The studies selected for this meta-analysis (Table 1) were published between 1973 and 2010. Most were from the United States (10), followed by India (5), Italy (2), and one each from the United Kingdom, Finland, Austria, Denmark, and Switzerland. The cumulative total of subjects analyzed in the 22 studies was 2414, ranging from 12 [13] to 605 [27]. Over half included 100 or more subjects. The subjects were alcohol dependent in 18 of the studies and diagnosed as alcohol abuse or dependent in the other four studies [14], [22], [31], [32]. For the studies indicating gender, 2058 were men and 266 were women (11.4%). The breakdown by gender was not available in a sub sample of two studies in which we analyzed only the arms of the study that were related to our research question [14], [25]. In one study, gender was not indicated [32]. Two studies evaluated adolescents (mean age 17) [33], [34], one evaluated an older population (>60 years old) [24]. The remaining studies analyzed subjects with a mean age range of 31–52 years.
