There was one study done in 1975 at the Kansas City VA Medical Center that did have a control group of sorts. They were simply advised to quit drinking. If anyone has a link to the full article, I would be interested.
Abstract available
here.
J Stud Alcohol. 1977 May;38(5):1004-31.
Alcoholism: a controlled trial of "treatment" and "advice".
Edwards G, Orford J, Egert S, Guthrie S, Hawker A, Hensman C, Mitcheson M,
Oppenheimer E, Taylor C.
Two groups of alcoholics received either one counseling session or several months of in- and outpatient treatment. One year later there were no significant differences in outcome between the two groups.