To the Editor:

From 2010 through 2013, there was a notable downturn in abuse of prescription opioids and a coincident increase in abuse of heroin in the United States.1 Given that there is some evidence of a relationship between the two trends (e.g., some persons who abuse prescription opioids switch to heroin for a number of reasons and drug interchangeability has been observed),2-4 we sought to examine this relationship more closely, including the validity of reports suggesting regional differences in the balance between prescription opioid and heroin abuse.5

Data on opioid abuse in the previous month were collected quarterly from January 1, 2008, through September 31, 2014, with the use of self-administered surveys that were completed anonymously by independent cohorts of 15,227 patients with opioid dependence, as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, who were entering nonmethadone-maintenance treatment programs throughout the United States. Of these patients, 267 agreed to online interviews to gather qualitative information in order to amplify and interpret findings from the structured national survey.

Figure 1. Figure 1. National Rates of Abuse of Opioids in the Previous Month among 15,227 Respondents. P values calculated with the use of the Cochran–Armitage trend test showed significance between all groups (P<0.001 for all comparisons).

Figure 1 shows the unadjusted rates of abuse of prescription opioids only, abuse of prescription opioids and heroin, or abuse of heroin only among respondents who reported such abuse in the previous month from 2008 through 2014. Rates of exclusive prescription opioid abuse remained stable from 2008 through 2010, at 70%, but then decreased steadily, with an average annual reduction of 6.1%, to less than 50% in 2014. Conversely, concurrent abuse of both heroin and prescription opioids in the previous month increased, with an average annual increase of 10.3%, from 23.6% in 2008 to 41.8% in 2014. Although the exclusive use of heroin was low in this population, it more than doubled from 2008 through 2014 (from 4.3% to 9.0%).

The national data obscure important regional differences (Fig. S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org). The Northeast showed the most striking shifts in patterns of abuse. The West followed closely behind, with concurrent heroin and prescription opioid abuse surpassing exclusive prescription opioid abuse in 2014. The Midwest and South followed similar trends, with the latter showing exclusive prescription opioid abuse to be more prevalent than in any other region.

These findings suggest that as prescription opioid use has waned, concurrent heroin abuse has increased, with important, distinct regional variations. The factors contributing to these evolving changes are not well established. However, in our exploratory qualitative online survey of a subgroup of 267 patients, among the 129 respondents who reported abusing prescription opioids prior to heroin use, 73.0% (92 of 126 respondents) primarily cited practical factors, such as accessibility and cost, when explaining their transition to heroin. Three of the 129 respondents did not provide an explanation for their transition to heroin.

Theodore J. Cicero, Ph.D.

Matthew S. Ellis, M.P.E.

Jessie Harney, M.S.

Washington University, St. Louis, MO

[email protected] edu

Supported by private funds from Washington University School of Medicine in St. Louis and the Researched Abuse, Diversion, and Addiction-Related Surveillance System. Disclosure forms provided by the authors are available with the full text of this letter at NEJM.org.