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1. Introduction

This report presents findings from the 2002 to 2006 National Surveys on Drug Use and Health (NSDUHs) on the use of alcohol by persons aged 12 to 20, that is, those who are under the minimum legal age for alcohol use. NSDUH is an annual survey of the civilian, noninstitutionalized population of the United States aged 12 or older and is conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA). This report examines trends in alcohol use from 2002 to 2006 among underage persons and variations in underage drinking and alcohol use disorders across demographic groups and geographic areas. The discussion is based on measures of alcohol use in the past month, past year, and lifetime included in NSDUH, as well as questions that allow for the classification of past year dependence on or abuse of alcohol. Findings also are presented from items added to the 2006 NSDUH regarding the social context and location of underage drinking, the sources for alcohol among underage drinkers, and the co-occurrence of underage alcohol use and illicit drug use.

1.1. Background

Alcohol is the drug of choice among young people in the United States, and alcohol use constitutes one of the principal public health issues for this population (National Institute on Alcohol Abuse and Alcoholism [NIAAA], 2006). Each year, approximately 5,000 young people under the age of 21 die as a result of underage drinking, including about 1,900 deaths from motor vehicle crashes (Hingson & Kenkel, 2004). Drinking drivers under age 21 are involved in fatal crashes at twice the rate of adult drivers (National Highway Traffic Safety Administration [NHTSA], 2002). Early initiation of alcohol use is associated with higher likelihood of involvement in violent behaviors, suicide attempts, unprotected sexual intercourse, and multiple sex partners (Stueve & O'Donnell, 2005; Swahn, Bossarte, & Sullivent, 2008).

In addition, early initiation of alcohol use has been linked to higher rates of alcohol dependence or abuse in later life (Grant & Dawson, 1997). In the 2006 NSDUH, for example, the rate of alcohol abuse or dependence among adults aged 21 or older was 2.4 percent for those who first used alcohol at age 21 or older compared with 9.6 percent among those who initiated alcohol use prior to age 21 and 16.3 percent among those who first used alcohol before age 15 (Office of Applied Studies [OAS], 2007a). An estimated 38.7 percent of adults age 21 or older with past year alcohol dependence or abuse initiated alcohol use before age 15 (OAS, 2007b).

Information from several national sources indicates that underage alcohol use is widespread. According to the 2006 NSDUH, about 10.8 million persons aged 12 to 20 (28.3 percent of this age group) reported drinking in the past month (OAS, 2007a). Approximately 7.2 million (19.0 percent) were binge drinkers (consumed five or more drinks at the same time or within a couple of hours of each other on at least 1 day in the past 30 days), and 2.4 million (6.2 percent) were heavy drinkers (five or more drinks on the same occasion on each of 5 or more days in the past 30 days). The percentage of underage persons reporting past month alcohol use was similar from 2002 to 2006, according to the 2006 NSDUH. The 2006 Monitoring the Future (MTF), a survey of 8th, 10th, and 12th graders that also includes a follow-up of persons who had participated in the survey as high school seniors, indicated that 17.2 percent of 8th graders, 33.8 percent of 10th graders, 45.3 percent of 12th graders, and 57.6 percent of those aged 19 or 20 had consumed alcohol in the past month (Johnston, O'Malley, Bachman, & Schulenberg, 2007a, 2007b). Furthermore, 6.2 percent of 8th graders indicated that they had been drunk in the past month, as did 18.8 percent of 10th graders, 30.0 percent of 12 graders, and 42.5 percent of those aged 19 or 20. Data from the Treatment Episode Data Set (TEDS) indicate that in 2006 there were over 61,000 admissions to substance abuse treatment among persons aged 12 to 20 in which alcohol was the primary substance of abuse, a number that represented 24.1 percent of all substance abuse treatment admissions for this age group (Substance Abuse and Mental Health Data Archive [SAMHDA], 2008).

Reduction of underage alcohol use has been highlighted as a top health priority of the Federal Government. In 2007, the Surgeon General issued a Call to Action to Prevent and Reduce Underage Drinking to highlight the nature and extent of underage drinking and to focus the attention of the public on this enduring problem (U.S. Department of Health and Human Services [DHHS], 2007). As part of SAMHSA's leadership role to coordinate the Federal effort to address this problem, the agency has issued A Comprehensive Plan for Preventing and Reducing Underage Drinking that outlines a detailed, goal-driven plan to reduce underage drinking (DHHS, 2006). Currently, SAMHSA sponsors two workgroups that address the underage drinking problem, one internal to SAMHSA and the other involving other agencies. SAMHSA's internal workgroup coordinates the agency's activities with regard to the prevention and treatment of alcohol-related problems and addresses such topics as the prevention of underage drinking, adolescent treatment, the prevention of excessive drinking by those of legal age, and alcohol treatment in general. The Interagency Coordinating Committee on the Prevention of Underage Drinking, which includes members from NIAAA, NHTSA, and other agencies in addition to SAMHSA, was responsible for developing SAMHSA's Report to Congress on the Prevention and Reduction of Underage Drinking.

