Supplementary Material for: Effectiveness of Collaborative Stepped Care for Anxiety Disorders in Primary Care: A Pragmatic Cluster Randomised Controlled Trial

Background: Collaborative stepped care (CSC) may be an appropriate model to provide evidence-based treatment for anxiety disorders in primary care. Methods: In a cluster randomised controlled trial, the effectiveness of CSC compared to care as usual (CAU) for adults with panic disorder (PD) or generalised anxiety disorder (GAD) in primary care was evaluated. Thirty-one psychiatric nurses who provided their services to 43 primary care practices in the Netherlands were randomised to deliver CSC (16 psychiatric nurses, 23 practices) or CAU (15 psychiatric nurses, 20 practices). CSC was provided by the psychiatric nurses (care managers) in collaboration with the general practitioner and a consultant psychiatrist. The intervention consisted of 3 steps, namely guided self-help, cognitive behavioural therapy and antidepressants. Anxiety symptoms were measured with the Beck Anxiety Inventory (BAI) at baseline and after 3, 6, 9 and 12 months. Results: We recruited 180 patients with a DSM-IV diagnosis of PD or GAD, of whom 114 received CSC and 66 received usual primary care. On the BAI, CSC was superior to CAU [difference in gain scores from baseline to 3 months: -5.11, 95% confidence interval (CI) -8.28 to -1.94; 6 months: -4.65, 95% CI -7.93 to -1.38; 9 months: -5.67, 95% CI -8.97 to -2.36; 12 months: -6.84, 95% CI -10.13 to -3.55]. Conclusions: CSC, with guided self-help as a first step, was more effective than CAU for primary care patients with PD or GAD.