Supplementary Material for: Internet-Delivered Disease Management for Recurrent Depression: A Multicenter Randomized Controlled Trial

Background: Strategies to improve the life of patients suffering from recurrent major depression have a high relevance. This study examined the efficacy of 2 Internet-delivered augmentation strategies that aim to prolong symptom-free intervals. Methods: Efficacy was tested in a 3-arm, multicenter, open-label, evaluator-blind, randomized controlled trial. Upon discharge from inpatient mental health care, 232 adults with 3 or more major depressive episodes were randomized to 1 of 2 intervention groups (SUMMIT or SUMMIT-PERSON) or to treatment as usual (TAU) alone. Over 12 months, participants in both intervention arms received, in addition to TAU, intense monitoring via e-mail or a smartphone, including signaling of upcoming crises, assistance with personal crisis management, and facilitation of early intervention. SUMMIT-PERSON additionally offered regular expert chats. The primary outcome was ‘well weeks', i.e. weeks with at most mild symptoms assessed by the Longitudinal Interval Follow-Up Evaluation, during 24 months after the index treatment. Results: SUMMIT compared to TAU reduced the time with an unwell status (OR 0.48; 95% CI 0.23-0.98) through faster transitions from unwell to well (OR 1.44; 95% CI 0.83-2.50) and slower transitions from well to unwell (OR 0.69; 95% CI 0.44-1.09). Contrary to the hypothesis, SUMMIT-PERSON was not superior to either SUMMIT (OR 0.77; 95% CI 0.38-1.56) or TAU (OR 0.62; 95% CI 0.31-1.24). The efficacy of SUMMIT was strongest 8 months after the intervention. Conclusions: The fully automated Internet-delivered augmentation strategy SUMMIT has the potential to improve TAU by reducing the lifelong burden of patients with recurrent depression. The fact that the effects wear off suggests a time-unlimited extension.