Epidemiology of Substance Use and Other Problematic Conditions

Incidence: Rate of new cases of a condition (or an event) during a given period of time

A good example of incidence data are the annual reports of "emergency room episodes" from the Drug Abuse Warning Network or DAWN program, which is sponsored by the National Institute on Drug Abuse. Hospitals that participate in the DAWN program submit an "episode report" for each incident in which a drug abuse patient visits their emergency room, including demographic information about the patient and information about the circumstances of the drug abuse episode. These episodes or incidents might involve an overdose, "the chronic effects of habitual drug use or unexpected reactions, i.e., the drug's effect was different than anticipated (e.g., causing hallucinations). Up to four different substances, in addition to alcohol-in-combination, can be specified for each ER episode" (NIDA, 1988, p. 3). To view a recent DAWN report on the incidence of drug-related ER episodes, click here.

Prevalence: Rate of existing cases, both new and ongoing, at a given point in time (or during a period of time)

Epidemiological data in the area of drug and alcohol problems are more likely to focus on the prevalence of substance use. The Monitoring the Future Project at the University of Michigan is a particularly useful source of data on the prevalence of illegal substance use by adolescents. This project has been collecting data on high school seniors since 1975, and it continues to conduct probability surveys of seniors and younger adolescents annually. The following graphs report the 30-day prevalence of substance use for 2005 and the 30-day prevalence of marijuana and cocaine use since 1975.

30-Day Prevalence
Trends in Marijuana and Cocaine Use

Heroin and Other Narcotic Use

In contrast to relatively stable patterns of use for marijuana, cocaine, heroin (shown below) and many other illegal drugs over the past decade, the thirty-day prevalence of "other narcotic use" by high school seniors has steadily increased since the early 1990s. "Other Narcotics" include opiate-type (or "opioid") prescription drugs such as codeine and Demerol when used outside of medical supervision. In 2002 several new drugs, including OxyContin (Oxycodone) and Vicodin (Hydrocodone), were added to the list of other narcotics in the MTF survey, which accounts in part for a sharp jump in thirty-day prevalence between 2001 and 2002. Overall, monthly prevalence estimates for the use of other narcotics have quadrupled since 1991, and non-medical use of these addictive drugs now ranks fifth in prevalence among high-school seniors behind the use of alcohol, tobacco, marijuana, and amphetamines.

Next Page