Issue of statistical power in comparative evaluations of minimal and intensive controlled drinking interventions (original) (raw)
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The effects on mortality of brief interventions for problem drinking: a meta-analysis
Addiction, 2004
Aims Brief interventions for problem drinking may result in decreased mortality rates. Long-term follow-up studies of brief interventions do not produce a clear answer to the question as to whether these interventions reduce mortality or not.Methods We conducted a meta-analysis of randomized studies comparing brief interventions with a control group, using the fixed-effects model. A systematic literature search produced four studies in which the mortality status of subjects was verified at follow-up. Six more studies reported some deaths at follow-up but did not verify mortality in death registers, and 22 further studies did not report the mortality status of the included subjects.Findings The pooled relative risk (RR) of dying was 0.47 for the four studies with verified mortality rates (95% CI: 0.25, 0.89). The pooled RR of all 32 studies was comparable (RR = 0.57; 95% CI: 0.38, 0.84), as were the RRs of several other subsamples of studies. The prevented fraction was 0.33 in the studies with verified mortality rates.Conclusions Although the overall death rate was low in the population of problem drinkers, brief interventions do appear to reduce mortality.
The efficacy-effectiveness distinction in trials of alcohol brief intervention
Addiction science & clinical practice, 2014
Three recent sets of null findings from trials of alcohol brief intervention (BI) have been disappointing to those who wish to see a reduction in alcohol-related harm through the widespread dissemination of BI. Saitz (7) has suggested that these null findings result from a failure to translate the effects of BI seen in efficacy trials, which are thought to contribute mainly to the beneficial effects of BI shown in meta-analyses, to effectiveness trials conducted in real-world clinical practice. The present article aims to: (i) clarify the meaning of the terms "efficacy" and "effectiveness" and other related concepts; (ii) review the method and findings on efficacy-effectiveness measurement in the 2007 Cochrane Review by Kaner and colleagues; and (iii) make suggestions for further research in this area. Conclusions are: 1) to avoid further confusion, terms such as "efficacy trial", "effectiveness trial", "clinical representativeness",...
Methodological and Statistical Considerations in Measuring Alcohol Treatment Effects
Alcoholism: Clinical & Experimental Research, 2003
This article addresses the design and selection of outcome methods for treatment research from a statistical perspective. Two of the major statistical and methodological issues relevant to the selection of dependent variable(s) are statistical power and social utility. Power is the paramount issue in research design. Power can be improved by measures and methods tailored to the predicted effects of treatment. These effects should vary from treatment to treatment, suggesting that no single outcome measure is suitable for all purposes. In estimating power, researchers should also consider the time-varying nature of most types of treatment effects. Given these considerations, timeline procedures have advantages because they allow the derivation of measures linked to specific treatment components. They also permit the study of time-varying effects of variables such as life stress. An analysis on the relationship between drinking and self-reported stress is presented as an illustration of how advanced statistical methods, in conjunction with carefully gathered data, can provide process data on how treatment can affect individual responses to stressors or other events. From a social utility perspective, however, having research focus on narrower and narrower slices of behavior in the search for power raises questions about the value of this research to clients and society. For dealing with this dilemma, it will be necessary to build a series of studies linking improvement in specific aspects of short-term outcome to longer term outcome and ultimately benefit to society.
How should the effectiveness of treatment for alcohol problems be evaluated?
Drugs and Alcohol Today, 2007
In times of information overload, researchers have found ways to synthesise a large amount of data from numerous studies bearing on the effectiveness of treatment for alcohol problems. Two of these ways are discussed: formal meta‐analysis and the box‐score ‘mesa grande’. It is concluded that meta‐analysis cannot answer questions regarding which treatments give the best results in the alcohol field. The mesa grande has certain limitations, which are described, but is useful for the formation of treatment policies when a clear summary of the research evidence on treatment effectiveness is needed. By contrast, large multi‐centre randomised controlled trials with enough statistical power to detect small effects of treatment should normally be preferred when a decision has to be made as to which of two or more specified treatments should be implemented in practice. Unfortunately, two multi‐centre trials, one in the USA and one in the UK, have given rise to the ‘dodo bird’ verdict of equi...
2011
The delivery of brief interventions (BIs) in health care settings to reduce problematic alcohol consumption is a key preventive strategy for public health. However, evidence of effectiveness beyond primary care is inconsistent. Patient populations and intervention components are heterogeneous. Also, evidence for successful implementation strategies is limited. In this article, recent literature is reviewed covering BI effectiveness for patient populations and subgroups, and design and implementation of BIs. Support is evident for short-term effectiveness in hospital settings, but long-term effects may be confounded by changes in control groups. Limited evidence suggests effectiveness with young patients not admitted as a consequence of alcohol, dependent patients, and binge drinkers. Influential BI components include high-quality change plans and provider characteristics. Health professionals endorse BI and feel confident in delivering it, but training and support initiatives continue to show no significant effects on uptake, prompting calls for systematic approaches to implementing BI in health care.
