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Background: Internet-based interventions are seen as attractive for harmful users of alcohol and lead to desirable clinical outcomes. Some participants will however not achieve the desired results. In this study, harmful users of alcohol have been partitioned in subgroups with low, intermediate or high probability of positive treatment outcome, using recursive partitioning classification tree analysis. Methods: Data were obtained from a randomized controlled trial assessing the effectiveness of two Internet-based alcohol interventions. The main outcome variable was treatment response, a dichotomous outcome measure for treatment success. Candidate predictors for the classification analysis were first selected using univariate regression. Next, a tree decision model to classify participants in categories with a low, medium and high probability of treatment response was constructed using recursive partitioning software. Results: Based on literature review, 46 potentially relevant baseline predictors were identified. Five variables were selected using univariate regression as candidate predictors for the classification analysis. Two variables were found most relevant for classification and selected for the decision tree model: 'living alone', and 'interpersonal sensitivity'. Using sensitivity analysis, the robustness of the decision tree model was supported. Conclusions: Harmful alcohol users in a shared living situation, with high interpersonal sensitivity, have a significantly higher probability of positive treatment outcome. The resulting decision tree model may be used as part of a decision support system but is on its own insufficient as a screening algorithm with satisfactory clinical utility. [ABSTRACT FROM AUTHOR]

Background: Only a minority of all alcohol- and drug abusers is receiving professional care. In an attempt to narrow this treatment gap, treatment facilities experiment with online healthcare. Therefore, it is important to test the (cost-)effectiveness of online health interventions in a randomized clinical trial. Methods: This paper presents the protocol of a three-arm randomized clinical trial to test the (cost-) effectiveness of online treatment for problem drinkers. Self-help online, therapy online and a waiting list are tested against each other. Primary outcome is change in alcohol consumption. Secondary outcome measures include quality of life and working ability. Incremental cost-effectiveness ratios for self-help online alcohol and therapy online alcohol will be calculated. The predictive validity of participant characteristics on treatment adherence and outcome will be explored. Discussion: To our best knowledge, this randomized clinical trial will be the first to test the effectiveness of therapy online against both self-help online and a waiting-list. It will provide evidence on (cost-) effectiveness of online treatment for problem drinkers and investigate outcome predictors. Trial registration: This trial is registered in the Dutch Trialregister (Cochrane Collaboration) and traceable as NTR-TC1155. [ABSTRACT FROM AUTHOR]