(PS3-78) Navigating Complexity: Impact of Comorbidity on Long Term Outcomes Following Cognitive Behavioural Therapy for Anxiety Disorders

Cognitive behavioural therapy (CBT) is the first line treatment for anxiety and related disorders. Yet, limited research has investigated long term outcomes following CBT and available research utilizes short follow up periods and highly screened participants. The comorbidity of psychiatric conditions is common, but the current literature limits generalizability to real-world clients receiving CBT in the community. This study examined long term outcomes after group CBT for generalized anxiety disorder (GAD), social anxiety disorder (SAD), and posttraumatic stress disorder (PTSD) in a community sample. Changes in symptoms pre- to post-treatment and over a 2-year follow up period were examined, as well as the influence of number of diagnoses and depressive symptoms on trajectories of change over time. Data was collected at the Anxiety Treatment and Research Clinic at St. Joseph’s Healthcare Hamilton. Worry, social anxiety, and posttraumatic stress symptoms were assessed at pre- and post-treatment and 3-, 6-, 9-, 12-, and 24-months. The sample size at pre- and post-treatment was GAD (N=301 pre-tx; N=139 post-tx), SAD (N=299 pre-tx; N=132 post-tx), and PTSD (N=274 pre-tx; N=137 post-tx). Attrition was observed over the follow up period. Compared to individuals continuing with the follow up, individuals who dropped out during the follow up period displayed no significant differences in their symptom severity at post-treatment (i.e., trajectories of change over the follow up include individuals with varied symptom severity at post-treatment). Analyses were completed using linear mixed effects modeling. Individuals with GAD, SAD, and PTSD demonstrated significant symptom improvement pre- to post-treatment. Higher levels of depression pre-treatment were associated with greater GAD (β=0.34 (SE=0.045), p< 0.0001), SAD (β=0.36 (SE=0.048), p< 0.0001), and PTSD (β=0.47 (SE=0.044), p< 0.0001) symptoms throughout treatment. A higher number of diagnoses was also associated with greater GAD (β=0.15 (SE=0.044), p=0.0009) and SAD (β=0.12 (SE=0.047), p=0.0093) symptoms throughout treatment. Specifically for GAD, a greater number of diagnoses was associated with diminished symptom reduction pre to-post treatment (β=0.069 (SE=0.032), p=0.034). Symptom reduction was maintained over the follow up for all disorders, suggesting a low risk of relapse, though attrition was high across the follow up period. Greater pre-treatment levels of depression were associated with greater GAD (β=0.31 (SE=0.068), p< 0.0001), SAD (β=0.19 (SE=0.080), p=0.020), and PTSD (β=0.24 (SE=0.076), p=0.0018) symptoms across follow up, but number of diagnoses did not impact maintenance of gains over the follow up period. This study provides preliminary evidence for the long-term efficacy of CBT in naturalistic settings, suggesting we are making a meaningful difference for individuals in our communities that seek CBT treatment for GAD, SAD, and PTSD. It is important clinicians consider the impact of comorbidity, specifically for GAD, as well as the impact of depressive symptoms which may attenuate progress throughout treatment.