UNIVERSITY PARK, Pa. — The opioid epidemic in the United States could be responsible for 700,000 overdose deaths between 2016 and 2025, according to a new study published today in JAMA Network Open.

“Preventing people from misusing prescription opioids is important and could help prevent some overdose deaths in the long term, but our study shows that the effect would be limited in reducing the overdose deaths in the immediate future,” said Qiushi Chen, an assistant professor in the Harold and Inge Marcus Department of Industrial and Manufacturing Engineering at Penn State and the lead author on the paper. “The majority of overdose deaths are now from illicit opioids, such as heroin and fentanyl instead of prescription opioids, and this changing nature of the epidemic has reduced the potential impact of programs targeting prescription opioids.”

In an effort to understand the outcomes that programs to limit prescription opioid misuse actually produce, Chen worked with colleagues from Massachusetts General Hospital, Harvard Medical School, and Boston University Medical School.

“The opioid crisis has been a national public health emergency for more than a year, and it’s getting worse,” said Jagpreet Chhatwal, an assistant professor at Harvard Medical School and a decision scientist at Massachusetts General Hospital Institute for Technology Assessment (MGH-ITA). Chhatwal is the senior author on the paper. “We set out to understand how reduction in incidences of prescription opioid misuse, by interventions of restricting opioid prescriptions supply, would influence the outcomes of overdose deaths in the next decade.”

Chen and the team developed a mathematical model to simulate the opioid crisis from 2002 to 2025. Using data available from Centers for Disease Control (CDC) and the National Survey on Drug Use and Health (NSDUH), the researchers calibrated the model to match the trends of overdose deaths from specific types of opioid consumption – recreational prescription misuse to opioid use disorder with prescription and illicit opioids – observed from 2002 through 2015. They then used the model to project probable outcomes of the epidemic, based on the continuing trends, through 2025.

The researchers found that, if that status quo continues, the annual number of opioid overdose deaths will increase from 33,100 in 2015 to 81,700 in 2025 – a 147 percent increase. Eighty percent of those overdose deaths will result from the use of illicit opioids, such as heroin or fentanyl. In every scenario tested, the researchers found that interventions aimed at reducing prescription opioid misuse decreased overdose deaths by three to five percent.

Under an extreme modeling scenario, a hypothetical situation where literally no new incidences of prescription opioid misuse occurred after 2015, the researchers found that number of deaths in 2025 would still remain higher than in 2015.

“More and more people are using illicit opioids. In the past, people might start using pain pills non-medically, which could then lead to illicit opioid usage, but data suggests that even more people are now starting with recreational use of illicit opioids,” Chen said. “Prescription opioids are now not necessarily the gateway that people must use to get to illicit opioids.”

According to the NSDUH, 30 percent of people who developed opioid use disorder did not start with prescription pills, but rather began immediately with heroin or fentanyl. Chen and his team project that the trend will continue, and, by 2025, nearly half of people with opioid use disorder will have initiated their opioid use with illicit drugs.

“This study demonstrates that initiatives focused on the prescription opioid supply are insufficient to bend the curve of opioid overdose deaths in the short and medium term,” said co-author Marc LaRochelle, an assistant professor in the Grayken Center for Addiction at the Boston Medical Center. “We need policy, public health and health care delivery efforts to amplify harm reduction efforts and access to evidence-based treatment.”

Other contributors on this paper include Davis Weaver, a medical student at Case Western University who was a research associate at the MGH-ITA; Anna Lietz, a research associate at the MGH-ITA; Peter Mueller, a postdoctoral fellow at MGH-ITA and Harvard Medical School; Sarah Wakeman, the medical director of the Substance Use Disorders Initiative at MGH and an assistant professor of medicine at Harvard University; Kenneth Freedberg, a professor of medicine at Harvard Medical School and MGH and the director of the Program in Epidemiology and Outcomes Research at the Harvard University Center for Aids Research; Tiana Raphel, a medical student at University of Texas Southwestern Medical School who was a research associate at the MGH-ITA; Amy Knudsen, an assistant professor of radiology at Harvard Medical School and a senior scientist at the MGH-ITA; and Pari Pandharipande, an associate professor of radiology at Harvard Medical School and the director of the MGH-ITA.