Research evaluates overdose death definitions used in statistics, suggests revision

July 09, 2013
According to national statistics, deaths from drug overdose have increased consistently since the early 1990s. New research, however, suggests that those numbers may not be accurate and deserve closer examination.
Dr. Nab Dasgupta

Dr. Nab Dasgupta

Nabarun Dasgupta, PhD, 2013 epidemiology alumnus of the Gillings School of Global Public Health, worked with colleagues at The University of North Carolina at Chapel Hill and the N.C. Department of Health and Human Services to examine records for all deaths in North Carolina between Jan. 1, 2008, and Dec. 31, 2011. The researchers found that up to 16 percent of deaths considered “overdoses” by national authorities did not involve controlled substances.

Their study, “Defining Controlled Substances Overdose: Should Deaths from Substance Use Disorders and Pharmaceutical Adverse Events be Included?,” finds that commonly used definitions are too broad, leading to the simultaneous reporting of deaths unrelated to the use of controlled substances and the under-reporting of deaths that are related.
Published June 6 in the Journal of Clinical Toxicology, the research proposes a new definition of “overdose death” that includes deaths from substance use disorders, but not deaths due to severe side effects involving prescription medicines that are not controlled substances (pharmaceutical adverse events).
“There is considerable interest in the timely and accurate identification of deaths from controlled substances,” Dasgupta said. “What we’ve found is that deaths from negative reactions to blood pressure medicine, for example, are being coded in the same way as deaths related to controlled substances such as heroin or cocaine, and that the latter are being underreported. The underlying cause of these deaths is vastly different, and the policy and behavioral changes needed to prevent them are distinct.”
Dasgupta said the newly proposed definition would help garner more accurate estimates of the number of overdose deaths that involve illicit drugs and prescription medicines that lend themselves to abuse. “If you are evaluating an intervention that prevents drug abuse, you would not expect medication errors to decrease across the board,” he said.
The research has implications for evaluating effectiveness of national measures to reduce overdose deaths, such as the Food and Drug Administration’s Risk Evaluation and Mitigation Strategies (REMS) for long-acting and extended-release opioid analgesics. Since 1999, state and national statistics used to track drug-related deaths and inform policy decisions have relied on the World Health Organization’s International Classification of Disease 10th Revision (ICD-10). Dasgupta’s research will assist authorities in developing more accurate definitions for overdose in future revisions of the ICD.
Gillings School co-authors are Catherine Sanford, MSPH, adjunct assistant professor of maternal and child health; Michele Jonsson Funk, PhD, research assistant professor, and Carri Casteel, PhD, research associate professor, both in the Department of Epidemiology; Kurt Ribisl, PhD, professor of health behavior; and Steve Marshall, PhD, professor of epidemiology and director of the UNC Injury Prevention Research Center (IPRC).
Scott Proescholdbell, MPH, public health epidemiologist in the Injury and Violence Prevention Branch of the N.C. Department of Health and Human Services’ Division of Public Health, is also a co-author.
Sanford and Casteel also are affiliated with UNC’s IPRC.
The study was funded by the Robert Wood Johnson Foundation’s Public Health Law Research program.
The Robert Wood Johnson Foundation focuses on pressing health and health care issues facing people in the U.S. As the nation’s largest philanthropy devoted exclusively to improving the health and health care of all Americans, the Foundation works with a diverse group of organizations and individuals to identify solutions and achieve comprehensive, meaningful and timely change.
Public Health Law Research is a national Robert Wood Johnson Foundation program dedicated to building the evidence base for laws that improve public health. With direction and technical assistance from Temple University, the program funds research, improves research methods, and makes evidence more accessible to policy makers, the media and the public.


Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or