Measuring alcohol intoxication: the development, reliability and validity of an observational instrument.

This study presents an observational instrument designed to assess the presence or absence of alcohol intoxication as well as the level of intoxication. The Alcohol Symptom Checklist (ASC) was validated by comparing the blood alcohol level (BAL) of 672 subjects with the ASC score. The correlation between BAL and ASC for the final version of the scale was .84; alpha reliability = .92; interrater reliability = .93; and mean interitem correlation = .51. These results confirm the scale's reliability, its interrater consistency and its predictive validity. This instrument may be used in place of BAL measures in situations where it would be impractical to obtain samples of blood or alveolar air. The ASC will facilitate naturalistic studies of drinking behavior which previously have been limited by the lack of an unobtrusive method for assessing symptoms of intoxication. In addition, it has potential for use by law enforcement officials in situations where persons suspected of driving while intoxicated refuse to take an evidential breath test. This article examines requirements for training in the use of the ASC, and discusses other potential uses of the instrument.