Group-blended and individual-unguided online mindfulness-based cognitive therapy for people with cancer: long-term effects, moderation, and prediction of a randomized controlled trial.

This dataset comes from the follow-up data of a three-arm randomized controlled trial (RCT) evaluating two formats of online mindfulness-based cognitive therapy (eMBCT) for individuals with cancer. The collection contains the raw trial data, the analysis syntax, and the results from the long-term effects, prediction, and moderation analyses. A README file is also included to help readers navigate the materials and understand the contents of the collection. ABSTRACT: Background: A three-arm RCT showed that two online mindfulness-based cognitive therapy formats (eMBCT)—group-blended and individual-unguided—reduced psychological distress and improved health outcomes in people with cancer, compared to care as usual, up to three months post-treatment. Long-term effects and predictors remain unclear. Objective: To examine long-term effects (up to nine months) of group-blended and individual-unguided eMBCT on psychological distress and mental health outcomes, and explore predictors and moderators of treatment effects. Methods: Participants with cancer were randomized to group-blended or individual-unguided eMBCT (N = 161; 71 group-blended, 90 individual-unguided), including those reallocated from a waitlist. Assessments at baseline, post-treatment, and 3-, 6-, and 9-month follow-ups measured psychological distress (primary), fear of recurrence, rumination, fatigue, mindfulness skills, decentering, self-compassion, and well-being. Linear mixed-effects models and logistic regression tested changes, predictors, and moderators. Results: Participants were mainly female (80%), with breast cancer (48%), mean age 52.8. Both formats significantly reduced distress, fear of recurrence, rumination, and fatigue, while improving mindfulness, decentering, and self-compassion up to nine months. Greater baseline rumination, and lower mindfulness and self-compassion predicted larger distress reductions. Highly distressed participants were more likely to drop out of group-blended eMBCT, but not individual-unguided. No other moderators were found. Conclusions: Both eMBCT formats reduced distress and improved well-being, with greater benefits for those with fewer psychological resources. However, highly distressed individuals were more likely to discontinue group-blended therapy. Treatment choice should consider personal preferences and practical factors in shared decision-making.