Friday, August 23, 2013

Does Pain Reliever Misuse Lead to Heroin?

A new report from the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) shows that persons aged 12 to 49 who had used pain relievers non-medically were 19 times more likely to have initiated heroin use within the past 12 months than others in that age group (0.39% vs 0.02%). The report is surprisingly vague as to what pain relievers are of greatest concern, but it might be surmised that opioid analgesics are frequently implicated.

The report further shows that 4 out of 5 recent heroin initiates (79.5%) had previously used prescription pain relievers non-medically. Released in August 2013 and titled “Associations of Nonmedical Pain Reliever Use and Initiation of Heroin Use in the United States” [available here], the report is based on data from SAMHSA’s National Survey on Drug Use and Health (NSDUH), covering the period of 2002 to 2011. NSDUH is a national survey of over 67,500 people aged ≥12.

In a press release [here], SAMHSA notes that, while the report shows that people using prescription pain relievers non-medically were at greater risk of later starting heroin, it also demonstrates that the vast majority of Rx-pain reliever misusers did not start using heroin. In fact, only 3.6% of all persons using the analgesics non-medically went on to use heroin within 5 years.

One objective of the report was to identify some of the factors behind the rise in the rates of heroin use, dependence (ie, addiction), and initiation that have occurred in the U.S. The number of people reporting that they have used heroin in the past 12 months rose from 373,000 in 2007 to 620,000 in 2011. Similarly, the number of persons addicted to heroin in the past 12 months climbed from 179,000 in 2007 to 369,000 in 2011. During that same period, the number of people using heroin for the first time in the past 12 months increased from 106,000 to 178,000.

Past-year heroin initiation rates went up sharply in all U.S. regions except the South, where the rate stayed lowest in country. Heroin initiation rates were also lower among Blacks than among other racial and ethnic groups.

We have noted in previous UPDATES [eg, here] that, for various reasons, increasing numbers of misusers of opioid analgesics have turned to heroin and this has been of much concern. However, data in this SAMHSA report suggest that, overall, relatively tiny proportions of persons misusing pain relievers (<0.4%) go on to use heroin — and, it should not be presumed that such misusers are persons with pain.

Of greatest importance, the NSDUH survey defines non-medical use of prescription drugs as “use of drugs that were not prescribed for the respondent or used only for the experience of feeling they caused.” So, persons broadly classified as non-medical users could include persons with pain who actually used the analgesics, perhaps shared by friends or family members, for medical reasons. For example, prior studies have distorted the misuse of drugs among teenagers in this regard [see UPDATE here].

The report authors concede that there are many plausible explanations for their findings. For example, they suggest that pain reliever abuse may precondition a person to engage in heroin use because prescription pain relievers have a similar pharmacological effect as that of heroin, given their similarities in chemical structure. Conversely, prior heroin use appears to be neither a sufficient nor a necessary condition for subsequent non-medical use of pain relievers. Curiously, the report authors do not specify pain relievers in question as being opioids, but those agents are clearly implied in most cases.

As usual, there are limitations to this type of survey, such as not accounting accurately for all heroin users and subgroups. Further, it relies on the honesty of interviewees and their retrospective assessments of drug-use behaviors, which may interject some biases.

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