Anne Moyer, John W. Finney, Carolyn E. Swearingen & Pamela Vergun

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1 REVIEW Brief interventions for alcohol problems: a meta-analytic review of controlled investigations in treatment-seeking and non-treatment-seeking populations Anne Moyer, John W. Finney, Carolyn E. Swearingen & Pamela Vergun Center for Health Care Evaluation,VA Palo Alto Health Care System and Stanford University Medical Center, Menlo Park, CA, USA Correspondence to: Anne Moyer PhD Department of Psychology SUNY Stony Brook Stony Brook, NY USA Tel: Fax: [email protected] Submitted 6 February 2001; initial review completed 3 July 2001; final version accepted 6 August 2001 ABSTRACT Brief interventions for alcohol use disorders have been the focus of considerable research. In this meta-analytic review, we considered studies comparing brief interventions with either control or extended treatment conditions. We calculated the effect sizes for multiple drinking-related outcomes at multiple follow-up points, and took into account the critical distinction between treatment-seeking and non-treatment-seeking samples. Most investigations fell into one of two types: those comparing brief interventions with control conditions in non-treatment-seeking samples (n = 34) and those comparing brief interventions with extended treatment in treatment-seeking samples (n = 20). For studies of the first type, small to medium aggregate effect sizes in favor of brief interventions emerged across different follow-up points. At follow-up after >3 6 months, the effect for brief interventions compared to control conditions was significantly larger when individuals with more severe alcohol problems were excluded. For studies of the second type, the effect sizes were largely not significantly different from zero. This review summarizes additional positive evidence for brief interventions compared to control conditions typically delivered by health-care professionals to non-treatment-seeking samples. The results concur with previous reviews that found little difference between brief and extended treatment conditions. Because the evidence regarding brief interventions comes from different types of investigation with different samples, generalizations should be restricted to the populations, treatment characteristics and contexts represented in those studies. KEYWORDS Alcohol problems, brief interventions, treatment. INTRODUCTION Brief interventions for alcohol use disorders have been the focus of considerable research over the past three decades. This enthusiasm stems from the frequently cited advantages of brief interventions: they are more likely to be acceptable to individuals with less severe drinking problems than more intensive treatments, can be administered by a wider variety of providers in a wider range of clinical settings and are less expensive (Heather 1986; Effective Health Care Team 1993). Reflecting this growing interest, a small number of reviews of brief intervention trials have used metaanalytic techniques to summarize the results. These reviews have generally focused on particular subsets of the brief intervention research literature (e.g. interventions delivered in primary care settings, investigations

2 280 Anne Moyer et al. assessing particular outcome variables), and have indicated positive support for brief interventions. For example, Wilk et al. (1997) reviewed eight randomized controlled trials of brief interventions. They focused on studies with adult participants and total sample sizes greater than 30. The overall odds-ratio for the proportion of participants drinking moderately 6 or 12 months post-intervention was 1.91 (95% confidence interval = ) in favor of brief interventions, with no significant heterogeneity in odds ratios across studies. Pooling the six higher-quality trials produced a similar overall odds-ratio, also with no significant heterogeneity. Subgroup analyses showed trends for a greater likelihood of moderate drinking following interventions with more than one session versus that following just one session, for females versus males, and for interventions delivered in inpatient versus outpatient medical settings. However, as suggested by the homogeneity of odds ratios, none of these comparisons was significant at the p < 0.05 level. As part of a larger overview of the brief intervention literature, the Effective Health Care Team (1993) quantitatively summarized the results of six trials, focusing on studies that were comparable in terms of type of intervention, setting and population, and that contrasted a brief intervention with an assessment-only control group. The results of these trials were also generally consistent and the overall effect for brief interventions was estimated to be a 24% greater reduction in alcohol consumption relative to control conditions (95% confidence interval = 18 31% reduction). Concentrating on brief interventions delivered to primary health-care populations, Poikolainen (1999) examined seven studies that randomly assigned participants to intervention and control groups and had followups of 6 12 months. Studies with participants recruited from hospital wards or including highly alcoholdependent individuals were excluded. The findings indicated that very brief (5 20 minutes) interventions had significant effect sizes relative to control conditions for alcohol consumption (-70 g/week) and gammaglutamyltransferase (GGT) activity (-9.4 units/l), but the estimates were not homogeneous. Extended (several visits) brief interventions had significant effect sizes for alcohol consumption (-65 g/week) but not for GGT activity, and the effect sizes for