Our results show a parallel relationship between the availability of prescription opioid analgesics through legitimate pharmacy channels and the diversion and abuse of these drugs and associated adverse outcomes. Availability increased greatly in the 1990s and continued through 2010 but then plateaued from 2011 through 2013. In concert with these findings, four of five RADARS System surveillance programs reported large increases in diversion and abuse from 2002 to 2010. An inflection point was reached in each program, however, and the rates of diversion and abuse of prescription analgesics subsequently decreased.

For the period before 2011, our results are similar to those in other research reports, with increasing rates of opioid analgesic abuse. The Drug Abuse Warning Network reported an increase of 183% in medical emergencies related to opioid pharmaceuticals from 2004 to 2011, the last year for which data are available.18 The National Survey on Drug Use and Health noted increasing dependence on and abuse of prescription pain relievers from 2002 through 2012, the last year for which data are available.19 Similarly, admissions for the treatment of opioid dependence and addiction increased through 2011.20 These increases in drug availability and abuse have been reflected in the numbers of deaths caused by prescription opioids, which increased for 11 consecutive years and reached 16,651 deaths nationally in 2010.2

Few data regarding national trends in prescription-drug abuse and diversion since 2010 have been published. However, emerging data suggest that abuse of prescription opioids may have lessened in some environments. For example, local and state efforts have resulted in a reduction after the enactment of state legislation.6 Florida had a substantial decrease in the diversion of prescription analgesics, especially oxycodone, after several interventions were implemented in 2010 and 2011.7 Reported prescription-drug abuse was also reduced in a study involving college students.21 In contrast, the prevalence of nonmedical use of prescription analgesics remained unchanged in the National Survey on Drug Use and Health through 2012.19

The observed trends in opioid analgesic abuse could be related to several factors. The flattening rate of prescription volume since 2011 may have limited the availability of prescription opioids for abuse. This trend may be evidence of either a decreased supply, because prescribers have reduced the number of prescriptions that they write, or a decreased demand, because the number of patients requesting these drugs has decreased. Although it may be assumed that the prescribers control the supply of a drug, the supply is influenced by persons who feign a painful illness to acquire a prescription. A decrease in requests by these persons will result in a decrease in the number of prescriptions filled. For example, studies show that the introduction of a less desirable formulation of oxycodone can rapidly decrease demand for that formulation.22

Another explanation involves the hundreds of programs implemented by local, state, and federal governments to improve opioid prescribing, reduce doctor-shopping, limit questionable practices by pain clinics, and otherwise improve the use of opioid analgesics in the United States.3 In addition, other organizations have implemented myriad programs such as guidelines for responsible opioid prescribing and educational initiatives designed to decrease experimentation. Prescription-monitoring programs now operate in most states, and early studies indicate their effectiveness.23,24 New opioid analgesic formulations that resist tampering have been introduced. Finally, law enforcement has intervened successfully in some cases, such as closing so-called pill mills in Florida.7 It seems plausible that these efforts have started to take effect.

The role of switching from the abuse of a prescription opioid to the use of high-purity, low-cost heroin must also be considered.25 Our results support this explanation, as do results from the National Survey on Drug Use and Health, in which reported use of heroin in the previous month increased from 2006 to 2012 (Figure 2E).19 The introduction of abuse-deterrent OxyContin coincided with a flattening of the trajectory of opioid analgesic prescriptions but occurred after the increase in reported heroin use became apparent. Given that 79.5% of new heroin initiates in the National Survey on Drug Use and Health reported that their initial drug was a prescription opioid and that reported heroin use by patients in a substance-abuse program nearly doubled after the introduction of abuse-deterrent OxyContin, it seems likely that the reformulation of extended-release oxycodone in 2010 has contributed to the increase in reported heroin use.26,27

Whatever the precise cause, changes in rates of opioid analgesic abuse are associated with increasing heroin-related mortality. The similarities between data from the National Survey on Drug Use and Health and data from the National Poison Data System with respect to heroin use and adverse consequences are striking (Figure 2A and 2E, and Figure 3). A better understanding of the relation between prescription opioid abuse and heroin use is crucial for developing public health policy as well as guiding prevention and treatment initiatives.

The largest threat to the validity of our results is secular change in the study populations. Another concern is methodologic idiosyncrasy resulting in a systematic bias toward reduced diversion and abuse. We believe these explanations for our findings are unlikely because each RADARS program is operated independently by separate principal investigators and each addresses a different aspect of drug abuse. The data source, methods, and data management are different for each program. We cannot identify any programmatic changes that would have created an artifactual decrease in reported opioid use. Further limitations are described in the Supplementary Appendix.

Our results suggest that the United States is making progress in combating the abuse of prescription opioid analgesics. If our observation of decreased abuse is confirmed, changes in public health policy and strategy will be needed.