Medscape, LLC is pleased to provide online continuing medical education (CME) for this journal article, allowing clinicians the opportunity to earn CME credit.

This activity has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Medscape, LLC and Preventing Chronic Disease. Medscape, LLC is accredited by the ACCME to provide continuing medical education for physicians.

Medscape, LLC designates this Journal-based CME activity for a maximum of 1 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

All other clinicians completing this activity will be issued a certificate of participation. To participate in this journal CME activity: (1) review the learning objectives and author disclosures; (2) study the education content; (3) take the post-test with a 75% minimum passing score and complete the evaluation at www.medscape.org/journal/pcd (4) view/print certificate.

Release date: November 20, 2014; Expiration date: November 20, 2015

Excessive alcohol consumption is responsible for an average of 88,000 deaths each year and cost the United States $223.5 billion in 2006 (1,2). Half of these deaths and three-quarters of the economic costs are due to binge drinking (ie, ≥4 drinks for women and ≥5 drinks for men in a single occasion) (1,3). Binge drinking is also associated with a myriad of health and social problems (eg, violence, new HIV infections, unintended pregnancies, and alcohol dependence) (4,5).

It is often assumed that most excessive drinkers are alcohol dependent. However, few studies have examined the prevalence of alcohol dependence among excessive drinkers — specifically among binge drinkers. Access to such information is important to inform the prioritization of strategies to prevent excessive drinking and treat alcohol dependence. Because binge drinkers are at higher risk than non-binge drinkers for alcohol dependence (6), population-based policies offer an important way to prevent alcohol dependence. The clinical diagnosis of alcohol dependence is based on criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM), Fourth Edition, and involves the assessment of warning signs such as tolerance, withdrawal, impaired control, and unsuccessful attempts to cut down (7).

Data from the 2002 New Mexico Behavioral Risk Factor Surveillance System (BRFSS) found that 10.7% of excessive drinkers (ie, binge drinkers, heavy drinkers, or alcohol-impaired drivers) and 8.1% of binge drinkers met diagnostic criteria for alcohol dependence (8). A study of the 2001–2002 National Epidemiologic Survey of Alcohol-Related Conditions (NESARC) found that the prevalence of alcohol dependence among binge drinkers aged 18 or older was 4.4% among those with 1 to 11 binge drinking occasions in the previous year and jumped to 21.9% among those with 12 or more binge drinking occasions in the previous year (9).

There are no current estimates of the prevalence of alcohol dependence among US adults based on patterns of drinking. The objective of this study was to update prior estimates of the prevalence of alcohol dependence among US adult drinkers. If most binge drinkers do not meet the diagnostic criteria for alcohol dependence, evidence-based policy strategies and clinical preventive services may effectively reduce binge drinking in most cases without requiring addiction treatment.

From 2009 to 2011, the prevalence of past-year drinking among adults was 70.5% (95% CI, 70.0%–70.9%), the prevalence of past-month excessive drinking was 29.3% (95% CI, 28.9%–29.7%), the prevalence of past-month binge drinking was 27.4% (95% CI, 27.0%–27.8%), and the prevalence of DSM-IV alcohol dependence among all respondents was 3.5% (95% CI, 3.3%–3.6%) (Table 1). The prevalence of excessive drinking, binge drinking, and alcohol dependence were highest among men, those aged 18 to 24, and those who were unemployed. Binge drinking was more common among Native Hawaiians or other Pacific Islanders (31.8%; 95% CI, 24.1%–40.6%) and non-Hispanic whites (28.6%; 95% CI, 28.1%–29.1%) than among other racial/ethnic groups, but most of these differences were not significant. In contrast, the prevalence of alcohol dependence among current drinkers was significantly higher among American Indians or Alaskan Natives (9.0%; 95% CI, 6.8%–11.8%) relative to other racial/ethnic groups.