both outcomes lacked statistical homogeneity. One significant homogenous effect favored extended brief interventions for alcohol consumption in female samples (-51 g/week), but it was based on the results of only two studies. In the review most similar to the present one, Bien, Miller & Tonigan (1993) pooled the findings of 18 studies comparing brief interventions with a control condition, and 13 studies comparing brief interventions with more extended therapy. Effect sizes were calculated for the amount of alcohol consumed, or for other outcome variables such as days since last drink or percentage of heavy drinking days if data on alcohol consumption were not available. The mean pooled effect size for brief interventions versus a control condition moderately favored brief interventions (0.38), whereas the mean pooled effect size for brief interventions versus extended treatment was negligible (0.06). However, these mean effect sizes were not weighted by study size/variance, and no homogeneity tests or significance tests for overall effect sizes were conducted. A challenge in summarizing the research literature on the effects of brief interventions stems from varying definitions of such interventions used in different studies (Jönson et al. 1995; Maisto et al. 1999). As the term suggests, one defining characteristic of brief interventions is their length. For example, Babor (1994) terms one contact as minimal, one to three sessions as brief, five to seven sessions as moderate and eight or more sessions as intensive treatment. Occasionally, however, what is considered a brief intervention in one study is considered an extended intervention in another (Jönson et al. 1995). Other features sometimes used to characterize brief interventions include: (1) having a goal of reduced or non-problem drinking as opposed to abstinence; (2) being delivered by a physician or other health-care professional as opposed to an addiction specialist; (3) being directed at non-dependent drinkers as opposed to dependent drinkers; (4) addressing individuals level of motivation to change drinking habits; (5) being self- (as opposed to professionally) directed, and/or (6) having particular ingredients, summarized by the acronym FRAMES (Feedback of risk, encouraging Responsibility for change, Advice, a Menu of options, therapeutic Empathy, and enhancing Self-efficacy; Miller & Rollnick 1991). Due to this variation, some reviews and metaanalyses in this area have been criticized for referencing studies selectively or not distinguishing among different types of brief interventions (Heather 1995; Drummond 1997). Heather (1995, 1996) argued that two broad types of brief interventions should be considered separately. The first type, opportunistic or primary care brief interventions, is made up of interventions typically designed for and evaluated among individuals not seeking alcohol treatment who are identified by opportunistic screening in primary care settings. Such individuals often have less severe alcohol problems and lower motivation for treatment. These interventions are typically shorter, less structured, less theoretically based and delivered by a nonspecialist. Heather notes that the second type, specialist brief interventions, originated as a control condition in evaluations of traditional treatment and has typically

3 Brief interventions for alcohol problems 281 been evaluated among individuals persuaded or mandated to seek treatment for alcohol-related problems. These interventions are usually longer, more structured, theoretically based and delivered by a specialist. Heather (1989) also noted that evidence regarding the effectiveness of these two types of brief intervention stems from different research designs. Studies examining opportunistic or primary care brief interventions typically compare them to a no-treatment control condition, whereas studies examining specialist brief interventions typically compare them to traditional, more extended treatments. For such comparisons of brief interventions with traditional treatment, a difficulty has been proving the null hypothesis (Heather 1989), as the absence of statistically significant differences does not necessarily prove equal efficacy (Mattick & Jarvis 1994), especially with small sample sizes. An alternative to significance testing in individual studies, which may mask small but meaningful effects (Rosenthal 1991), is pooling effect size indices over a large number of studies. This meta-analytic approach provides a more powerful estimate of how brief interventions perform. On the other hand, it has been argued that underpowered studies with small sample sizes should not be included in pooled analyses of effect sizes because they may lead to upwardly biased estimates of intervention (Kraemer et al. 1998). Here, we provide a meta-analytic review that includes more recent work in this area. We take a broad view of the literature investigating brief interventions by considering comparisons of brief interventions with both control conditions and extended treatment, and by summarizing effects across different categories of drinkingrelated outcomes (i.e. alcohol consumption, abstinence rates, physiological indices) at multiple follow-up points. We present aggregate effect sizes, including both all available studies and only adequately powered studies. We also take into account the critical distinction between non-treatment-seeking samples identified opportunistically (in settings where individuals attend for reasons unconnected with drinking problems) and treatmentseeking samples who attend specialist treatment (in settings where individuals present themselves or are mandated