Investigating the Influence of Self-Compassion-Focused Interventions on Posttraumatic Stress: A Systematic Review and Meta-Analysis

Objectives Self-compassion-focused interventions may be able to decrease posttraumatic stress symptoms. However, previous studies demonstrated mixed effects in which a series of confounders were not systematically quantified. In this study, a systematic review with meta-analysis was conducted to quantify the effects of self-compassion-focused therapies on posttraumatic stress disorder. Methods Twelve eligible studies were included after a systematic search of databases. Outcome measures were extracted for posttraumatic stress disorder. Results Our data indicated a medium protective effect on posttraumatic stress symptoms (SMD = -0.65), with most of the studies (8/12) coming from clinical settings. More importantly, longer interventions were associated with better posttraumatic stress outcomes (p < 0.001). Baseline or changes in self-compassion scores were not associated with posttraumatic stress outcomes post-interventions. Conclusions Overall, findings from this meta-analysis quantified the complex influence of self-compassion-focused interventions on posttraumatic stress symptoms and may provide insights for optimizing intervention strategies.

Recent studies highlight the potential of self-compassionfocused interventions in the management of posttraumatic stress disorder (PTSD) (Serpa et al., 2021; Winders et al., 2020) , which occurs following exposure to severe accidents, for example, actual or threatened death, domestic violence, war, or natural disaster (American Psychiatric Association, 2013) . However, studies have demonstrated mixed effects and it is important to optimize the benefits of self-compassion-focused interventions on PTSD. Distinct effects may be associated with variances in self-compassion protocols. Randomized controlled designs are critical to interventions and it is noted that studies varied in terms of the presence of a control group. Study participants have varied, which included clinical (i.e., individuals with a previous diagnosis) or nonclinical samples (i.e., the general populations without a clinical diagnosis, such as postpartum mothers and college students) (Hwang & Chan, 2019; Mitchell et al., 2018) . A recent study supported the efficacy of self-compassion interventions across diverse populations (Ferrari et al., 2019) . Moreover, the literature varied in the number of sessions from four to twelve (Au et al., 2017; Evans et al., 2019; Grodin et al., 2019; Held & Owens, 2015) . Studies have demonstrated that the efficacy of self-compassion-focused therapies is shaped by the number of training session (Phillips & Hine, 2019; Wakelin et al., 2021) . Other factors may as well play a role in intervention outcomes, such as the way of delivering interventions (e.g., group-based class or self-administration). It is therefore important to characterize and quantify these confounders in a systematic fashion with meta-analysis.

The current meta-analytic study was designed to explore the complex effects of self-compassion-focused approaches on PTSD symptoms. Potential confounders were, therefore, carefully examined in this context. We also assessed the changes in self-compassion score which is supposed to be closely associated with intervention outcomes (Bistricky et al., 2017; Valdez & Lilly, 2016; Zeller et al., 2015) . Overall, findings from this meta-analysis may help to quantify the complex influence of self-compassion-focused interventions on PTSD symptoms and therefore provide insights for optimizing intervention strategies.