Internet-delivered acceptance and commitment therapy as microlearning for chronic pain: A randomized controlled trial with 1-year follow-up

Background: Studies of Internet-delivered acceptance and commitment therapy (ACT) for chronic pain have shown small to moderate positive effects for pain interference and pain acceptance. Effects on pain intensity, depression, anxiety and quality of life (QoL) have been less favourable, and improvements for values and sleep are lacking. In this randomized controlled trial iACT - a novel format of Internet-ACT using daily microlearning exercises - was examined for efficacy compared to a waitlist condition. Methods: Adult participants (mean age 49.5 years, pain duration 18.1 years) with diverse chronic pain conditions were recruited via self-referral, and randomized to iACT (n = 57) or waitlist (n = 56). The primary outcome was pain interference. The secondary outcomes were QoL, depression, anxiety, insomnia and pain intensity. The process variables included psychological inflexibility and values. Post-assessments were completed by 88% (n = 100) of participants. Twelve-month follow-up assessments were completed by 65% (iACT only, n = 37). Treatment efficacy was analysed using linear mixed models and an intention-to-treat-approach. Results: Significant improvements in favour of iACT were seen for pain interference, depression, anxiety, pain intensity and insomnia, as well as process variables psychological inflexibility and values. Between-group effect sizes were large for pain interference (d = 0.99) and pain intensity (d = 1.2), moderate for anxiety and depressive symptoms and small for QoL and insomnia. For the process variables, the between-group effect size was large for psychological inflexibility (d = 1.0) and moderate for values. All improvements were maintained at 1-year follow-up. Conclusions: Internet-ACT as microlearning may improve a broad range of outcomes in chronic pain. Significance: The study evaluates a novel behavioral treatment with positive results on pain interference, mood as well as pain intensity for longtime chronic pain sufferers. The innovative format of a digital ACT intervention delivered in short and experiential daily learnings may be a promising way forward.