When evaluated by education, the prevalence of binge drinking was significantly higher among those with some college education (30.1%; 95% CI, 29.3%–30.8%) than among those with other levels of education. However, the prevalence of alcohol dependence among those with less than a high school education (4.3%; 95% CI, 3.9%–4.8%) was significantly higher than among those with a high school education or college education but not higher than the prevalence among those with some college. The prevalence of binge drinking was also significantly higher among those with an annual family income of $75,000 or more (28.8%; 95% CI, 28.1%–29.6%) than among those with lower family incomes, whereas the prevalence of alcohol dependence was significantly higher among those with an annual family income of less than $25,000 (4.8%; 95% CI, 4.5%–5.2%) than among those in other income groups (Table 1).

When evaluated by drinking pattern, the prevalence of alcohol dependence was 10.2% (95% CI, 9.8%–10.6%) among excessive drinkers, 10.5% (95% CI, 10.1%–11.0%) among binge drinkers, and 1.3% (95% CI, 1.2%–1.5%) among non-binge drinkers (Table 2). The prevalence of alcohol dependence was significantly higher among excessive drinkers and binge drinkers than among non-binge drinkers across all sociodemographic groups. In contrast, the prevalence of alcohol dependence was similar among excessive drinkers and binge drinkers across most groups except those aged 18 to 24, among whom the prevalence of alcohol dependence was significantly higher among binge drinkers (13.2%; 95% CI, 12.7%–13.8%) than among excessive drinkers (11.9%; 95% CI, 11.4%–12.4%).

Among binge drinkers, the prevalence of alcohol dependence was significantly higher among men (11.1%; 95% CI, 10.6%–11.7%) than among women (9.7%; 95% CI, 9.0%–10.3%) (Table 2). It was also highest among binge drinkers aged 18 to 24 (13.2%; 95% CI, 12.7%–13.8%); it then decreased significantly with increasing age. Binge drinkers who were American Indians or Alaskan Natives had a significantly higher prevalence of alcohol dependence than those in other racial/ethnic groups (28.1%; 95% CI, 21.4%–36.0%), as did binge drinkers with less than a high school education (14.2%; 95% CI, 12.9%–15.7%), an annual family income of less than $25,000 (14.9%; 95% CI, 13.9%–15.9%), and those who were unemployed (14.8%; 95% CI, 13.2%–16.5%), compared with those in other groups in the same sociodemographic category (ie, education, income, and employment).

The prevalence of alcohol dependence increased significantly with the frequency of binge drinking in the past month, ranging from 4.3% (95% CI, 3.9%–4.8%) among those who reported binge drinking 1 or 2 times in the past month to 29.8% (95% CI, 28.1%–31.9%) among those who reported binge drinking 10 or more times in the past month (Figure).

This study found that about 9 of 10 adult excessive drinkers did not meet the diagnostic criteria for alcohol dependence. About 90% of the adults who drank excessively reported binge drinking, and the prevalence of alcohol dependence was similar among excessive drinkers and binge drinkers across most sociodemographic groups. The prevalence of alcohol dependence also increased with the frequency of binge drinking. However, even among those who reported binge drinking 10 or more times in the past month, more than two-thirds did not meet diagnostic criteria for alcohol dependence according to their responses to the survey.

The prevalence of alcohol dependence among adult excessive drinkers and binge drinkers in this study was slightly higher than the prevalence reported in other studies using the same diagnostic criteria for the classification of alcohol dependence. A 2001 study of alcohol abuse and dependence among US adults using the National Household Survey on Drug Abuse (NHSDA) — the precursor to the NSDUH — found that the prevalence of alcohol dependence was 7.4% among men and 7.3% among women who reported binge drinking (13). The higher prevalence of alcohol dependence among binge drinkers in this study may be due to the different time period as well as differences in the survey methods, which make these estimates not directly comparable (14). The former NHSDA was redesigned in 1999, and other changes were made to the survey in 2002, which may have increased the sensitivity of the NSDUH for identifying people who are binge drinking and alcohol dependent.

Differences in the prevalence of alcohol dependence between the current study and the 2002 study in New Mexico (10.7% among excessive drinkers and 8.1% among binge drinkers) (8) are probably due to differences in the survey methods used by the NSDUH and the BRFSS as well as differences in the populations studied (15).

