Efficacy of an Online, Group-Based Internal Family Systems (IFS) Intervention on PTSD Symptom Clusters

Abstract

Background and Objectives - Posttraumatic stress disorder (PTSD) is a debilitating condition that often follows exposure to traumatic experiences. Its symptoms are defined in the Diagnostic & Statistics Manual, 5th edition, text revision (DSM-5-TR; American Psychiatric Association, 2022) and organized by specific criteria (intrusion Criterion B, avoidance Criterion C, negative cognition Criterion D, hyperarousal Criterion E). Current treatments show promise in alleviating PTSD symptoms but rarely fit all patients. There is, therefore, a need for continued development of new modalities. Internal Family Systems (IFS) is an innovative intervention that has gained popularity since its inception forty years ago. Preliminary studies have shown its potential in alleviating symptoms of traumatic stress, yet, evidence of its efficacy remains to be established. This individual participant data (IPD) meta-analysis aims to scrutinize the efficacy of an online, group based IFS intervention on PTSD symptom clusters. It postulates that overall PTSD symptoms will improve, with greatest reductions seen in intrusion (Criterion B) and avoidance (Criterion C) symptoms. Methods - Four studies (N = 76 participants) were included in this IPD meta-analysis. All involved an online, group-based IFS intervention for PTSD paired with individual IFS therapy sessions. Pre-/post-intervention PTSD CheckList for DSM-5 (PCL-5; Blevins et al., 2015) data were collected via self-reported surveys. The primary aim of this work is to assess the efficacy of the IFS intervention by cluster of PTSD symptoms as defined by the DSM-5-TR. A two-stage individual participant data (IPD) meta-analysis with random effects, measuring differences in effect sizes followed by meta-regressions with and without moderating variables were performed. Results - The meta-analysis by cluster showed large negative effect sizes for all symptom clusters (gB= -1.17, gD= -1.12, gC= -1.04, gE= -0.80, p.05, pHB 0.05), yet with low certainty around the estimates (wide 95% CIs). Heterogeneity statistics did not reveal any between-study variability, indicative of consistent study protocols and intervention designs. While intrusion (Criterion B) and negative cognition (Criterion D) appeared to have markedly higher effect sizes, a meta-regression using clusters as a moderator, disproved the significance of the effect size differences (p>0.05, pHB > 0.05). Hence, clusters do not contribute differently to the reduction in PTSD symptoms. Discussion and Conclusions - Overall, the IFS intervention showed significant efficacy in reducing overall PTSD severity. Even though efficacy was not linear across PTSD clusters, and intrusion (Criterion B) and negative cognition (Criterion D) in particular showed observable reduction in gravity, no cluster significantly differed in terms of effect sizes. These results indicate that IFS improves symptoms of PTSD homogeneously across symptom clusters. This aligns with empirical findings from the existing literature regarding other PTSD treatment modalities (including CBT and EMDR), which show a lack of differentiation in efficacy amongst PTSD symptom clusters. All in all, this IPD meta-analysis adds to the emerging research showing the efficacy of IFS as a modality of psychotherapy to alleviate PTSD. It is encouraging as novel types of therapy are needed to complement existing interventions and support patients who do not benefit from them. Scientific Significance - An innovative modality of psychotherapy, IFS could effectively alleviate symptoms of PTSD. The results of this IPD meta-analysis carry important implications for people suffering from PTSD. Adding a novel, evidence-based option for therapy that has the potential to holistically improve PTSD symptoms is encouraging for the many people who do not find relief with other existing modalities of treatment.