The number of acceptance- and mindfulness-based interventions for chronic pain, such as acceptance and commitment therapy (ACT), mindfulness-based stress reduction (MBSR), and mindfulness-based cognitive therapy (MBCT), increased in recent years. Therefore an update is warranted of our former systematic review and meta-analysis of studies that reported effects on the mental and physical health of chronic pain patients. Pubmed, EMBASE, PsycInfo and Cochrane were searched for eligible studies. Current meta-analysis only included randomized controlled trials (RCTs). Studies were rated for quality. Mean quality did not improve in recent years. Pooled standardized mean differences using the random-effect model were calculated to represent the average intervention effect and, to perform subgroup analyses. Outcome measures were pain intensity, depression, anxiety, pain interference, disability and quality of life. Included were twenty-five RCTs totaling 1285 patients with chronic pain, in which we compared acceptance- and mindfulness-based interventions to the waitlist, (medical) treatment-as-usual, and education or support control groups. Effect sizes ranged from small (on all outcome measures except anxiety and pain interference) to moderate (on anxiety and pain interference) at post-treatment and from small (on pain intensity and disability) to large (on pain interference) at follow-up. ACT showed significantly higher effects on depression and anxiety than MBSR and MBCT. Studies' quality, attrition rate, type of pain and control group, did not moderate the effects of acceptance- and mindfulness-based interventions. Current acceptance- and mindfulness-based interventions, while not superior to traditional cognitive behavioral treatments, can be good alternatives.
Keywords: Mindfulness; acceptance; acceptance and commitment therapy; chronic pain; meta-analysis.