Concurrent validity of the CAGE questionnaire. The Nord-Trøndelag Health Study

The aim of this study was to examine the psychometric properties of the CAGE questionnaire, and the questionnaire's concurrent validity with current and previous alcohol consumption. This study employed data from the Nord-Trøndelag Health Survey wave 1 (HUNT-1 in 1984-86: N=24,900) and wave 2 (HUNT-2 in 1995-97: N=36,350). The concurrent validity of the CAGE questionnaire was examined both as a dichotomous variable with the recommended cut-off (≥2 affirmative answers) for alcohol problems, and as a categorical scale. The categorical scale was constructed by counting responses from 0 to 4, and a separate category for current abstainers in HUNT-2. Current self-reported consumption above the gender specific 80th percentile was defined as "current excessive consumption". "Previous excessive consumers" were defined by meeting at least one of the two following criteria at the time of HUNT-1: reporting drinking too much alcohol in any period of their life, or reporting a high level of alcohol consumption. The internal reliability of CAGE was adequate, and in relation to alcohol consumption, there was a linear relationship between the CAGE score and both the current and previous excessive consumption. In conclusion, this study indicates good concurrent validity and adequate psychometric properties of the CAGE questionnaire. The dose-response pattern seen between the CAGE score and alcohol consumption, suggests that it can be used as an ordinal measure, rather than with a cut-off of two or more. The concurrent validity of the CAGE is better in women than in men.