to seek help for drinking problems). Examining such studies separately allows us to determine to what extent results are generalizable across treatment-seeking and non-treatment-seeking populations. In addition, where significant heterogeneity among effect sizes is found for a given outcome, indicating systematic variation as opposed to that due to sampling error, we examine whether certain study characteristics could explain such variation. The question of whether brief interventions are more effective for persons with less severe alcohol problems and less effective in more severe cases has been identified as a critical research issue (Bien et al. 1993), because it pertains to the populations to which findings can be generalized. Thus, we determine whether studies that excluded individuals with more severe alcohol problems and those that did not produce differential findings. Also, although there is little theoretical basis for expecting gender differences in the effectiveness of brief interventions, some reviews have suggested that men are more likely than women to respond to such interventions (Anderson 1993; Bien et al. 1993) or that men respond only to brief intervention conditions whereas women may respond to both treatment and control conditions (Babor 1994). Therefore, where possible, we present effect sizes separately for men and women in order to summarize results on gender as a possible moderator of the effectiveness of brief interventions. METHODS Identification and selection of studies Studies included in this review were drawn from three sources: (1) a database of studies investigating treatment for alcohol use disorders spanning the years (Moyer et al. 2001); (2) bibliographic database searches using relevant terms such as brief intervention, early intervention, physician intervention, secondary prevention, alcoholism, problem drinkers, heavy drinkers and non-problem drinking, and (3) citations in previous reviews and primary reports. We strove to include studies based on a definition of a brief intervention that was as consistent and concrete as possible, while being cognizant of the variety of characteristics that have been implicitly or explicitly considered to be components of such treatment. Following Babor s (1994) definition, we included studies of interventions providing no more than four sessions. However, data from one potentially slightly longer intervention were included. Kristensen et al. s (1983) intervention involved a single session of feedback and advice followed by physician consultations every 3 months, monthly GGT tests and monthly nurse contacts. Although the distinction between intervention versus follow-up data collection was ambiguous, we followed the lead of other reviewers who have considered this an important study in the area (Effective Health Care Team 1993; Bien & Miller 1995; Wilk et al. 1997) and have defended its inclusion in prior reviews (Bien & Miller 1995). Because the amount of contact time is sometimes difficult to estimate from the information provided in published reports, we were unable to use this parameter as a criterion for inclusion. Some interventions involved no contact with a provider, but consisted solely of written self-help

4 282 Anne Moyer et al. materials such as manuals, workbooks, booklets or letters. Because many brief interventions supplement their advice and counseling with such resources, and because researchers in this area maintain that self-help is an integral part of brief interventions (Heather 1986, 1989), we included studies of such written materials (bibliotherapy), despite the fact that it is not clear how brief these interventions were. Some brief interventions are directed at motivating individuals to accept referral to more extensive treatment. Although these differ from brief interventions that address drinking directly, they are similar in motivational content to many of those interventions. Accordingly, we included studies of this type of intervention if reports focused on at least one drinking-related outcome, as opposed to simply treatment seeking. Conversely, we did not include studies of brief interventions designed to encourage pregnant women to abstain from alcohol, as individuals in these samples are not necessarily drinking at levels conventionally considered harmful, apart from potential harm to the foetus. We classified studies according to both the type of comparison (brief intervention versus a control or versus a more extended treatment) and the type of patient population (treatment-seeking versus non-treatmentseeking). We considered individuals who responded to advertisements or who were referred to alcohol treatment to be treatment-seeking, and individuals who were identified opportunistically when being treated for other problems in health-care settings to be non-treatment-seeking. Calculation and combination of treatment effect sizes Standardized mean difference effect size estimates were calculated with the assistance of two software packages capable of using different types of information available from published reports (DSTAT: Software for the Meta- Analytic Review of Research Literatures, Johnson 1989; ES: A Computer Program for Effect Size Calculation, Shadish, Robinson & Lu 1999). We used the effect size estimate (d), which corrects for small sample size bias (Hedges & Olkin 1985). It is the difference in group posttest means for a given outcome variable divided by the pooled standard deviation of the two groups, multiplied by the correction factor 1 [3/(4n 9)], where n equals the total number of participants. Whenever possible, follow-up means and standard deviations or the proportions of