Epidemiology of Drug Use and Drug Problems

Part 1. Incidence Rates

Epidemiology, the study of the population rate and distribution of problematic events or conditions, originally developed as a branch of public health and focused primarily on rates of infectious disease. However, contemporary social scientists use epidemiological methods to examine an extensive range of norm-violating phenomena in various populations, including rates of violence, psychiatric disorder, and drug use. In describing rates of disease or other problematic conditions in a given population, epidemiologists distinguish between two types of rate: incidence and prevalence. In general, incidence refers to the rate of new cases of a condition (or an event) during a given period of time.

DAWN emergency department episodes

A good example of incidence data are the annual reports of "emergency department episodes" from the Drug Abuse Warning Network or DAWN program, which is sponsored by the Substance Abuse and Mental Health Services Administration (SAMSHA). Hospitals that participate in the DAWN program submit an "episode report" for each incident in which a patient visits their emergency department (ED) for drug-related problems. These reports include demographic information about the patient and information about the circumstances of the drug abuse episode. Drug-related episodes or "mentions" might involve an accidental or intentional 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 ED episode (NIDA, 1988, p. 3). The DAWN program publishes estimates of the annual incidence of drug-related episodes for the United States as a whole as well as for specific regions of the country. As shown at the left for 2002, cocaine was the most frequently mentioned illegal drug in DAWN emergency department episodes, with a rate of 78 incidents per 100,000 population. To view additional DAWN data on how the incidence of drug-related ED episodes varies across regions of the U.S., click here.

The DAWN data collection system was extensively redesigned in 2003. Because of numerous changes in the type of information collected, the definition of an emergency department visit or "case," the sample of hospitals included in the system, and other aspects of the survey methodology, incidence data from the "new DAWN" cannot be readily compared with DAWN data prior to 2003. This means that DAWN data no longer allow analyses of long-term trends in drug-related emergency room visits. However, a recent report using the new DAWN data found significant increases from 2004 to 2005 in the incidence of emergency department cases related to nonmedical use of pharmaceutical drugs. This included a 24 percent one year increase in cases involving opiod drugs such as OxyContin and Vicodin as well as a 33 percent increase in cases involving "unspecified opiates." These results and an extensive discussion of the incidence data being collected in the redesigned DAWN program are available at http://dawninfo.samhsa.gov/,


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