Time to take the Declaration of Helsinki seriously? A systematic review of comparison conditions in clinical trials on internet-delivered cognitive behavioral therapy for insomnia

The Declaration of Helsinki (DoH) provides guidance on the choice of comparators in clinical trials, stating that new treatments must be compared against the best proven treatment. This systematic review examines whether research on a new treatment – internet-delivered cognitive behavioral therapy for insomnia (iCBT-I) – has adhered to these DoH requirements. A systematic literature search for randomized controlled trials (RCTs) testing iCBT-I in clinical samples was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. To identify the gold standard treatment, national guidelines were analyzed for all countries where published research on iCBT-I had been conducted.
After screening, 32 RCTs and seven guidelines for 12 countries were included. Almost all guidelines recommend face-to-face CBT-I as the gold standard, but only four (12.5 %) of the RCTs used this gold standard as a comparator. None of the other trials explained why they did not follow the DoH's recommendation.
The majority of clinical trials did not compare iCBT-I against the gold standard. As the DoH is intended to guide clinical research ethics, this low level of adherence is remarkable, and it raises uncertainty for patients, therapists, and policymakers about the effectiveness of iCBT-I compared to the gold standard treatment.