Background
Treatment involvement, including involvement with written material as well as homework assignments, has previously been associated with better outcomes in cognitive behavioral therapy, but there is a lack of knowledge on which specific aspects of involvement that are the most promising for use as predictors of treatment effects.
Methods
The objective of this study was to use a battery of weekly self-rated questions regarding different aspects of participant involvement during 8 weeks of either guided internet cognitive behavioral therapy for insomnia (ICBT-i, n = 73), or an active internet-delivered control treatment also including homework (ICBT-ctrl, n = 75), to predict reductions in insomnia severity after treatment. The markers of involvement were single questions on amount of time spent on treatment, amount of text read, amount of subjective knowledge gained and index scores of homework quantity (based on ratings of how many times specific techniques were used) and homework quality (based on ratings of the understanding, used as intended, and helpfulness of each specific technique).
Results
While none of the markers predicted reductions in insomnia severity for participants in the ICBT-ctrl group, text read, subjective knowledge gain, and homework quality predicted larger reductions in insomnia severity for participants in ICBT-i. Amount of subjective knowledge gained was a particularly useful marker in the ICBT-i group, since weekly ratings from the first half of treatment sufficed to explain a rather large proportion of variance in insomnia severity post treatment (14%).
Conclusions
The results strengthen subjective knowledge gain as a candidate for use as a predictor of treatment effects in ICBT-i.