Substance use, misuse and dependence: A PLOS Medicine special issue

This week sees publication of the first research papers that will form part of PLOS Medicine's latest Special Issue, which is devoted to understanding the substantial challenges caused by substance use and misuse and seeking to inform responses in the health sector and beyond. Content for the special issue has been selected along with guest editors Margarita Alegria, Steffanie Strathdee and Alexander Tsai.

Substance use is a threat in almost all settings worldwide, and the resulting harms—including transmission of infectious diseases by injection drug use, deaths from overdose, and the complex issues caused by long-term dependence—pose serious problems not only for the people affected and their families but also for health providers, policymakers, those working in criminal justice systems and others.

The current epidemic of opioid use and the ensuing morbidity and mortality, notably the growing burden of overdose deaths, in the United States and other countries has been well recognized in recent years—with the US Centers for Disease Control and Prevention highlighting a daily toll of about 190 drug overdose deaths. In a research paper in the Special Issue, Yu-Jung Jenny Wei of the University of Florida, Gainesville, and co-authors report on documented opioid prescriptions in a cohort of 227,000 adults with a diagnosis of opioid use disorder or overdose in the United States during the period 2005-16. Efforts to curb use of prescription opioids are generally focused on people receiving 90 mg of morphine equivalents per day or more. However, the authors found that about 35% of study participants received no prescription opioids in the year before diagnosis of opioid use or overdose, and two thirds received opioids at a level below the recognized threshold for risk. They comment that programmes seeking to limit use of prescription opioids could be missing a growing proportion of people at risk of harm from opioid misuse.

In a second published study, Joel Hudgins of Boston Children's Hospital, and colleagues, report on prescription opioid use and misuse by adolescents and young adults, based on an analysis of the US National Survey on Drug Use and Health for 2015 and 2016. The authors found that 21% of adolescents (among about 28,000 participants aged 12-17 years) and around 32% of young adults (among about 28,000 participants aged 18-25 years) had used prescription opioids in the previous year, corresponding to an estimated 32.8 million people in the US population in aggregate. Opioid use was more common in women than in men, and opioid misuse was reported by 3.8% of adolescents and 7.8% of young adults. "Prevention and treatment efforts should take into account that greater than half of youths misusing prescription opioids obtain these medications through friends and relatives", the authors say.

In a nationwide study carried out in Sweden, James Kirkbride of University College London, and colleagues from the Karolinska Institute, Sweden, report on substance use disorders in refugee and non-refugee migrant groups. Although refugees are known to be at higher risk of post-traumatic stress disorder than people in the general population, for example, there has been less research on substance use. Data from more than 1.2 million people were included, including 17,700 refugees and 104,200 other migrants, with the Middle East and North Africa being the region of origin for the largest proportions of refugees and migrants. The researchers found that refugees were substantially less likely than Swedish-born individuals to have been diagnosed with a substance use disorder (adjusted hazard ratio 0.52 [95% CI 0.46-0.60]), as were non-refugee migrants (0.46, 0.43-0.49). Risks appeared to converge with those of the Swedish population over time, however, with differences less pronounced in people who had migrated at 0-6 years of age as compared with those migrating after 20 years of age.

Further research and commentary papers for the Special Issue will be published in the coming weeks, and we look forward to ongoing engagement in research focused on understanding and addressing the global crisis in substance use and misuse.