we can develop and standardize the diagnosis of opioid addiction in persons reporting chronic pain."
The National Institute on Drug Abuse supported this study. None of the authors have disclosed receiving consultation fees or having investments in pharmaceutical companies.
J Pain. 2007;8:573-582.