Internet-delivered psychological treatment as an add-on to treatment as usual for common mental disorders : A systematic review with meta-analysis of randomized trials

Background: Psychological treatments for common mental disorders are increasingly being delivered remotely via the internet. Evidence suggests that internet-delivered cognitive behavioural therapy (iCBT) is superior to waitlist. However, the benefits are unclear of using this treatment modality as an add-on to treatment as usual (TAU) in regular healthcare. Methods: The literature was systematically searched up to August 2021 for randomized trials of internet-delivered psychological treatments using TAU as the comparator. Eligible participants were diagnosed with depressive, anxiety, obsessive-compulsive, or trauma- and stress-related disorders. Outcomes of interest were symptoms, functioning, quality of life, healthcare utilization, and negative effects. Results were synthesized using random-effects meta-analyses. Quality of evidence was assessed using GRADE. Results: The included studies evaluated iCBT for adults with depression (k = 9), depressive or anxiety disorders (k = 4), and post-traumatic stress disorder (k = 2) and were conducted in primary care or similar settings. For depression, low-certainty evidence suggested beneficial short-term effects on symptoms (g = −0.23; 95 % CI: = −0.37, −0.09), response rate (OR = 2.46; 1.31, 4.64), and remission (OR = 1.70; 1.19, 2.42;). The certainty of evidence was very low for long-term effects, other outcomes, and other disorders. Limitations: TAU varied across studies and was often insufficiently described. Conclusions: iCBT as a complement to usual care for adult with depression may result in a small incremental effect, which potentially could be clinically important. Studies are lacking for several common disorders and for children, adolescents, and the elderly. More robust studies of long-term effects are also needed, to better inform clinical decision-making