This analytic series report, the first full-length NSDUH report to focus solely on underage drinking, complements these recent and ongoing efforts. NSDUH's large sample of the population aged 12 to 20 (more than 158,000 respondents in this age range from 2002 to 2006 combined), its inclusion of items to measure alcohol use and alcohol use disorders, and the added items on the context, location, and co-occurrence of alcohol use and illicit drug use make the survey a unique source of data to address the issue of underage alcohol use. NSDUH provides estimates that are representative at both the national level and within each State. It has sufficient sample size to examine the prevalence of rare drug use patterns, to study trends from 2002 to 2006, and to investigate differences in prevalence and other indicators across demographic groups, socioeconomic circumstances, and geographic areas.

1.2. General Information about NSDUH

NSDUH is the primary source of statistical information on the use of alcohol and illicit drug use by the U.S. civilian, noninstitutionalized population aged 12 or older. Conducted by the Federal Government since 1971, the survey collects data by administering questionnaires to a representative sample of the population through face-to-face interviews at their places of residence. The survey, which has been repeated annually since 1990, is sponsored by SAMHSA, an operating division of the DHHS, and is planned and managed by OAS within SAMHSA. Data collection is conducted under contract with RTI International, Research Triangle Park, North Carolina.1 This section briefly describes the survey methodology; a more complete description is provided in Appendices A and B.

Prior to 2002, the survey was called the National Household Survey on Drug Abuse (NHSDA). Because of improvements to the survey in 2002, the 2002 data constitute a new baseline for tracking trends in substance use and other measures. Estimates from 2002 to 2006 included in this report should not be compared with estimates from the 2001 or earlier versions of the survey to examine changes in underage alcohol use over time.

Particular strengths of the NSDUH data for reporting on underage alcohol use in the United States include, but are not limited to, the probability sampling design and large sample sizes (see below). Data are weighted to allow inferences to be made for the civilian, noninstitutionalized population aged 12 or older in the United States and for specific demographic subgroups (such as those aged 12 to 20) and geographic subgroups within the United States. Large sample sizes and probability sampling yielding representative estimates in each of the 50 States and the District of Columbia ensure coverage of even relatively rare behaviors and provide a high level of precision in the national estimates, particularly when survey data are pooled across multiple years.

NSDUH collects information from residents of households, noninstitutional group quarters (e.g., shelters, rooming houses, dormitories), and civilians living on military bases. The survey does not include homeless persons who do not use shelters, military personnel on active duty, and residents of institutional group quarters, such as jails and hospitals.

Since 1999, the NSDUH interview has been carried out using computer-assisted interviewing (CAI). Most of the questions are administered with audio computer-assisted self-interviewing (ACASI). ACASI is designed to provide the respondent with a highly private and confidential means of responding to questions to increase the level of honest reporting of illicit drug use and other sensitive behaviors. Less sensitive items are administered by interviewers using computer-assisted personal interviewing (CAPI).

The 2002 to 2006 NSDUHs employed a State-based design with an independent, multistage area probability sample within each State and the District of Columbia. The eight States with the largest population (California, Florida, Illinois, Michigan, New York, Ohio, Pennsylvania, and Texas), which together account for 48 percent of the total U.S. population aged 12 or older) were designated as large sample States. For the remaining 42 States and the District of Columbia, smaller, but adequate, samples were selected. In this report, State variations are studied using direct, weighted, and design-based estimates from the sample. For these estimates, 5 years of data (2002 to 2006) were combined to obtain sample sizes sufficient to produce State estimates and estimates for small demographic groups that met the precision criteria for publication (see Appendix A). The NSDUH design also oversampled persons aged 12 to 17 and those aged 18 to 25, so that each State's sample was approximately equally distributed among three major age groups: 12 to 17 years, 18 to 25 years, and 26 years or older.

Each year's survey was conducted from January through December of that calendar year (e.g., January through December 2006 for the 2006 NSDUH). Sampled dwelling units were screened to identify eligible residents aged 12 or older. Up to two persons per dwelling unit were selected to be interviewed. In each year, respondents were given an incentive payment of $30 for completing the interview.