individuals falling into dichotomous categories at follow-up were used. If this information was not available, but statistical information was presented, we used conversions yielding effect size estimates algebraically equivalent to follow-up standardized mean differences (Shadish et al. 1999). If study results were only described as, or could be inferred to be, non-significant, an effect size of zero was assigned; if results were only described as significant, a p < 0.05 significance level was assumed, and the corresponding effect size was calculated (Rosenthal 1995). Such approximations were used to calculate 13% of the effect sizes. Effect sizes were estimated by one rater (C.S.), who abstracted information from study reports and performed computations. Another rater (A.M.) reviewed the abstractions and computations for accuracy. Effect sizes were calculated for multiple types of drinking-related outcome variables, when available. These included: (1) alcohol consumption, quantitybased; (2) alcohol consumption, time-based; (3) the proportion of participants abstinent; (4) the length of time over which participants were abstinent; (5) the proportion of participants drinking without problems; (6) the length of time over which participants drank without problems; (7) the frequency with which participants were intoxicated ; (8) physiological markers of alcohol use or abuse, such as GGT activity; (9) global ratings of severity of drinking problems; (10) ratings of improvement in drinking; (11) the presence of dependence symptoms, and (12) problems in multiple life areas resulting from drinking. To provide a broad index of outcome across the largest possible number of studies, all drinking-related outcomes for a particular study were aggregated. To provide a more specific index of outcome comparable across (fewer) studies, outcomes related to alcohol consumption only were aggregated. Inverse-variance-weighted aggregate effect sizes were computed with the Comprehensive Meta-Analysis software program (Borenstein, Rothstein & Cohen 1998). To ensure that effect sizes included in pooled estimates were independent, the mean effect size was used where there was more than one effect size at a specific follow-up point (Rosenthal & Rubin 1986). For investigations that had multiple treatment groups, a single condition was chosen for the analyses. For studies including multiple brief interventions, the briefest of the conditions was selected. For studies including multiple extended treatments, we chose the most typical of the extended treatment conditions (i.e. the one that was the most similar to the extended treatment conditions of the other studies included in our review, in terms of modality and/or setting). We included follow-up points of up to 24 months, thereby excluding results for longer follow-ups of years in five studies. However, all five studies reported outcomes at earlier points that were included in the analyses. In addition to aggregating effect sizes for all eligible studies, we also summarized effect sizes for only those studies with adequate power to detect a medium effect size (Kraemer et al. 1998). Excluding underpowered studies from meta-analytic reviews is a method to elimi-

5 Brief interventions for alcohol problems 283 Table 1 Aggregate effect sizes for brief intervention versus control conditions in non-treatment-seeking samples. Heterogeneity Outcome Number of samples Effect size a 95% confidence interval Q df p Composite of all drinking-related outcomes 3 months ** 0.082, >3 6 months *** 0.081, >6 12 months *** 0.184, >12 months , Alcohol consumption 3 months *** 0.392, >3 6 months *** 0.098, >6 12 months *** 0.203, >12 months , a Positive values for effect sizes indicate better outcome for brief intervention conditions compared to control conditions. ** P < 0.01; *** P < nate potentially misleading research conclusions by removing bias due to the file drawer problem (Rosenthal 1991). To the extent that underpowered studies with significant findings are more likely to be published than underpowered studies with non-significant findings (left in a file drawer ), including underpowered studies tends to upwardly bias intervention effect size estimates. Focusing only on studies with sufficient statistical power provides a less biased estimate of intervention effects. RESULTS Our literature search yielded an initial group of 92 studies that reported outcomes of brief interventions. Of these, 36 were excluded because they examined a treatment that did not meet our definition of brief, were single-group studies, compared only multiple brief intervention conditions without a control or an extended treatment condition, did not report results for participants with alcohol use disorders separately from those with other substance use disorders, and/or focused on samples of pregnant women. The final sample of 56 investigations consisted of two studies comparing brief interventions to control conditions in treatment-seeking samples, 34 comparing brief interventions to control conditions in non-treatmentseeking samples, 20 comparing brief interventions to more extended treatments in treatment-seeking samples, and one comparing a brief intervention to more extended treatment in a non-treatment-seeking sample (a table describing the characteristics of these 56 studies and the effect sizes calculated for each study is available from the authors). One report (Chapman & Huygens 1988) contributed to both the brief intervention versus control and brief intervention versus extended treatment comparisons. Seventy-nine percent (27) of the 34 brief intervention versus control, non-treatment-seeking sample studies excluded