A meta-analysis of dropout rates in acceptance and commitment therapy

Many psychotherapies, including cognitive behavioral therapy and acceptance and commitment therapy (ACT), have been found to be effective interventions for a range of psychological and behavioral health concerns. Another aspect of treatment utility to consider is dropout, as interventions only work if clients are engaged in them. To date, no research has used meta-analytic methods to examine dropout in ACT. Thus, the objectives of the present meta-analysis were to (1) determine the aggregate dropout rate for ACT in randomized controlled trials, (2) compare dropout rates in ACT to those in other psychotherapies, and (3) identify potential moderators of dropout in ACT. Our literature search yielded 68 studies, representing 4,729 participants. The weighted mean dropout rates in ACT exclusive conditions and ACT inclusive conditions (i.e., those that included an ACT intervention) were 15.8% (95% CI: 11.9%, 20.1%) and 16.0% (95% CI: 12.5%, 19.8%), respectively. ACT dropout rates were not significantly different from those of established psychological treatments. In addition, dropout rates did not vary by client characteristics or study methodological quality. However, master's-level clinicians/therapists (weighted mean = 29.9%, CI: 17.6%, 43.8%) were associated with higher dropout than psychologists (weighted mean = 12.4%, 95% CI: 6.7%, 19.4%). More research on manipulable, process variables that influence dropout is needed.