Quality of alcohol use histories collected at intake to substance user treatment.

Many survey questions on alcohol require complex cognitive tasks, such as long-term recall, shifting reference periods, and numeric calculation. Moreover, alcohol-related impairment is known to affect cognitive ability. To assess the quality of data on self-reported alcohol use, internal consistency analyses were conducted as part of a comprehensive multisite prospective study of drug user treatment outcome undertaken in 11 cities throughout the United States (DATOS). Contrary to expectation, analyses found high levels of internal consistency. For questions on age of initiation of different types of alcohol use, over 99% of respondents (N = 2,842) reported consistent answers for each pair of logically related questions. Reports of being drunk and of quantity of alcohol consumed were similarly consistent.