Drug and Alcohol Review, 2010
Reductions in control group consumption over time that are possibly related to research design affect the impact of brief alcohol interventions (BAI) in clinical settings. Approach.We conducted a systematic review to identify research design factors that may contribute to control group change, strategies to limit these effects and implications for researchers. Studies with control group n > 30 were selected if they published baseline and outcome consumption data, conducted trials in clinical settings in Anglophone countries and did not censor gender or age. Key Findings. Among 38 studies cited in 20 reviews through October 2009, 16 met criteria (n = 31-370). In 54%, controls received alcohol specific handouts, advice and/or referral. Both the number and depth of assessments were highly variable. The percentage change in consumption ranged from -0.10 to -0.84 (mean -0.32), and effect size from 0.04 to 0.70 (mean 0.37). Published data were insufficient for meta-analysis.
2013
Issues. The aim of this study is to compare studies by their setting in order to identify design differences between studies on brief interventions (BI) for heavy alcohol use conducted in primary care and those in hospital settings. Approach. Potential studies were extracted from 16 reviews and from systematically searching literature up to October 2011.We assessed whether the following factors were statistically significant predictors of study setting: exclusion of very heavy/dependent drinkers; mean age of study sample; gender composition of study samples; sample size; total intervention delivery time; number of sessions; interventionist (physician vs. non-physician); various study design and intervention fidelity aspects; accounting for screening/ assessment reactivity; and control condition utilised. Key Findings. Seventy-six studies (30 in primary care and 46 in hospital settings) met the inclusion criteria.The following factors were statistically significant predictors of study setting: number of sessions {odds ratio [OR] = 0.281 [95% confidence interval (CI) 0.081, 0.979; P = 0.046]}, exclusion of very heavy/ dependent drinkers [OR = 0.052 (95% CI 0.004, 0.716, P = 0.027)] and gender composition of study samples [OR = 1.063 (95% CI 1.005, 1.125; P = 0.033)]. Implications. Researchers developing hospital setting BIs for excessive alcohol consumption should take into account methodological issues that could explain differences in the consistency of findings between hospital setting studies and primary care setting studies where BIs have been more consistently found effective in reducing alcohol use. Conclusion. The observed study design differences between hospital and primary care settings might partly explain the disparity in the consistency of findings on effectiveness of BIs between these settings. [Mdege ND, Watson J. Predictors of study setting (primary care vs. hospital setting) among studies of the effectiveness of brief interventions among heavy alcohol users: A systematic review. Drug Alcohol Rev 2013]
Issues in the definition and measurement of drinking outcomes in alcoholism treatment research
Journal of Studies on Alcohol, Supplement, 1994
This article reviews methodological and conceptual issues regarding the choice of drinking outcome measures in alcoholism treatment research. The following issues are discussed: Should drinking outcomes be conceptualized in terms of an underlying unitary disorder, or should provision be made for independent outcomes that cover a wide variety of dimensions? Which drinking outcomes are typically measured in treatment evaluation studies and how are they operationalized? What are the empirical associations among drinking outcome measures? If multiple outcomes are measured, which should be given primary importance? Over what period of time should treatment outcome be evaluated? What procedures can be used to detect, correct or prevent the response bias associated with verbal report methods? Because outcome measures need to fit the hypotheses and practical needs of a particular study, it is unlikely that complete standardization can be achieved across all studies. Nevertheless, given the importance of drinking outcomes and the need for economy, two primary dependent measures are recommended: (1) proportion of available drinking days abstinent; and (2) intensity of drinking, as defined by the total amount consumed (in ounces absolute alcohol) during the follow-up period divided by the number of actual drinking days. This article also proposes a strategy that may help to guide the selection of outcome measures in future research. (J. Stud. Alcohol, Supplement No. 12:101-111, 1994) N A 1988 EDITORIAL, Arnold Relman stated, "We can no longer afford to provide health care without knowing more about its successes and faiIures." Applying this admonition to the treatment of alcoholism, the Institute of Medicine (1990, p. 326) recommended that "consensus must be achieved on the need for outcome determination, on the parameters to be used in determining outcome, and on the optimal way(s) to go about making outcome determinations." The goal of this article is to review methodological and conceptual issues regarding the choice of alcohol-related outcome measures in alcoholism treatment research. Alcoholrelated outcomes are the measures of drinking behavior, alcohol dependence symptoms and alcohol-related consequences that are directly attributable to drinking following treatment. A secondary goal of this article is to suggest ways that greater standardization could be introduced to the planning, execution and reporting of treatment research. Because