Results of the two studies identified in this systematic review offer no evidence to support alcohol screening and BI efficacy among primary-care patients with very heavy drinking or dependence. Further, the studies were of limited generalisability. Patient samples were small in both studies; one study included only women, and the other included only Mexican Americans; results were not specifically analysed by dependence; the range of outcome measures could have been greater; and, in one of the studies, the intervention was conducted by an expert.
Other evidence in the literature suggests that screening and BI has efficacy for those who drink too much but do not have dependence. It may turn out to have efficacy for those with more severe unhealthy use, but evidence to date is not available to support this. There is a difference between an absence of evidence and evidence for absence of effect: the circumstance here is the former. Regardless, it is clear that we cannot conclude, on the basis of high-quality evidence in the scientific literature, that BI among those identified by alcohol screening in primary care works for people with very heavy drinking or dependence.
This study had several limitations. Ideally, systematic reviews are conducted by at least two independent raters, and inter-rater reliability is reported. Such a process might have strengthened this paper. Second, the findings relied largely on prior systematic reviews, exclusion criteria in original articles were sometimes not clearly specified, and non-English language studies were not included. However, of the four non-English studies included in the prior systematic reviews, two excluded patients with dependence and patients who had received treatment for alcohol problems [32
], one excluded patients who had received treatment [34
], and one excluded people with heavy drinking (≥95 units per week) and failed to provide clear data on randomisation methods [35
]. As such, these studies would have either been excluded from the current review based on criteria other than language or, if included, would have appeared among the studies that excluded patients with very heavy use or dependence (and thus would not have contributed information on efficacy of BI in such patients).
One might wonder whether the BI literature beyond primary care might inform the question asked in this review. However, the context of care appears to be quite important for BI. In the literature on BI in emergency departments, most studies found no impact of BI on drinking [36
]. Severity may be an explanation for inconsistent results on BI efficacy in other settings, such as hospitals [39
]. For example, one of the few BI studies in any setting that did not exclude people with dependence found no efficacy for BI in hospitalized patients; 77% of patients in the sample had dependence, because that was the nature of the population found in the hospital [7
]. A subgroup analysis from the same study found there may have been an impact of BI on drinking among those without dependence only [41
]. Another hospital study that excluded patients with dependence or alcohol-related conditions found the effectiveness of BI for decreasing consumption was comparable to that achieved by providing a self-help booklet compared with controls who received no intervention [42
]. An additional analysis of BI in the hospital setting by Freyer-Adam et al.
] found no difference in consumption or alcohol-related consequences among the 45% of patients with dependence. Studies that compare BI to more extensive interventions could theoretically be informative, but they have generally not included people identified by screening [6
]. In such studies, BI has similar efficacy to longer interventions among those seeking help. It is not known how such results would translate to BI among people with dependence who are not necessarily seeking help.
One might consider the use of categorization of patients as having dependence a simplification of what is likely a spectrum of severity. Although it is probably true that severity of unhealthy use is on a spectrum rather than a dichotomous phenomenon, it also remains likely that, when patients are categorized as “dependent,” such categorisation includes patients with greater severity. Continuous measures of severity could be used in future studies to better identify those patients for whom BI does or does not have efficacy, but, generally speaking, studies to date have not done so.
This review has methodological strengths as well. Many systematic reviews of BI in primary care have preceded this one, making it likely that few, if any, studies have been missed. Experts in systematic-review methodology have recently encouraged the appropriate inclusion of prior systematic reviews in those that follow[44
]. This review focused on the primary-care setting as defined by the US Institute of Medicine and used a wide range of electronic databases. It also excluded studies with substantial methodological limitations.
Based on this review, it is clear that most randomised trials of alcohol BI for screen-identified patients in primary-care settings published to date have excluded patients with very heavy alcohol use or dependence. In the two studies that did include patients with dependence, the efficacy of BI for such patients remains unknown.