Alcohol and Alcoholism Advance Access originally published online on June 2, 2006
Alcohol and Alcoholism 2006 41(5):581; doi:10.1093/alcalc/agl040
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REPLY
CUNNINGHAM CONCERNING ‘REGRESSION TO THE MEAN: WHAT DOES IT MEAN?’
Author to whom correspondence should be addressed at: E-mail: kent.johnsson{at}med.lu.se
We agree that our interpretation of our results regarding a cognitive behaviour alcohol programme compared with post-mailed minimal intervention (Johnsson and Berglund, 2006
) is conservative in that we did not include the interpretations suggested by Cunningham (2006). This particularly applies to the possibility that both interventions were effective in reducing drinking.
The design we used was intended to compare a rather extensive intervention with a minimal intervention in order to compare differences in efficacy. Based on the lack of differences, we concluded that the result could be caused by regression to the mean.
We would certainly like to study an untreated control group in order to see whether the positive effects of both interventions could be related to the interventions themselves, or to Cunningham's suggestion that the positive effects could be related to spontaneous improvement.
Johnsson presented data about the natural course for the subsequent two years and reported only very small additional differences (Johnsson, 2006). The AUDIT scores for the total high-risk groups were 12.6 on admission, 10.4 at the one-year follow up, 10.2 at the two-year follow-up and 10.0 at the three-year follow-up. Consequently, a natural course showing a trend towards reduced drinking through the college years is probably not the main cause of the decrease.
If both interventions in our study have positive effects, this has important practical implications concerning their usefulness. Walters et al. (2000) reported results from a study in which they compared a 2 h information and motivation session plus mailed feedback with mailed feedback only or no treatment. At the 6 week follow-up, the feedback-only group significantly decreased its alcohol consumption compared with control. In comparison with the full treatment condition, the feedback group decreased its alcohol consumption more, but not significantly. This study partly supports the possibility that our two interventions both have positive effects.
REFERENCES
Cunningham, J. A. (2006) Regression to the mean: what does it mean? Alcohol and Alcoholism 41, 580.
Johnsson, K. O. (2006) Alcohol intervention studies in university students. Randomised controlled trials of responsible beverage service and high-risk drinking. Clinical Alcohol Research, Department of Health Sciences, Lund University, Faculty of Medicine, Doctoral Dissertation Series 2006:55.
Johnsson, K. O. and Berglund, M. (2006) Comparison between a cognitive behavioural alcohol programme and post-mailed minimal intervention in high-risk drinking university freshmen: results from a randomized controlled trial. Alcohol and Alcoholism 41, 174–180.
Walters, S. T., Bennett, M. E. and Miller, J. H. (2000) Reducing alcohol use in college students: a controlled trial of two brief interventions. Journal of Drug Education 30, 361–372.[CrossRef][Web of Science][Medline]
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