Study provides new estimates of opioid misuse, addiction

New estimates suggest that 20 to 30 percent of opioid analgesic drugs prescribed for chronic pain are misused, while the rate of opioid addiction is approximately 10 percent, reports a study in the April issue of PAIN®, the official journal of the International Association for the Study of Pain. The journal is published by Wolters Kluwer.

"On average, misuse was documented in approximately one out of four or five patients and addiction in approximately one out of ten or eleven patients," who were prescribed opioids as part of their treatment for chronic pain, writes Kevin E. Vowles, PhD, of University of New Mexico (UNM), Albuquerque, and colleagues. The researchers note extremely wide variation in reported rates of misuse, abuse, and addiction and raise questions about the benefits of widespread opioid use for chronic pain, given the harmful consequences.

Study Provides New Estimates of Opioid Misuse and Addiction... Dr. Vowles and coauthors reviewed published studies to produce "updated and expanded" estimates of rates of problem opioid use. Prescribing of these powerful pain-relieving drugs has skyrocketed in the past 15 years. This sharp increase has coincided with an increase in opioid-related problems, such as dependence, withdrawal, and overdose. The study was funded by a grant from the Center for Health Policy at the Robert Wood Johnson Foundation Center for Health Policy at UNM.

Estimates were calculated using data from 38 reports, with adjustments for study sample size, quality, and methods. Three specific types of problem opioid use were recorded: misuse, abuse, and addiction. The study found very high variability in specific rates of opioid misuse and addiction identified across different studies--ranging from less than 1 percent to more than 80 percent.

On adjusted analysis, the average rate of opioid misuse was estimated at 21 to 29 percent. Misuse was defined as using opioids contrary to instructions, regardless of harmful or adverse effects.

Adjusted average rates of opioid addiction--defined as continued opioid use with actual or potential harmful effects--ranged from 8 to 12 percent. Only one study analyzed the rate of opioid abuse: intentionally using the drugs for nonmedical purposes.

...With Insights into "Clinical Reality'" of Opioids for Chronic Pain

Reported rates of opioid addiction were lower for studies with a "primary focus" on this issue. Otherwise, studies with different characteristics yielded comparable rates of problem opioid use.

Amid the ongoing "opioid epidemic," the new review provides informed estimates of specific types of problem opioid use. The researchers call for further research, including relevant information on patient and pain-related characteristics and focusing on specific types of problematic opioid use. Such studies are needed to provide accurate data for clinicians and policymakers to make sound decisions.

Dr. Vowles and colleagues draw special attention to the high rate of opioid misuse. They write, "If it is accurate that approximately one in four patients on opioids display patterns of opioid misuse, but not addiction, then perhaps more efficient targeting of treatment resources would be of benefit." For example, even low-intensity interventions, such as patient education and monitoring, might be a viable alternative to simply not prescribing the medications for those at risk of misuse.

The researchers also note that 35 of the 38 studies reviewed were conducted in the United States. This "curious finding...suggests that this issue is of both high interest and is perhaps a problem that is somehow uniquely relevant to the US," they write.

Dr. Vowles and coauthors discuss the documented rates of opioid misuse and addiction in light of the "clinical reality of chronic pain treatment." They conclude, "We are not certain that the benefits derived from opioids, which are rather unclear...compensate for this additional burden to patients and health-care systems."