The National Longitudinal Alcohol Epidemiologic Survey (NLAES) was a National probability survey
sponsored by the National Institute on Alcohol Abuse and Alcoholism (NIAAA). In 1992, the U.S.
Bureau of the Census administered for NIAAA face to face interviews with 42,862 respondents age 18
and older, mean age 44, residing in the non-institutionalized population of the contiguous states including
the District of Columbia.
The multi-stage sampling approach used for NLAES was described by Massey et. al., 198916. Primary
sampling units (PSUs) were stratified according to socioeconomic criteria and were selected with a
probability proportional to their population size. Within PSUs, geographically defined secondary sampling
units, referred to as segments, were selected systematically for the sample. The African American
population was oversampled at this stage of the sample selection to secure adequate numbers for analytic
purposes. Segments were then divided into clusters of 4-8 housing units, and all occupied housing units
were included in the survey. Within each household, one randomly selected person age 18 and older was
selected to participate. Young adults age 18-29 were oversampled at a ratio of 2.25:1.00 at this stage of
sample selection to include a greater representation of this heavier drinking population subgroup.
Weighting using the Survey Data Analysis Statistical Package (SUDAAN)17 adjusted for the deliberate
oversampling of African Americans and persons age 18-29 and accounted for the complex sampling
design of NLAES. The household response rate for this representative sample of the U.S. population was
91.9 percent and the sample person response rate was 97.4 percent. The overall response rate was 90
Alcohol use and alcohol dependence assessment:
Measures of alcohol use and dependence were derived from the Alcohol Use Disorder and Associated
Disabilities Interview Schedule (AUDADIS)18; a fully structured diagnostic psychiatric interview designed
to be administered by trained interviewers who were not clinicians.
The age of drinking onset was ascertained by asking respondents how old they were when they first
started drinking, not counting small tastes or sips of alcohol. Drinking onset data was collected from
respondents who were classified as current drinkers (persons who had consumed at least 12 drinks in the
past 12 months) and former drinkers (persons who had consumed at least 12 drinks in any one year of
their lives but not during the year prior to the interview). Only current and former drinkers were included in
the analysis. In an independent test retest study before the full NLAES was conducted, the test retest
reliability of the drinking onset variable was good with a Kappa of 0.7219.
The definition of lifetime alcohol dependence was based on the diagnostic criteria of the Diagnostic and
Statistical Manual, Fourth Edition (DSM-IV). The AUDADIS interview included an extensive list of
symptom questions that operationalize the DSM-IV criteria for alcohol dependence. Diagnosis of alcohol
dependence required that in any one year a respondent meet at least three of the following seven criteria
for dependence: 1) tolerance, 2) withdrawal or avoidance of withdrawal, 3) persistent desire or
unsuccessful attempts to cut down or stop drinking, 4) spending much time drinking, obtaining alcohol, or
recovering from its effects, 5) giving up or reducing occupational, social, or recreational activities in favor
of drinking, 6) impaired control over drinking and 7) continuing to drink despite a physical or
psychological problem caused or exacerbated by drinking. In the analysis, respondents were classified as
either showing a alcohol dependence diagnosis in the past year, or at any time prior to the past year or
never. The independent test retest study determined good reliabilities with Kappas of 0.76, and .0.73 for
past year and prior to past year dependence diagnoses respectively19.
Family history of alcoholism was ascertained through a series of questions that asked about different types
of first degree biologic relatives (i.e., parents, children and siblings). The respondent was asked how many
of each type of relative lived to be at least 10 years old and how many were ever alcoholics or problem
drinkers. An alcoholic or problem drinker was defined for the respondents in a manner consistent with
DSM-IV criteria for alcohol use disorder
"By an alcoholic or problem drinker, I mean a person who has a physical or emotional problem because
of drinking, problems with a spouse, family or friends because of drinking; problems at work because of
drinking, problems with police because of drinking- like drunk driving-or a person who seems to spend a
lot of time drinking or being hung over."
In a test retest study conducted in conjunction with the NLAES, the family history items showed good to
excellent reliability with Kappas at 0.72 for fathers, 1.00 for mothers, 0.90 for brothers, 0.73 for sisters
and 0.65 each for sons and daughters19. In this study a respondent was classified as Family History
Positive (FHP) if any of their first-degree relatives were reported as having been an alcoholic or a problem
Current heavy drinking was determined by asking respondents, "During the past 12 months, about how
often did you have five or more drinks of any type of alcohol in a single day?" Respondents were also
asked, "About how often would you say you usually drank enough to feel drunk during the last 12
months? By drunk, I mean times when your speech was slurred, you felt unsteady on your feet or you had
We also constructed a measure of the frequency with which respondents drank five or more drinks during
their period of heaviest drinking in their life. Respondents were asked whether there were periods in their
life when they drank more than in the past year. Respondents who answered yes were then asked their
frequency of drinking and the amounts they usually consumed on days they drank during this period. They
were also asked what was the greatest amount they drank on any day during that period and how
frequently they drank that amount. We used data from these questions as well as questions about
frequency of drinking five or more drinks in the past year to determine their frequency of drinking five or
more drinks during their lifetime period of heaviest drinking.
Taking risks that might lead to injury was assessed by a question, "In your life, did you ever get into a
situation while drinking or after drinking that increased your chances of getting hurt - like swimming, using
machinery, or walking in a dangerous area or around heavy traffic? Did that happen in the past 12
months?" Finally, life time and past year alcohol related injury involvement were explored by asking
respondents "In your entire life, did you ever accidentally injure yourself under the influence of alcohol, for
example have a bad fall, or cut yourself badly, get hurt in a traffic accident, or anything like that? Did this
happen in the past 12 months?"
All statistical analyses were conducted using the SUDAAN statistical package to account for the survey
design 17. Age of drinking onset was categorized as under 14, each year separately from 14 through 20,
and 21 or older and all analyses focused only on respondents who responded to this question. The
significance of relations between age of drinking onset and respondent background characteristics was
tested using chi square analysis.
We examined the relation between age of drinking onset and frequency of heavy drinking, adjusting for
background characteristics including history of alcohol dependence through a series of multiple logistic
regression analyses. We examined the following outcomes as dichotomous variables, whether or not
- drank at least 5 + drinks at least once per week in the past year;
- drank to intoxication at least weekly in the past year;
- drank 5+ drinks at least daily during the period when respondents drank most heavily.
Odds ratios and 95% confidence intervals were calculated describing the increased risk of these outcomes
for those with drinking onset before age 14 and at each age from 14 through 20 relative to those who
started drinking after age 21.
To assess whether age of drinking onset was related to injury outcomes, we also conducted multiple
logistic regression analyses examining as dichotomous outcome variables, whether or not respondents ever
or in the past year:
- got into a situation while or after drinking that increased their risk of injury
- accidentally injured themselves under the influence of alcohol.
The regressions were conducted twice. First, we entered the personal social and demographic
characteristics associated with age of drinking onset other than alcohol dependence and measures of
heavy drinking frequency; then we added measures of alcohol dependence and heavy drinking. This was
done to assess whether any relations between age of drinking onset and injury involvement were primarily
a function of those who started drinking earlier in life being more likely to experience more frequent heavy
We entered the frequency of heavy drinking during the respondent's heaviest drinking period into the
regressions examining life time exposure to injury risks and injury involvement, and the past year frequency
of heavy drinking measures into the regressions examining past year exposure to injury risk and injury
For consistency across models, the entire set of background variables was included in the analysis of each
drinking and injury outcome.