participants who met diagnostic criteria for, or showed signs of, alcohol dependence, drank at high levels or for a long period of time, and/or had been treated previously for alcohol problems, whereas 50% (10) of the 20 brief intervention versus extended treatment in treatment-seeking samples studies excluded such individuals. This pattern is consistent with Heather s (1995, 1996) observation that the literature comprises two distinct types of studies and that studies comparing brief interventions to a control condition tend to include persons with less severe problems. Because only two investigations (Chapman & Huygens 1988; Miller, Benefield & Tonigan 1993) compared a brief intervention versus a control condition in a treatmentseeking sample, they could not be usefully combined meta-analytically. The limited evidence they provide indicates small-to-moderate effect sizes favoring the brief interventions. The single investigation (Swenson et al. 1981) of a brief intervention (a court-mandated homestudy course) versus extended treatment (a series of driving while intoxicated therapy workshops) in a nontreatment-seeking sample reported its results only as non-significant. We present inverse-variance-weighted aggregate effect sizes for the two main types of comparisons: (1) brief interventions versus control conditions in nontreatment-seeking samples, and (2) brief interventions versus more extended treatments in treatment-seeking samples. Tables 1 and 2 present the aggregate effect sizes and heterogeneity statistics for: (1) the composite of all drinking-related outcomes assessed, and (2) the quantity of alcohol consumed at one or more of four follow-up

6 284 Anne Moyer et al. Table 2 Aggregate effect sizes for brief intervention versus extended treatment conditions in treatment-seeking samples. Heterogeneity Outcome Number of samples Effect size a 95% confidence interval Q df p Composite of all drinking-related outcomes 3 months , >3 6 months , >6 12 months , >12 months , Alcohol consumption 3 months , >3 6 months ** 0.119, >6 12 months , >12 months , a Positive values for effect sizes indicate better outcomes for extended treatment conditions compared to brief intervention conditions. ** P < points ( 3 months, >3 6 months, >6 12 months and >12 months) for each of the two types of study. Figures 1 4 illustrate the study level effect sizes (and their 95% confidence intervals) contributing to the aggregate effect sizes for each of the two types of studies for each of the two outcome variables. Table 1 indicates that for comparisons of brief interventions versus control conditions, the effect sizes were significantly different from zero at the 3 month, >3 6 month and >6 12 month follow-up points for both the composite of all drinking-related outcomes and for alcohol consumption. The aggregate effect size at each of the three points indicated superior outcomes for brief intervention conditions. These effect sizes ranged from 0.14 to 0.67 (small to medium, Cohen 1988), with the largest effect occurring for alcohol consumption at the earliest ( 3 month) follow-up point. With the exception of alcohol consumption at the >3 6 and >6 12 month follow-up points, all effect sizes were statistically homogenous, indicating that variation did not exceed what would be expected from sampling error alone. Thus, there was no variation on which to probe the effects of different study features. For the two follow-up points with significant heterogeneity in alcohol consumption effect sizes, we tested whether the exclusion of more alcoholdependent individuals in some studies could explain this variability. This was the case only for the >3 6 month follow-up point, with a significant ANOVA analogue fit statistic (Q = 5.75, p < 0.05). The effect for brief interventions compared to control conditions was significantly larger when individuals with more severe alcohol problems were excluded (0.211, 95% confidence interval = ) than when they were not excluded (0.046, 95% confidence interval = to 0.158). Note that when individuals with more severe alcohol problems were excluded the pooled effect size was significantly different from zero, whereas when such individuals were not excluded, the effect size was not significantly different from zero. There was no remaining heterogeneity in effect sizes once the variability explained by the exclusion of individuals with more severe problems was taken into account. Table 2 indicates that, with the exception of alcohol consumption at the >3 6 month follow-up, aggregate effect sizes for comparisons of brief intervention conditions versus more extended treatments were not significantly different from zero. For the >3 6 month follow-up, extended treatments were superior to brief interventions in reducing the quantity of alcohol consumed, with a significant small-to-medium combined effect size of Effect sizes for each of the four follow-up points for both outcomes were statistically homogeneous, so there was no variation to be accounted for by whether or not individuals with more severe alcohol problems had been excluded. We also examined the aggregate effect sizes only for studies with adequate power (0.80 probability) to detect a medium-sized effect (0.50), at the p < 0.05 level, based on a two-tailed t-test (n = 23 per group, if cell sizes are equal). For studies comparing a brief intervention condition to a control condition, 25 out of the 34 studies originally selected had adequate power. In this smaller group of studies, the results for aggregate effect sizes for both the composite of all drinking-related outcomes and for alcohol consumption were similar to that found with the larger group of 34 studies (significant d = , p < ). For the seven adequately powered studies comparing a brief intervention condition to an extended treatment condition, the aggregate effect sizes also were similar to those found for the larger group of 20 studies

