Discussion
depressive, depression, anxiety, CBT-SH
ADVERSE EVENTS, SECONDARY, BLIND
The primary hypothesis was supported: practitioner-supported MBCT-SH was superior to practitioner-supported CBT-SH in reducing depressive symptom severity at postintervention follow-up. In addition, PWP-supported MBCT-SH was found to be cost-effective compared with PWP-supported CBT-SH due to significantly lower total costs alongside similar QALY outcomes.No serious adverse events attributable to the interventions were reported, and lasting negative effects were uncommon and similar in each arm, in line with previous psychological intervention research.This study found that practitioner-supported MBCT-SH is not only more clinically effective than CBT-SH but also more cost-effective. On average, the CBT-SH intervention cost health services £526 ($631) more per participant than the MBCT-SH intervention over the 42-week follow-up. A substantial proportion of this additional cost (approximately 50%) was accounted for by additional face-to-face individual psychological therapy accessed by CBT-SH participants outside of the study intervention. If practitioner-supported MBCT-SH were offered as an alternative, it might be expected that some of the cost savings would fall on health services, potentially supporting increased treatment capacity.Findings corroborate and extend findings from previous RCTs of MBCT-SH.In relation to secondary outcomes, we also found superior effects of supported MBCT-SH over CBT-SH on anxiety symptom severity at postintervention. At 42-week follow-up, between-group effects on depressive and anxiety symptom severity remained in the hypothesized direction but were nonsignificant. This could in part by explained by the greater postintervention psychological therapy accessed by CBT-SH participants. Lack of effects at postintervention and follow-up on all but the nonjudge mindfulness subscale was not expected. This potentially suggests that MBCT-SH relative to CBT-SH is effective at improving the specific mindfulness capacity to be accepting of unpleasant thoughts and emotions but not other aspects of the mindfulness construct. Existing measures of mindfulness may need reevaluating to improve their ability to discriminate the specific effects of MBCT.This trial recruited across multiple services representing a broad range of geographic, rural and urban, and sociodemographic characteristics, suggesting that findings can be generalized to other psychological therapy services. The research team included researchers from a predominantly CBT background, an MBCT background, and from both traditions, reducing allegiance effects. Assessments were conducted blind to treatment allocation, participants were not informed about the hypothesized direction of effects, and data analysis was conducted with treatment arm masked, all reducing risk of bias. This pragmatic trial was conducted in the real-world public mental health setting, training practitioners within services to deliver MBCT-SH. This points to feasibility of implementation of practitioner-supported MBCT-SH for depression.Our findings suggest that offering practitioner-supported MBCT-SH as an intervention for mild to moderate depression would improve outcomes and save money compared with practitioner-supported CBT-SH. Therefore, practitioner-supported MBCT-SH should be routinely offered as an intervention for mild to moderate depression alongside practitioner-supported CBT-SH. This would increase patient choice, as currently only CBT-SH is typically recommended in treatment guidelines for depression.Future research should aim to corroborate and extend findings, for example by including more frequent assessments to allow trajectory and mechanisms of change to be more fully explored. Implementing research findings in routine clinical practice is notoriously challenging. Future research should examine factors enabling successful implementation of practitioner-supported MBCT-SH to expedite the pathway to patient benefit and to ensure fidelity to the approach. Future research should include evaluating the relative effectiveness and acceptability of different formats of MBCT-SH for depression, including book-based (as in the current study) and online