Department of Psychiatry, Oxford University, Oxford, UK.
Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK.
Int J Eat Disord. 2020 Dec;53(12):1928-1940. doi: 10.1002/eat.23390. Epub 2020 Nov 5.
Understanding the mechanisms of action of psychological treatments is a key first step in refining and developing more effective treatments. The present study examined hypothesized mediators of change of enhanced cognitive behavior therapy (CBT-E) and interpersonal psychotherapy for eating disorders (IPT-ED).
A series of mediation studies were embedded in a randomized controlled trial (RCT) comparing 20 weeks of CBT-E and IPT-ED in a transdiagnostic, non-underweight sample of patients with eating disorders (N = 130) consecutively referred to the service. Three hypothesized mediators of change in CBT-E (regular eating, weighing frequency, and shape checking) and the key hypothesized mediator of IPT-ED (interpersonal problem severity) were studied.
The data supported regular eating as being a mediator of the effect of CBT-E on binge-eating frequency. The findings were inconclusive regarding the role of the other putative mediators of the effects of CBT-E; and were similarly inconclusive for interpersonal problem severity as a mediator of the effect of IPT-ED.
This research highlights the potential benefits of embedding mediation studies within RCTs to better understand how treatments work. The findings supported the role of regular eating in reducing patients' binge-eating frequency. Other key hypothesized mediators of CBT-E and IPT-ED were not supported, although the data were not inconsistent with them. Key methodological issues to address in future work include the need to capture both behavioral and cognitive processes of change in CBT-E, and identifying key time points for change in IPT-ED.
理解心理治疗作用机制是完善和发展更有效的治疗方法的关键第一步。本研究检验了增强认知行为治疗（CBT-E）和进食障碍人际心理治疗（IPT-ED）的假设变化中介。
在一项针对连续转介到服务的进食障碍（N=130）非体重不足患者的跨诊断样本中，将 20 周的 CBT-E 和 IPT-ED 进行随机对照试验（RCT），并嵌入了一系列中介研究。研究了 CBT-E 中的三个假设变化中介（规律进食、称重频率和体形检查）和 IPT-ED 的关键假设变化中介（人际问题严重程度）。
数据支持规律进食是 CBT-E 对暴食频率影响的中介。关于 CBT-E 效果的其他假设中介的作用的研究结果并不明确；IPT-ED 效果的人际问题严重程度作为中介的作用的研究结果也同样不明确。
本研究强调了在 RCT 中嵌入中介研究以更好地理解治疗方法如何发挥作用的潜在益处。研究结果支持了规律进食在减少患者暴食频率方面的作用。其他关键假设的 CBT-E 和 IPT-ED 中介因素没有得到支持，尽管数据与它们并不矛盾。未来工作中需要解决的关键方法学问题包括需要在 CBT-E 中捕捉行为和认知变化过程，以及确定 IPT-ED 中变化的关键时间点。