7 Brief interventions for alcohol problems 285 Acuda 1992 Anderson & Scott 1992 Antti-Poika 1988 Babor et al Boyadjieva 1992 Chick et al Dimeff et al Elvy et al Fleming et al Fleming et al Gentilello et al Heather et al Heather et al Ivanets et al Kristenson et al Kuchipudi et al Logsdon et al Machona 1992 Maheswaran et al Marlatt et al Nilssen et al Ockene et al Richmond et al Richmond et al Rollnick et al Saunders et al Scott & Anderson 1990 Senft et al Serrano et al Skutle 1992 Tomson et al Wallace et al Watson et al Welte et al Mean months >3 6 months >6 12 months >12 months Figure 1 Effect sizes and 95% confidence intervals for brief intervention versus control conditions, composite outcome (a significant effect only at >3 6 months, d = 0.625, p < 0.01). Thus, we conclude that the results for the larger samples would not be changed by taking into account negative results from unpublished studies. We also calculated aggregate effect sizes by gender for the two main types of studies at follow up point(s) where sufficient data were available (>3 6 and >6 12 months, and 3 months, for brief intervention versus control condition studies and brief intervention versus extended treatment studies, respectively). For the small number of investigations that provided such data (eight and three, respectively), there was no significant heterogeneity among the effect sizes for males and females at any followup period (Q = , p = ), indicating no systematic variation that could be attributed to gender. DISCUSSION In this meta-analytic review of trials of brief interventions, we considered a range of drinking-related outcomes and distinguished between investigations that compared brief interventions to control conditions, and investigations that compared brief interventions to more extended treatments. The first type of investigation included non-treatment-seeking samples and was more likely to exclude individuals with more severe alcoholrelated problems, whereas the second type of investigation recruited participants from individuals referred to or presenting for alcohol treatment and was less likely to exclude more severely affected individuals. Because the evidence regarding brief interventions comes from different types of investigation with different samples (Heather 1995, 1996), generalizations should be restricted to the populations, treatment characteristics and contexts represented in those studies. Brief interventions versus control conditions in non-treatment-seeking populations The significant, largely homogenous, small-to-medium aggregate effect sizes we found for 34 studies comparing brief interventions to control conditions offer additional positive evidence for brief interventions to that presented in previous, smaller, more focused meta-analytic reviews (Bien et al. 1993; Effective Health Care Team 1993; Wilk et al. 1997). The effect sizes identified were in the smallto-medium range. Using the binomial effect size display

8 286 Anne Moyer et al. Acuda 1992 Anderson & Scott 1992 Antti-Poika 1988 Babor et al Boyadjieva 1992 Chick et al Dimeff et al Elvy et al Fleming et al Fleming et al Gentilello et al Heather et al Heather et al Ivanets et al Kristenson et al Kuchipudi et al Logsdon et al Machona 1992 Maheswaran et al Marlatt et al Nilssen et al Ockene et al Richmond et al Richmond et al Rollnick et al Saunders et al Scott & Anderson 1990 Senft et al Serrano et al Skutle 1992 Tomson et al Wallace et al Watson et al Welte et al Mean months >3 6 months >6 12 months >12 months Figure 2 Effect sizes and 95% confidence intervals for brief intervention versus control conditions, alcohol consumption (BESD, Rosenthal 1994), a small effect size (0.20) in favor of brief interventions translates into 55% of individuals treated with brief interventions falling above the median on a given outcome compared to only 45% of individuals in the control condition; a medium effect size (0.50) in favor of brief interventions translates into corresponding percentages of 62 and 38%. Effect sizes were largest at the earliest follow-up points, suggesting decay in intervention effects over time. In addition, because only five of the 34 studies in this group had follow-ups of greater than 1 year, we know little about the longer-term effects of such brief interventions. Thus, to enhance the effectiveness of these interventions, health-care providers should provide ongoing monitoring of patients drinking behavior and intervene appropriately if drinking becomes hazardous (Stout et al. 1999). Because these investigations included participants identified opportunistically and the majority (79%) excluded individuals with severe alcohol problems, such findings are applicable only to similar kinds of brief interventions administered to similar populations. Such individuals are not seeking treatment for alcohol-related problems, but they are often detected due to a health problem such as trauma or an elevated physiological index (e.g. GGT activity) that can be linked to excessive alcohol consumption. The linkage of drinking to health problems, coupled with advice provided by a physician or nurse, may account (at least partially) for the positive effects of brief interventions in non-treatment-seeking populations. For the level of alcohol consumption assessed at one follow-up period (>3 6 months), heterogeneity among the effect sizes was fully accounted for by whether or not individuals with more severe alcohol problems were excluded. Brief interventions were more effective compared to control conditions in studies where more severely affected individuals were excluded; brief interventions were not more effective than control conditions in studies where more severely affected persons were not excluded. This finding suggests that, at least during this period in the post-treatment course, such interventions which usually consist of a single session of advice, often accompanied by feedback and delivered in a health-care setting are useful only for patients with less severe drinking problems. Although we focused on this one potential moderator, other client characteristics, such as level of motivation (Bien et al. 1993), should also be

