Alcohol Use

What Is It?

The County Health Rankings attempts to capture the prevalence of excessive alcohol use in the population by looking at people’s reports of alcohol intake and motor vehicle crashes that are frequently the result of alcohol impairment. Excessive drinking, defined by the Behavioral Risk Factor Surveillance System (BRFSS) as binge drinking and/or heavy drinking [1], is a frequently used indicator at the population level. Binge drinking is defined as drinking five or more drinks on a single occasion for men and four or more drinks on a single occasion for women [1]. Heavy drinking is defined as drinking more than two drinks per day on average for men and more than one drink per day on average for women [1]. Motor vehicle crashes are another indicator often used as a proxy for excessive alcohol use, as research has identified drunk driving as a behavior that increases an individual’s risk for being injured or killed in a motor vehicle or for injuring or killing others.[2] The County Health Rankings uses excessive drinking prevalence and motor vehicle crash-related deaths to represent excessive alcohol use.

Why Do We Measure It?

Excessive drinking is a risk factor for a number of adverse health outcomes. These include alcohol poisoning, hypertension, acute myocardial infarction, sexually transmitted infections, unintended pregnancy, fetal alcohol syndrome, sudden infant death syndrome, suicide, interpersonal violence, and motor vehicle crashes.[3] From 2001–2005, there were approximately 80,000 deaths annually attributable to excessive drinking; it is the third leading lifestyle-related cause of death for people in the United States each year. [1] Binge drinking has increased significantly since 1995; currently approximately 30% of drinkers report binge drinking.[4,5] From 2001-2005, binge drinking was involved in approximately 43,700 (55%) of the 80,000 alcohol-attributable deaths in the U.S.[3]

There is a strong association between excessive drinking and alcohol-impaired driving. One study looked at drinking results by drinking category using BRFSS data and found that the binge/non-heavy drinkers contributed to the largest percentage of alcohol-impaired drivers (49%), while binge/heavy drinkers accounted for the most episodes of alcohol-impaired driving.[6] Furthermore, alcohol-related motor vehicle crashes also make up a significant portion of alcohol-related deaths.[4,6]  Approximately 17,000 Americans are killed annually in alcohol-related motor vehicle crashes.[3] The risk of a fatal motor vehicle crash significantly increases with a high blood alcohol concentration of the driver: A driver with a blood alcohol concentration of 100mg/dL or higher is seven times more likely to be involved in a fatal motor vehicle crash, and a driver with a blood alcohol concentration of 150 mg/dL or higher is 25 times more likely to be in a fatal crash compared with a driver who has had no alcoholic beverages.[7]

Measurement Strategies

The only widespread tool for measuring alcohol consumption is through self-reported surveying techniques. The Centers for Disease Control (CDC) sponsors many types of surveys that collect information on alcohol consumption:[8]

The Behavioral Risk Factor Surveillance System (BRFSS) is the world’s largest telephone survey and has the largest coverage, which is important for analyzing data at the county level. It collects data on the number of drinking days, the average number of drinks per occasion, the maximum number of drinks consumed, and the frequency of binge drinking.
The Youth Risk Behavior Survey (YRBS) collects data on high school youth at the national, state, and local levels. However, the coverage is not adequate to use at the county level to analyze trends for youth alcohol consumption.

The National Health Interview Survey (NHIS) collects data on both adults and children in the U.S. through in-person interviews in the home of the respondent. The survey includes questions on alcohol use and binge drinking. However, the small sample size prevents it from being used in the Rankings.

The Pregnancy Risk Assessment Monitoring System (PRAMS) survey provides state level data on maternal attitudes and experiences from expectant mothers (two-six months after giving birth). This survey provides useful information on the number of expectant mothers who engage in alcohol use before and during pregnancy.

Biomarker data, such as breath, blood, and urine tests for alcohol, are non-survey methods that can be useful in validating self-reported data.[9] However, this form of measurement is not currently practical for a population estimate. The sample size that undergoes this type of testing is small, making analysis difficult at the county level. Also, alcohol is metabolized quickly, which allows only a small window of opportunity to get an accurate assessment of a person’s condition.[9]

What Is the County Health Rankings Measurement Strategy?

The County Health Rankings combines two measures to assess alcohol use in a county: percent of excessive drinking in the adult population and the crude motor-vehicle death rate per 100,000 population. The excessive drinking statistics come from county-level Behavioral Risk Factor Surveillance System (BRFSS) data provided to us by the Centers for Disease Control and Prevention (CDC). The BRFSS is a national, random-digit dial telephone survey. BRFSS data is representative of the adult (over age 18), non-institutionalized population living in households with a land-line telephone.[10] The measure aims to quantify the percentage of the population that drinks more than four or five alcoholic beverages in one day at least once a month (known as binge drinking), and/or the percentage of the population that drinks more than one or two drinks per day on average (known as heavy drinking). There have been changes made to these measures in recent years.  From 2000-2005, the survey defined binge drinking as five or more drinks on an occasion and heavy drinking as consuming two or more drinks per day on average, with out regard to gender. Starting in 2006, the definition of binge drinking changed to 5 or more drinks on an occasion for men and 4 or more drinks on an occasion for women, and the definition of heavy drinking changed to more than two drinks per day for men and more than one drink per day for women. [10] [11]

Motor vehicle crash deaths are calculated for the County Health Rankings by the National Vital Statistics System (NVSS) at CDC. Motor vehicle crash deaths are reported as the crude mortality rate per 100,000 people due to on- or off-road accidents involving a motor vehicle. Motor vehicle deaths includes traffic and non-traffic accidents involving motorcycles and 3-wheel motor vehicles; cars; vans; trucks; buses; street cars; ATVs; industrial, agricultural, and construction vehicles; and bikes and pedestrians when colliding with any of the vehicles mentioned.  Deaths due to boating accidents and airline crashes, however, are not included in this measure.

