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Study: Half of American Adults Misuse Their Prescription Drugs

Growing percentage of patients combine drugs without physician’s knowledge

Most American adults taking opioids and other commonly prescribed medications use them in ways that put their health at risk, including potentially dangerous combinations with other drugs, according to a new study from Quest Diagnostics.

The multiyear analysis of more than three million test results showed that 54% of patients tested in 2015 had evidence of drug misuse, slightly above the 53% misuse rate in 2014. While high, the misuse rate declined 14% from 63% in 2011. The study was based on results from patients tested in 49 states and the District of Columbia between 2011 and 2015.

Drug misuse is defined as evidence, based on laboratory test results, that a patient is using or combining nonprescribed drugs or skipping doses in a manner that is inconsistent with the ordering physician’s directions. Quest’s prescription drug-monitoring test services help identify evidence of the use of up to 44 commonly misused prescription and illicit drugs, such as opioids, amphetamines, sedatives, marijuana, and heroin.

The analysis also found that among patients whose test results showed evidence of prescription drug misuse, the percentage of those who combined their prescription medication with other drugs not known to the physician jumped sharply in recent years. In 2015, 45% of these patients had test results that showed evidence of one or more other drug(s) in addition to their prescribed drug(s). This compares with 35% in both 2014 and 2013; 33% in 2012; and 32% in 2011.

The findings are significant because combinations of certain drugs, such as opioids and sedatives, can result in potentially dangerous adverse effects, including severe respiratory depression, coma, and death.

“For some patients, opioids and sedatives are co-prescribed, which is of concern. The discovery that a growing percentage of people are combining drugs without their physician's knowledge is deeply troubling given the dangers. Perhaps patients do not understand that mixing even small doses of certain drugs is hazardous, or they mistakenly believe prescription medications are somehow safe,” said co-researcher F. Leland McClure III, PhD, Medical Affairs Director at Quest Diagnostics.

Approximately 1.6% of patients tested for heroin showed evidence of heroin use. Heroin use was detected across all age ranges in adults tested, including those over the age 65 of years, although it was most likely to be detected in patients 25 to 34 years of age (3.6% among those tested) and in patients 18 to 24 years of age (3.2%). Men were tested for heroin less often than women but had a positivity rate more than 50% higher than that of women (1.97% versus 1.26%, respectively).

The researchers also found that nearly one in three patients (28.6%) who used heroin combined it with benzodiazepines, a class of prescription psychoactive medications that includes tranquilizers, such as Xanax and Valium. In 92% of these patients, the benzodiazepines were not prescribed by a physician, meaning the patients were using an illicit combination of heroin and benzodiazepines.

Benzodiazepines can have strong sedative effects, including respiratory depression, when combined with alcohol, other sedatives, or illicit drugs, such as heroin. Data from the National Institute on Drug Abuse show that there was a fivefold increase in the number of deaths related to benzodiazepines between 2001 and 2014.

In March 2016, the Centers for Disease Control and Prevention issued guidelines recommending that clinicians consider opioid therapy only if the expected benefits for both pain and function are anticipated to outweigh the risks to the patient, and that health care providers perform drug tests on their patients before starting (baseline) and periodically during opioid drug therapy as “urine drug tests can provide information about drug use that is not reported by the patient.”

The new study’s limitations include geographic disparities; the inability to confirm drug misuse through access to medical records or clinical evaluations; and technical factors and patient variations, such as drug metabolism and the patient’s hydration state, that may have affected the reliability of a minority of results. Quest Diagnostics does not provide services to all clinicians in the U.S., so the results are not broadly representative of all patients taking prescription medications in this country. It is also possible that some clinicians tested patients because of appropriate suspicions of drug misuse, and that some clinicians omitted to specify all of the drugs prescribed for the patient on a test order, skewing some results.

Source: PR Newswire; July 26, 2016; and Quest Diagnostics Report; June 2016.

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