The cost-effectiveness of stepped care for the treatment of anxiety disorders in adults: a model-based economic analysis for the Australian setting

Objective: To evaluate the cost-effectiveness of stepped care compared to care as usual (CAU) for the treatment of adults with mild-to-moderate anxiety disorders from a health sector perspective in the Australian setting. Method: A decision tree model was constructed to estimate the cost per disability adjusted life year (DALY) averted over a 12-month time horizon. The model compared a three-step stepped care intervention to CAU. Stepped care included an initial phase of guided self-help, followed by face-to-face cognitive behavioural therapy, and pharmacotherapy as the final step. The model adopted a health sector perspective, used epidemiological parameters and disability weights obtained from the Global Burden of Disease Study 2013. Effect sizes were derived from a randomized trial of stepped care and a longitudinal cohort study. Costs were expressed in 2013 Australian dollars (A$). Multivariate probabilistic and univariate sensitivity analyses were performed. Results: Stepped care was found to be cost-effective compared to CAU with an incremental cost-effective ratio of A$3093 per DALY averted. One-hundred percent of the uncertainty iterations fell below the A$50,000 per DALY averted willingness-to-pay threshold commonly used in Australia. The evaluation was most sensitive to changes in diagnosis rates and effect sizes. Conclusion: A three-step model of stepped care appears to be cost-effective for the treatment of adults with mild to moderate anxiety disorders from the Australian health sector perspective. These results can provide some assurance to decision-makers that stepped care represents an efficient use of health care resources.