Method:Participants (n = 386) with GAD participated in 12 sessions of group CBT at an out-patient clinic. Of those who provided at least partial data (n = 326), 84.5% completed treatment. Most questionnaires were completed at pre- and post-treatment; worry severity was assessed weekly.
Results:Group CBT led to improvements in chronic worry (d = –0.91, n = 118), depressive symptoms (d = –1.22, n = 172), GAD symptom severity (d = –0.65, n = 171), intolerance of uncertainty (IU; d = –0.46, n = 174) and level of functional impairment (d = –0.35, n = 169). Greater pre-treatment GAD symptom severity (d = –0.17, n = 293), chronic worry (d = –0.20, n = 185), functional impairment (d = –0.12, n = 292), and number of comorbid diagnoses (d = –0.13, n = 299) predicted greater improvement in past week worry over treatment. Biological sex, age, depression symptom severity, number of treatment sessions attended, and IU did not predict change in past week worry over time.