Expressive suppression of emotion is a moderator of anxiety in a unified protocol for transdiagnostic treatment of anxiety and depressive disorders: A secondary analysis

•Pre-treatment high ES of emotion reduces the efficacy of not only CBT but also UP.•UP is effective for improving anxiety symptoms in patients with high ES.•Interventions intended to improve ES may improve the efficacy of UP.•An optimal degree of ES, rather than simply high or low ES, should be considered.•Cultural differences should be considered for optimal degrees of ES. Expressive suppression (ES) of emotion is considered a moderator that reduces the efficacy of cognitive behavioural therapy (CBT); however, whether and how ES moderates the efficacy of the unified protocol for transdiagnostic treatment of emotional disorders (UP), a version of CBT targeting aversive/avoidant responses to emotions, including ES, remain unclear. We investigated whether and how emotion regulation, especially ES, moderates UP efficacy for anxiety symptoms in patients with anxiety and depressive disorders. We conducted a secondary analysis of data from a previous trial. Seventeen patients with anxiety and/or depressive disorders were included. Changes (slope estimates) in the Structured Interview Guide for the Hamilton Anxiety Rating Scale from pre-treatment to post-treatment were measured using a latent growth curve model with empirical Bayesian estimation. Pre-treatment ES, cognitive reappraisal, and depressive symptoms were used as slope factor predictors. Only pre-treatment ES significantly predicted the slope in the latent growth curve model (estimate value = 0.45; standard deviation = 0.21; 95% credible interval = 0.03–0.87, one-tailed p-value = 0.004), and an inverse correlation between pre-treatment ES levels and improvement magnitude of anxiety symptoms was demonstrated. Because the data were obtained from a single-arm trial, this study did not have controls, and most participants received pharmacotherapy in addition to UP. Therefore, generalisability of the present findings might be compromised. Low ES before UP was an effective predictor of greater improvement in anxiety symptoms after UP. The findings suggest that interventions intended to improve ES may improve UP efficacy.