1. Across 56 randomized controlled trials with 4,060 participants, psychosocial interventions were significantly associated with improved immune system function.
2. Immune system improvements persisted for at least six months post-treatment.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Inflammation-related diseases account for a large portion of global mortality. Many RCTs have focused on specific psychosocial interventions and their effects on the immune system. In the event that non-pharmacological intervention can improve immune system functionality, this could serve as an adjunctive or possibly primary initial treatment for those with inflammation.
This study aimed to assess these RCTs across immune system measures as well as factors related to psychosocial interventions. Each RCT included a randomized psychosocial intervention for the purpose of assessing immune function both at baseline and at treatment conclusion. The overall effect size suggested that psychosocial interventions, broadly speaking, resulted in significantly improved immune system function as measured by seven immune system outcomes. Psychosocial intervention was investigated based on several moderating factors: type, format, type of immune marker, duration, time from treatment discontinuation to immune marker measurements, participant disease state, age, sex, and type of immune marker. The immune system plays a critical role in mental and physical health, such that psychosocial interventions may be the treatment of choice if medication is deemed unnecessary or insufficient. The degree to which these effects persist long-term is worth further exploration, as booster sessions or other treatments may be necessary in the future for these patients.
In-Depth [systematic review and meta-analysis]:
This systematic review and meta-analysis included a total of 56 randomized controlled trials (RCTs) and 4,076 participants, which allowed for 265 effect sizes to be obtained.
Eight psychosocial interventions were conducted across RCTs: cognitive therapy, behavior therapy, cognitive behavior therapy (CBT), CBT and additive treatment or augmentation of CBT, supportive or bereavement therapy, combined interventions, psychoeducation, and other psychotherapy. The seven immune system outcomes were proinflammatory cytokines and markers, anti-inflammatory cytokines, immune cell counts, antibodies, viral load, natural killer cell activity, and other outcomes. A priori meta-analysis outcomes included the pretest-posttest-control group effect (ppc g) for the seven immune system outcomes.
This analysis of 56 RCTs found that psychosocial intervention was significantly associated with improved immune function (ppc g = 0.30, 95% CI 0.21 to 0.40; t50.9 = 6.22, p < 0.001). This conclusion is strengthened by low between-study heterogeneity (τ2 = 0.14). Of the immune markers, proinflammatory cytokine or marker levels (ppc g – 0.33, 95% CI 0.19 to 0.48; t25.6 = 4.70, p < 0.001) and immune cell counts (ppc g = 0.29, 95% CI 0.14 to 0.43; t24.0 = 4.03, p < 0.001) were significantly associated with the interventions. In terms of group format, group settings were found to have a significant association with immune outcomes (ppc g = 0.38, 95% CI 0.24 to 0.53; t29.0, p < 0.001) while treatment length did not moderate this association.
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