The Unified Protocol compared with diagnosis-specific protocols for anxiety disorders: 12-month follow-up from a randomized clinical trial

Abstract Objective To examine whether the Unified Protocol (UP) remains equivalent to single-disorder protocols (SDPs) in the treatment of anxiety disorders at 12-month follow-up. Method We report results from the 12-month follow-up of a recent randomized equivalence trial (Barlow et al., 2017 [ 1 ]). Data are from 179 participants (55.31% female sex, 83.24% White, average age 30.66) who met criteria for a principal anxiety disorder and were randomized to either the UP or SDP conditions. Consistent with the parent trial, the primary outcome was principal diagnosis clinician severity rating (CSR) from the Anxiety Disorder Interview Schedule (ADIS). Secondary outcomes included anxiety, depression, and impairment. Missing data were accommodated using multiple imputation (10,000 imputed data sets) under a missing at random assumption. Equivalence between the UP and SDPs was tested using slope difference scores from latent growth models and 95% confidence interval of between-condition effect sizes. Results The results indicated that the UP and SDP conditions remained equivalent with regard to principal diagnosis clinician severity rating at 12-month follow-up. In addition, there were no significant differences between conditions on secondary outcomes at 12-month follow-up. Conclusions The UP continues to yield outcomes comparable to SDPs at 12-month follow-up, and therefore provides a single intervention that can be used to treat the most commonly occurring psychiatric disorders with durable effects.