OBJECTIVE A randomized trial informed by the Health Action Process Approach evaluated interventions to improve cardiac rehabilitation completion following myocardial infarction. We investigated indirect effects of the interventions on completion via targeted constructs. METHODS In this theory-based process evaluation, participants in all 3 trial arms (usual care; mailouts; mailouts plus telephone support) completed a questionnaire 12 months after their myocardial infarction assessing intention, goal priority, outcome expectancies, risk perception, self-efficacy, social support, action planning, and coping planning. Consecutive sampling was used until the target sample size (167 per trial arm) was met. Cardiac rehabilitation completion was self-reported at the same time point. We used multiple regression mediation models to explore indirect effects. RESULTS In total, 594 participants completed the cardiac rehabilitation questionnaire; 588 were analyzed (6 excluded due to missing data). For mailouts alone, there were no significant indirect effects. There were small indirect effects of mailouts plus telephone support on intention via goal priority, outcome expectancies, and self-efficacy, with a negative effect via severity risk perception. There were also small indirect effects on cardiac rehabilitation completion via self-efficacy and action planning. CONCLUSIONS Findings help explain the trial results, suggesting that mailouts plus telephone support increased the likelihood of completing cardiac rehabilitation by enhancing self-efficacy and action planning, and increased intention by enhancing goal priority, self-efficacy, and outcome expectancies, with an unintended consequence of a negative effect via risk perceptions. Conducting theory-based process evaluations alongside trials of behavior change interventions can clarify mechanisms of action, which can inform efforts to refine interventions and to replicate and generalize findings to other jurisdictions. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

中文翻译：

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支持心脏康复完成的干预措施：过程评估研究基于理论的作用机制。

目的根据健康行动过程方法进行的一项随机试验，评估了干预措施以改善心肌梗死后心脏康复的完成情况。我们通过有针对性的结构调查了干预措施对完成工作的间接影响。方法在此基于理论的过程评估中，所有3个试验部门（常规护理，邮寄，邮寄加上电话支持）的参与者在心肌梗死评估目的，目标优先级，结果预期，风险感知，自我效能评估12个月后完成问卷，社会支持，行动计划和应对计划。连续取样直至达到目标样本量（每个试验组167个）。在同一时间点自我报告心脏康复的完成情况。我们使用了多种回归中介模型来探索间接影响。结果共有594名参与者完成了心脏康复问卷；分析了588个（由于缺少数据，排除了6个）。仅就邮寄而言，没有明显的间接影响。通过目标优先级，结果预期和自我效能感，邮寄和电话支持对意图的间接影响较小，而通过严重度风险感知则产生负面影响。通过自我效能感和行动计划，对心脏康复的完成也有较小的间接影响。结论研究结果有助于解释试验结果，表明邮寄和电话支持可通过提高自我效能和行动计划来增加完成心脏康复的可能性，并通过提高目标优先级，自我效能和结果预期来增加意图，通过风险感知产生负面影响的意想不到的结果。与行为改变干预措施的试验一起进行基于理论的过程评估可以阐明行动机制，这可以为改进干预措施以及向其他辖区复制和推广调查结果提供参考。（PsycInfo数据库记录（c）2020 APA，保留所有权利）。