Consistent with previous studies, binge drinking was most common among men, those aged 18 to 24, non-Hispanics whites, those with some college education, and those with an annual family income $75,000 or more (16). In contrast, alcohol dependence was most common among American Indians or Alaskan Natives, those having less than a high school education, and those with an annual family income of less than $25,000. These findings may reflect the known impact of alcohol dependence on many areas in the drinker’s life, including their ability to work and their productivity in the workplace. Reduced workplace productivity is the single largest contributor to alcohol-attributable economic costs in the United States (1).

The strong relationship between the prevalence of excessive drinking and binge drinking is also consistent with the findings of previous studies (17), as is the higher prevalence of alcohol dependence among binge drinkers relative to all current drinkers (8), and the positive relationship between the frequency of binge drinking and alcohol dependence (18). These findings emphasize the usefulness of screening for binge-level alcohol consumption to identify excessive drinking among adults, including those who are alcohol-dependent (19). The relatively low prevalence of alcohol dependence among people who drink excessively also suggests that most people who are screened for excessive drinking in clinical settings will probably not need to be referred for specialized treatment.

This study has several limitations. First, data for this study are based on self-reported alcohol consumption, which tends to be underreported (20). However, NSDUH estimates of the prevalence of binge drinking among adults are significantly higher than those from other surveys of adults, such as the BRFSS (16). In addition, although the classification of alcohol dependence in this study is based on self-reported responses to a survey, the questions used to assess substance use disorders in the NSDUH have been found to be sensitive and specific for identifying alcohol dependence among adults when tested in clinical settings (21). Second, although the NSDUH collects information from residents of households and noninstitutional group quarters (eg, shelters, rooming houses, dormitories) and from civilians living on military bases, the survey does not include homeless persons who were not living in shelters, military personnel on active duty, and residents of institutional group quarters (eg, jails, long-term care facilities), and the prevalence of excessive drinking — including alcohol dependence — is known to be higher in some of these populations (22,23). Third, the 2009–2011 NSDUH classified alcohol dependence by using DSM-IV criteria. In contrast, the new Diagnostic and Statistical Manual of Mental Disorders, Version 5 (DSM-5) defines a spectrum of alcohol use disorders, and based on these diagnostic criteria, alcohol dependence would be classified as a severe alcohol use disorder. However, a study of patients with a known substance use disorder found that the prevalence of severe alcohol use disorders was only 0.5% higher than the prevalence of alcohol dependence (24). Another study assessing the drinking behavior of the general population (using data from the 2004–2005 NESARC survey) estimated that the prevalence of severe alcohol use disorders based on DSM-5 diagnostic criteria was only about 1.1% higher than the prevalence of alcohol dependence according to DSM-IV criteria (25). Taken together, these findings suggest that the use of DSM-IV diagnostic criteria for alcohol dependence in this study probably resulted in only a slightly lower estimate of the prevalence of severe alcohol problems than would have been obtained using DSM-5 diagnostic criteria.

The findings of this study have important implications for planning and implementing public health interventions to reduce excessive drinking and binge drinking at the population level. Although alcohol dependence is an important public health problem, these findings suggest that most excessive drinkers are unlikely to need addiction treatment. Studies have also found that binge drinking, in particular, is strongly affected by alcohol policies in states (26). The Community Preventive Services Task Force recommends several policy strategies for reducing excessive alcohol use and related harms that are likely to be effective across many sociodemographic categories, including increasing alcohol taxes, regulating alcohol outlet density, and dram shop (commercial host) liability (27).

The US Preventive Services Task Force also recommends alcohol screening and brief counseling for excessive alcohol use among adults in primary care settings (28). However, recent studies have found that these prevention strategies are underused — probably because of timing constraints, lack of training, discomfort with discussing substance use, or insurance coverage limitations. The uptake of alcohol screening and brief interventions might be improved by offering health care providers more training opportunities and by including coverage for alcohol screening and brief interventions in standard health insurance plans (19,29). A comprehensive approach to reducing excessive alcohol use that emphasizes the implementation of effective policy strategies and clinical preventive services, similar to the Best Practices for Comprehensive Tobacco Control Programs — 2007 (30), might therefore be expected to have a greater impact on reducing excessive alcohol use and related harms than a more focused strategy that primarily relies on the implementation of addiction treatment services alone.