Weighted response rates for household screening ranged from 90.6 to 91.3 percent for these 5 survey years. Weighted response rates for interviewing ranged from 74.2 to 78.9 percent. Sample sizes were 68,126 in 2002, 67,784 in 2003, 67,760 in 2004, 68,308 in 2005, and 67,802 in 2006, for a total of 339,780 completed interviews for all those aged 12 or older across the 5 years. Sample sizes just for those aged 12 to 20 were 32,787 in 2002, 31,475 in 2003, 31,235 in 2004, 31,282 in 2005, and 31,320 in 2006, for a total of 158,099 completed interviews for those aged 12 to 20 across the 5 years. The weighted response rates for interviewing among those aged 12 to 20 were 89.2 percent in 2002, 88.5 percent in 2003, 88.0 percent in 2004, 86.8 percent in 2005, and 84.9 percent in 2006.

1.3. Measures of Alcohol Use and Disorders

NSDUH includes questions about the recency and frequency of consumption of alcoholic beverages, such as beer, wine, whiskey, brandy, and mixed drinks. An extensive list of examples of the kinds of beverages covered is given to respondents prior to the question administration. A "drink" is defined as a can or bottle of beer, a glass of wine or a wine cooler, a shot of liquor, or a mixed drink with liquor in it. Times when the respondent only had a sip or two from a drink are not considered to be consumption.

For this report, estimates for the prevalence of alcohol use are reported primarily at five levels defined for both males and females and for all ages as follows:

NSDUH includes questions designed to measure dependence on and abuse of alcohol based on the criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) (American Psychiatric Association [APA], 1994). A respondent was defined as having dependence on alcohol if he or she met three or more of the following seven dependence criteria:

  1. Spent a great deal of time over a period of a month getting, using, or getting over the effects of alcohol.

  2. Used alcohol more often than intended or was unable to keep set limits on the alcohol use.

  3. Needed to use alcohol more than before to get desired effects or noticed that the same amount of alcohol had less effect than before.

  4. Inability to cut down or stop using alcohol every time tried or wanted to.

  5. Continued to use alcohol even though it was causing problems with emotions, nerves, mental health, or physical problems.

  6. Alcohol use reduced or eliminated involvement or participation in important activities.

  7. Experienced withdrawal symptoms (e.g., having trouble sleeping, cramps, hands tremble).

A respondent was defined as having abused alcohol if he or she met one or more of the following four abuse criteria and was determined not to be dependent on alcohol in the past year:

  1. Serious problems at home, work, or school caused by alcohol, such as neglecting your children, missing work or school, doing a poor job at work or school, or losing a job or dropping out of school.

  2. Used alcohol regularly and then did something that might have put you in physical danger.

  3. Use of alcohol caused you to do things that repeatedly got you in trouble with the law.

  4. Had problems with family or friends that were probably caused by using alcohol and continued to use alcohol even though you thought alcohol use caused these problems.

Criteria used to determine whether a respondent was asked the dependence and abuse questions included responses from the core alcohol use questions and the frequency of alcohol use questions, as well as the noncore alcohol use questions. Missing or incomplete responses in the core alcohol use and frequency of use questions were imputed. However, the imputation process did not take into account reported data in the noncore questions, including those on dependence and abuse. Respondents with missing information on dependence or abuse (3.5 percent of past year users aged 12 to 20) were included in the analyses, but they were not counted as having dependence or abuse.

1.4. New Alcohol Use Items in the 2006 NSDUH

The 2006 NSDUH included a new module on consumption of alcohol that asked for additional information about respondents' last use of alcohol for those who indicated that they had consumed alcohol at least once in the past month. In this module, past month drinkers were asked to think about the last time they used alcohol and then were asked to provide the following information about their last drinking occasion:

In addition, respondents of all ages who indicated that they had binged on alcohol at least once in their life also were asked about their age when they first binged on alcohol. Respondents who indicated an age of first binge episode that was the same as their current age or 1 year younger than their current age were then asked to give the month and year when they first binged, which enabled a measure of initiation of binge alcohol use in the year prior to the survey.

Moreover, females who were lifetime drinkers were asked whether they had ever had four or more drinks on the same occasion, as well as their age when they first had four or more drinks on the same occasion. These two questions enable a comparison of binge drinking rates based on the definition used previously by NSDUH, which was five or more drinks on the same occasion for both males and females, and an alternative definition used by the NIAAA (2004), which is five or more drinks on the same occasion for males and four or more drinks on the same occasion for females.

Findings based on most of the items in the new consumption of alcohol module are presented in Chapter 4 and the tables in Appendix C. Section B.4 of Appendix B presents additional technical information and findings from items in this module.

1.5. Measures of Demographic and Geographic Characteristics

Data are presented for racial/ethnic groups in several categorizations, based on current standards for collecting and reporting race and ethnicity data (Office of Management and Budget [OMB], 1997) and on the level of detail permitted by the sample. Because respondents were allowed to choose more than one racial group, a "two or more races" category is presented that includes persons who reported more than one category among the seven basic groups listed in the survey question (white, black or African American, American Indian or Alaska Native, Native Hawaiian, Other Pacific Islander, Asian, Other). It should be noted that, except for the "Hispanic or Latino" group, the racial/ethnic groups discussed in this report include only non-Hispanics. The category "Hispanic or Latino" includes Hispanics of any race. Also, more detailed categories describing specific subgroups were obtained from survey respondents if they reported either Asian race or Hispanic ethnicity. Data on Native Hawaiians and Other Pacific Islanders are combined in this report.