Measure Strengths & Limitations

Excessive Drinking

A study that evaluated the reliability and validity of the self-reported BRFSS measures found that the reliability (repeatability) of the BRFSS alcohol consumption data is high while the validity (accurate representation) of the alcohol consumption data is moderate (but sufficient given the difficulty in assessing the validity of people’s reports of their alcohol use).[9]  
 Using self-reported survey data to assess excessive drinking presents certain limitations. First, excessive drinking is often underreported in surveys because of recall bias, social desirability response bias, and non-response bias.[3] Second, as noted above,BRFSS changed the definition of excessive drinking for women in 2006; this means that there will be a higher prevalence in recent years compared to prior years for women.[3] Third, the measure does not measure youth drinking prevalence. Some U.S. states and counties administer a Youth Behavioral Risk Surveillance Survey, but there is not adequate coverage or consistent enough methodology to aggregate the results to represent all counties across the country.[12] Youth binge drinking prevalence is important because binge drinking accounts for 90% of alcohol consumption for youths ages 12-17. Having a measure that includes youth binge drinking would be beneficial for understanding youth drinking patterns in different counties.[13]

Motor Vehicle Crash Deaths

The motor vehicle crash deaths are calculated using a complete census of deaths due to motor vehicle accidents. Death rates potentially give a more accurate account because they include all (or almost all) cases, whereas BRFSS estimates use a representative sample to calculate an estimate for the population. However, motor vehicle crash deaths present limitations as a proxy for alcohol use on the population level. First, not all motor vehicle crash deaths are attributable to alcohol use. As mentioned above, researchers estimate approximately half of all fatal crashes include alcohol as a contributing factor.[3] This limitation makes the motor vehicle crash death indicator only a crude estimate of alcohol use in a county. Second, there can be a large error margin in counties with small populations, making the data hard to interpret for these counties.

References

[1] Centers for Disease Control and Prevention Web Site: Alcohol and Public Health. http://www.cdc.gov/alcohol/index.htm. Updated January 13, 2011. Accessed February 8, 2011.
[2] Schlundt D, Warren R, Miller S. Reducing unintentional injuries on the nation's highways: A literature review. J Health Care Poor Underserved. 2004;15:76-98.
[3] Centers for Disease Control and Prevention. Sociodemographic differences in binge drinking among adults-14 states, 2004. MMWR Morb Mortal Wkly Rep. 2009;58:301-304.
[4] Naimi TS, Brewer RD, Mokdad A, Denny C, Serdula MK, Marks JS. Binge drinking among US adults. JAMA. 2003;289:70-75.
[5] Mokdad AH, Brewer RD, Naimi T, Warner L. Binge drinking is a problem that cannot be ignored. Prev Med. 2007;44:303-304.
[6] Flowers NT, Naimi TS, Brewer RD, Elder RW, Shults RA, Jiles R. Patterns of alcohol consumption and alcohol-impaired driving in the United States. Alcohol Clin Exp Res. 2008;32:639-644.
[7] Brewer RD, Morris PD, Cole TB, Watkins S, Patetta MJ, Popkin C. The risk of dying in alcohol-related automobile crashes among habitual drunk drivers. N Engl J Med. 1994;331:513-517.
[8] CDC. National surveys that collect information about alcohol consumption. Centers for Disease Control and Prevention Web Site. www.cdc.gov/alcohol/surveillance.htm.  Updated August 6, 2008. Accessed January 26, 2010.
[9] Nelson DE, Holtzman D, Bolen J, Stanwyck CA, Mack KA. Reliability and validity of measures from the Behavioral Risk Factor Surveillance System (BRFSS). Soz Praventivmed. 2001;46:S3-S42.
[10] Health risks in the United States: Behavioral Risk Factor Surveillance System. Centers for Disease Control and Prevention Web Site. www.cdc.gov/nccdphp/publications/aag/brfss.htm. Updated December 17, 2009. Accessed January 26, 2010.
[11] Centers for Disease Control and Prevention. Alcohol Use Among Pregnant and Nonpregnant Women of Childbearing Age --- United States, 1991--2005. MMWR Morb Mortal Wkly Rep. 2009;58:529-532.
[12] CDC. Healthy youth! Frequently asked questions. Centers for Disease Control and Prevention Web Site. www.cdc.gov.HealthyYouth/yrbs/faq.htm. Updated April 2, 2009. Accessed December 15, 2009.
[13] Miller JW, Naimi TS, Brewer RD, Jones SE. Binge drinking and associated health risk behaviors among high school students. Pediatrics. 2007;119:76-85.