Changes in Acceptance in a Low-Intensity, Group-Based Acceptance and Commitment Therapy (ACT) Chronic Pain Intervention

Acceptance and commitment therapy has shown to be effective in chronic pain rehabilitation, and acceptance has been shown to be a key process of change. The influence of treatment dose on acceptance is not clear, and in particular, the effectiveness of a non-intensive treatment (< 20 h) in a tertiary pain clinic is required. The purpose of the study was to assess the effectiveness of a low-intensity, acceptance and commitment therapy (ACT) group program for chronic pain. The study sought to compare, at both groups and individual patient levels, changes in acceptance with changes observed in previous ACT studies. Seventy-one individuals with chronic pain commenced a 9-week ACT-based group program at an outpatient chronic pain service. In addition to acceptance, outcomes included the following: pain catastrophizing, depression, anxiety, quality of life, and pain-related anxiety. To compare the current findings with previous research, effect sizes from seven studies were aggregated using the random-effects model to calculate benchmarks. Reliable change indices (RCIs) were applied to assess change on an individual patient-level. The ACT intervention achieved a statistically significant increase in acceptance and medium effect size (d = 0.54) at a group level. Change in acceptance was of a similar magnitude to that found in previous ACT studies that examined interventions with similar treatment hours (< 20 h). Results across other outcome measures demonstrated small to medium effect sizes (d = 0.01 to 0.48, mean = 0.26). Reliable improvement in acceptance occurred in approximately one-third (37.2, 90 % CI) of patients. Approximately three-quarters (74.3, 90 % CI) demonstrated reliable change in at least one of the outcome measures. The low-intensity, group-based ACT intervention was effective at a group level and showed a similar magnitude of change in acceptance to previous ACT studies employing low-intensity interventions. Three-quarters of patients reported reliable change on at least one outcome measure.