In routine care, internet-delivered cognitive behaviour therapy (iCBT) regularly includes therapist support delivered via secure email, but the optimal response time to emails is unknown. In this study, we compared the benefits of therapists providing support once-weekly versus therapists providing support once-weekly supplemented with a one-business-day response to all patient emails. This pragmatic randomized controlled trial included therapists employed by a specialized iCBT clinic or community mental health clinics, where providing iCBT is a secondary service. Patients with depression and/or anxiety who enrolled in transdiagnostic iCBT (5 core lessons over 8 weeks) were randomized to: 1) once-weekly support supplemented with a one-business-day response to patient emails by specialized therapists (n = 233); 2) once-weekly support also offered by specialized therapists (n = 216); or 3) once-weekly support offered by community clinic therapists (n = 226). Outcomes were measured at 8, 12, 24, and 52-weeks post-enrollment. Patient engagement and treatment experiences (e.g., treatment satisfaction, therapist alliance) were also assessed and a focus group was conducted with therapists. Supplementing once-weekly therapist support with a one-business-day response to patient emails resulted in therapists sending more emails to patients (M: 13 versus 9) and required more therapist time over treatment (M: 155 versus 109 min), but was not associated with improved outcomes, patient engagement or treatment experiences. All groups showed large improvements in symptoms of depression and anxiety maintained at 52-week follow-up, strong engagement and positive treatment experiences. Therapists viewed challenges of responding to patient emails within one-business-day to outweigh benefits. Contrary to expectations, supplementing once-weekly therapist support with a one-business-day response to all patient emails did not benefit patients and increased therapist time as well as therapist challenges when delivering iCBT in routine care.

在常规护理中，互联网提供的认知行为疗法（iCBT）通常包括通过安全电子邮件提供的治疗师支持，但电子邮件的最佳响应时间尚不清楚。在这项研究中，我们比较了治疗师每周提供一次支持与治疗师每周提供一次支持并辅以一个工作日回复所有患者电子邮件的好处。这项务实的随机对照试验包括由专门的 iCBT 诊所或社区心理健康诊所雇用的治疗师，其中提供 iCBT 是次要服务。参加跨诊断 iCBT（8 周内 5 门核心课程）的抑郁和/或焦虑患者被随机分配到：1) 每周一次的支持，辅以专业治疗师对患者电子邮件的一个工作日回复 ( n = 233) ; 2) 每周一次的支持也由专业治疗师提供（ n = 216）；或 3) 由社区诊所治疗师提供每周一次的支持 ( n = 226)。结果在入组后 8、12、24 和 52 周进行测量。还评估了患者参与度和治疗体验（例如治疗满意度、治疗师联盟），并与治疗师进行了焦点小组讨论。通过对患者电子邮件进行一个工作日回复来补充每周一次的治疗师支持，导致治疗师向患者发送更多电子邮件（ M ：13 分钟与 9 分钟），并且需要更多的治疗师治疗时间（ M ：155 分钟与 109 分钟），但与改善结果、患者参与或治疗体验无关。在 52 周的随访中，所有组的抑郁和焦虑症状均表现出大幅改善，并具有强烈​​的参与度和积极的治疗体验。 治疗师认为在一个工作日内回复患者电子邮件的挑战超过了好处。与预期相反，通过对所有患者电子邮件进行一个工作日回复来补充每周一次的治疗师支持并没有给患者带来好处，并且增加了治疗师的时间以及在常规护理中提供 iCBT 时治疗师面临的挑战。