Predicting patient post-detoxification engagement in 12-step groups with an extended version of the theory of planned behavior

INTRODUCTION: Individuals with substance use disorders can receive important abstinence-specific support in 12-step groups (TSGs). However, our understanding of key factors that influence TSG participation remains limited. This study used an extended version of the theory of planned behavior (TPB) to enhance the understanding of TSG affiliation. METHODS: Data were retrieved from a controlled trial of a 12-step facilitation intervention conducted on an inpatient detoxification ward in Norway (N = 140). Surveys at baseline included a TPB questionnaire. The behavioral target was to attend at least two TSG meetings per month in the 6-month follow-up period. Structural equation modeling was used to analyze the predictors of behavior at follow-up. RESULTS: We found that attitudes, the moral norm, and perceived behavior control accounted for 81 % of the variance in the intention to participate regularly in TSGs after treatment. Subjective norms did not significantly influence the intention to participate. Moreover, the intention to participate significantly predicted behavior (β = 0.42, p < 0.001). In contrast to theory, there was a substantial, model-independent pathway from past to later behavior (β = 0.22, p = 0.047). The model explained 46 % (p < 0.001) of the variance in behavior. Attending ≥ 12 TSG meetings in the follow-up period was associated with a high percentage of abstinent days at follow-up (β = 0.38, p = 0.023). CONCLUSIONS: The present TPB questionnaire worked well for assessing patient intentions to attend a TSG. Treatment providers should encourage patient intentions to participate in TSGs post-detoxification. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13722-015-0036-3) contains supplementary material, which is available to authorized users.