9 Brief interventions for alcohol problems 287 Baer et al Chapman & Huygens 1988 Chick et al Drummond et al Duckert et al Edwards et al Harris & Miller 1990 Hartman et al Miller et al. 1980, 83, 92 Miller et al. 1980, 83, 92 Miller et al Montero 1992 P. M. R. G. 1997, 98 Robertson et al Sanchez-Craig et al Sanchez-Craig et al Sannibale 1989 Skutle et al Sitharthan et al Zweben et al Mean months >3 6 months >6 12 months >12 months Figure 3 Effect sizes and 95% confidence intervals for brief intervention versus extended treatment conditions, composite outcome examined as moderators of intervention effects in future analyses. Brief interventions versus extended treatment in treatment-seeking populations For the most part, the effects for investigations comparing brief interventions to more extended treatments were statistically homogeneous and not significantly different from zero. We found that extended treatments were superior to brief interventions in reducing alcohol consumption only at the >3 6 month follow-up period, with a small-to-medium (0.42) effect size on one of the two outcomes examined in the three studies with such followups. Thus, although one significant effect size favoring extended treatment conditions emerged, overall, our results are consistent with the 0.06 effect size reported in the review by Bien et al. (1993). The fact that these results are effect sizes aggregated over a number of studies and time points limits the possibility that small but meaningful effects were overlooked. For this group of studies, there was no significant heterogeneity among the effect sizes at any follow-up point for either outcome variable. Thus, examining the effects of moderator variables, such as whether individuals with more severe alcohol problems were excluded, was precluded. Another potential moderator variable that would have been interesting to consider is the method by which participants were recruited, as it is conceivable that those who responded to advertisements had less severe alcohol problems than those referred to or mandated to treatment. It is possible that, although there was no significant heterogeneity among effect sizes, various moderators did influence outcomes in complex interactive ways. Thus, their effects may have worked against each other, resulting in similar results across studies. Because these findings could be used to shape healthcare policy, it is important to describe how the brief interventions in these studies differed from those in studies of non-treatment-seeking individuals. Firstly, as Heather (1995, 1996) suggested, the treatment providers tended to be therapists or counselors, not general health-care providers. Secondly, the brief interventions tended to be more intensive/extensive than those provided to nontreatment-seeking patients. At first glance, the six brief interventions that were self-directed and consisted of treatment manuals given to patients might seem even more minimal than brief advice from a physician or

10 288 Anne Moyer et al. Baer et al Chapman & Huygens 1988 Chick et al Drummond et al Duckert et al Edwards et al Harris & Miller 1990 Hartman et al Miller et al. 1980, 83, 92 Miller et al. 1980, 83, 92 Miller et al Montero 1992 P. M. R. G. 1997, 98 Robertson et al Sanchez-Craig et al Sanchez-Craig et al Sannibale 1989 Skutle et al Sitharthan et al Zweben et al Mean months >3 6 months >6 12 months >12 months Figure 4 Effect sizes and 95% confidence intervals for brief intervention versus extended treatment conditions, alcohol consumption nurse. However, if studied carefully, bibliotherapeutic materials may demand a considerable amount of time. In addition, manuals included in these investigations often described theoretically derived behavior-change strategies that could be more specific and perhaps more helpful than the face-to-face encouragement or advice often provided to non-treatment-seeking patients. Bibliotherapy may be especially attractive to individuals who are reluctant to enter treatment because of concerns about breach of privacy, stigma or other adverse consequences (Duckert 1988). In many of the studies comparing brief interventions to more extended treatments, the contrasted treatment conditions were not as different as might be implied from their labels. For instance, although the motivational enhancement therapy condition in Project MATCH (Project MATCH Research Group 1997, 1998) consisted of only four sessions, those sessions were spread over a 12 week period, the same period over which weekly extended treatment was provided. In addition, the motivational enhancement therapy actually delivered (as opposed to prescribed) consisted of an average of 3.2 sessions, whereas the two extended treatments consisted of 7.5 and 8.3 sessions, on average (Carroll et al. 1998). Moreover, participants in all conditions underwent considerable pre-treatment assessment and regular followups at 3 month