Data also are presented for four U.S. geographic regions in this report. These regions and the nine geographic divisions within those regions, as defined by the U.S. Census Bureau, consist of the following groups of States:

Northeast Region - New England Division: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont; Middle Atlantic Division: New Jersey, New York, Pennsylvania.

Midwest Region - East North Central Division: Illinois, Indiana, Michigan, Ohio, Wisconsin; West North Central Division: Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota.

South Region - South Atlantic Division: Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia; East South Central Division: Alabama, Kentucky, Mississippi, Tennessee; West South Central Division: Arkansas, Louisiana, Oklahoma, Texas.

West Region - Mountain Division: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming; Pacific Division: Alaska, California, Hawaii, Oregon, Washington.

Geographic comparisons also are made based on county type, which reflects different levels of urbanicity and metropolitan area inclusion of counties, based on metropolitan area definitions issued by the OMB in June 2003 (OMB, 2003). For this purpose, counties are grouped based on the 2003 rural-urban continuum codes. These codes were originally developed by the U.S. Department of Agriculture (Butler & Beale, 1994). Each county is either inside or outside a metropolitan statistical area (MSA), as defined by the OMB.

Large metropolitan areas have a population of 1 million or more. Small metropolitan areas have a population of fewer than 1 million. Small metropolitan areas are further classified based on whether they have a population of 250,000 or more. Nonmetropolitan areas are areas outside MSAs. Counties in nonmetropolitan areas are further classified based on the number of people in the county who live in an urbanized area, as defined by the U.S. Census Bureau at the subcounty level. "Urbanized" counties have 20,000 or more population in urbanized areas, "less urbanized" counties have at least 2,500 but fewer than 20,000 population in urbanized areas, and "completely rural" counties have fewer than 2,500 population in urbanized areas.

1.6. Organization of This Report

This report contains separate chapters that discuss the following topics related to the use of alcohol by persons aged 12 to 20: trends in underage alcohol use and disorders from 2002 to 2006 (Chapter 2); patterns of underage alcohol use and alcohol use disorders by demographic and geographic groups (Chapter 3); and the social context and location of underage drinking, the sources of alcohol for underage drinkers, and the co-occurrence of underage drinking and illicit drug use (Chapter 4). Most analyses are presented for all underage persons aged 12 to 20 and by gender and age group (12 to 14, 15 to 17, 18 to 20). Technical appendices describe NSDUH (Appendix A) and its statistical methods and measurement (Appendix B). Appendix C contains the tables of estimates referenced in Chapters 2 through 4. Tables showing standard errors for the estimated numbers and percentages in the tables in Appendix C are available on the SAMHSA/OAS website at http://samhsa.gov/data/WebOnly.htm.

Tables, text, and figures present prevalence measures for the population in terms of both the number of alcohol users and the rate of alcohol use for those aged 12 to 20. The tables and figures for Chapter 2 include trend data that are based on comparisons of single-year estimates between 2002 to 2006. In these tables and figures showing trend data, significant differences between estimates from 2006 and previous years of the survey are indicated. The tables and figures for Chapter 3 are based on averages for 2002 to 2006; combining data from these 5 survey years increases the sample sizes to support detailed estimates. The tables and figures for Chapter 4 are based on new items added to NSDUH in 2006.

Statistical tests have been conducted for all statements appearing in the text of the report that compare estimates between years or subgroups of the population. Unless explicitly stated that a difference is not statistically significant, all statements that describe differences are significant at the .05 level. Statistically significant differences are described using terms such as "higher," "lower," "increased," and "decreased." Statements that use terms such as "similar," "no difference," "same," or "remained steady" to describe the relationship between estimates denote that a difference is not statistically significant. In addition, a set of estimates for survey years or population subgroups may be presented without a statement of comparison, in which case a statistically significant difference between these estimates is not implied and testing was not conducted.

All estimates presented in the report have met the criteria for statistical reliability (see Appendix B). Estimates that do not meet these criteria are suppressed and do not appear in tables, figures, or text. Also, subgroups with suppressed estimates are not included in statistical tests of comparisons. For example, a statement that "whites had the highest prevalence" means that the rate among whites was higher than the rate among all nonsuppressed racial/ethnic subgroups, but not necessarily higher than the rate among a subgroup for which the estimate was suppressed.


End Note

1 RTI International is a trade name of Research Triangle Institute.

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