intervals, both of which may have a therapeutic or motivational effect (Edwards et al. 1977; Sobell & Sobell 1980; Jönson et al. 1995; Ogborne & Annis 1998). Although Chapman & Huygens (1988) compared a single confrontational interview plus referral to community services to a much more extensive outpatient program that met twice weekly for 6 weeks, both groups had undergone 2 weeks of inpatient detoxification prior to group assignment, diminishing the treatment differences between the conditions. Drummond et al. (1990) compared care by a general practitioner (GP), after initial counseling and advice, to care by a specialist clinic. Specialists remained involved in the treatment of participants in the GP care condition by offering further advice and support to the GP. Furthermore, 18% of the participants in the GP care group attended specialist clinics during follow-up. Similarly, Chick et al. s (1988) brief advice condition received additional attention from other sources, or from the investigators themselves, for com-

11 Brief interventions for alcohol problems 289 passionate reasons. Duckert et al. (1992) compared individual counseling with group therapy that differed primarily with respect to the number of therapeutic meetings and the presence/absence of other group members. However, both treatments were based on social learning theory and participants in both conditions received information on self-control training and were given advice about how to attain their abstinence or reduction-in-drinking goal. Finally, as has been noted previously (Mattick & Jarvis 1994), participants in the brief-advice-only condition of Edwards et al. (1977) sought help from other treatment agencies, had a considerable number of visits to their general practitioners and underwent repeated assessments, whereas a proportion of the intensive treatment group had fairly minimal contact. Indeed, Monahan & Finney (1996) estimated that participants in the advice condition had received an average of 30 hours of treatment, considerably more than would be implied by the term brief intervention, but certainly less than that received by individuals in the extended condition (97 hours, on average, per patient). In short, participants in many of the brief interventions that have been compared to more extensive treatment conditions have been exposed to treatments that strain the meaning of brief and are not as dramatically different from the extended treatments against which they were compared as one might imagine simply from condition labels. Hjalmarsson & Rehnmen 2000). However, that such treatments could reach a considerable proportion of individuals with alcohol problems who would not otherwise seek formal help (Rumpf et al. 1998) is not in question. Because their effects relative to control conditions diminish with time, health-care systems need to develop methods for monitoring patients subsequent drinking and to refer patients to specialized treatment, as needed, at a later point (Stout et al. 1999). In addition, this review indicated little difference in the effects of brief intervention and extended treatments. However, because the group of studies that has compared brief interventions to extended treatments has often contrasted treatment conditions that are not extremely different, wholesale replacement of specialist, extended approaches to treatment with considerably briefer interventions for these populations is not warranted. It is also important that enthusiasm for brief interventions does not divert attention from promising specialist treatment approaches (Drummond 1997). However, the results of this review do suggest that brief interventions can be successful in particular settings with selected individuals. For instance, in treatment-seeking, more alcoholdependent populations, brief interventions may be appropriate as an initial treatment. Those patients who do not respond to such interventions can be referred to more intensive/extensive treatment, in a stepped care approach (Breslin et al. 1998; Fleming & Manwell 1999). Gender and brief intervention effects Although it was possible to aggregate effect sizes by gender for only a small number of studies belonging to the two main types of study, we found no evidence that men or women benefit more from brief interventions. This no-difference finding may partly be due to the lack of more specific, theoretically based hypotheses regarding gender differences in response to brief interventions. It is possible, for instance, that men and women might benefit from different specific types of brief intervention, such as self-directed brief interventions, or motivational as opposed to confrontational interventions. CONCLUSIONS Overall, this review provides further positive evidence for brief interventions compared to control conditions in opportunistic samples and as typically delivered by health-care professionals. The extent to which healthcare professionals are receptive to, or are qualified for delivering, such interventions effectively has been debated (Roche et al. 1991; Bradley et al. 1995; Rollnick, Butler & Hodgson 1997; Kaner et al. 1999; Andréasson, ACKNOWLEDGEMENTS This work was supported by National Institute on Alcohol Abuse and Alcoholism grant AA08689, the VA Quality Enhancement Research Initiative and the VA Mental Health Strategic Healthcare Group. The views expressed in this article are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs. We are grateful to Aman Bhandari, Keith Humphreys, John McKellar, Rudolf Moos, Jennifer Ritcher and Eric Stewart for helpful comments on an earlier version of this manuscript. 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