Cost-utility of collaborative nurse-led self-management support for primary care patients with anxiety, depressive or somatic symptoms: A cluster-randomized controlled trial (the SMADS trial)

Background: Anxiety, depressive and somatoform disorders are highly prevalent and cause a huge economic burden. A nurse-led collaborative care intervention has been set up in order to improve self-management of patients with these mental disorders in primary care in Hamburg, Germany. The aim of this study was to determine the cost-utility of this nurse-led intervention from the health care payer perspective. Methods: This analysis was part of a 12-month cluster-randomized controlled trial aiming to increase perceived self-efficacy of primary care patients with anxiety, depressive or somatic symptoms by collaborative nurse-led self-management support compared with routine care. A cost-effectiveness analysis using quality-adjusted life years was performed. Net-monetary benefit regressions adjusted for baseline differences for different willingness -to-pay thresholds were conducted and cost-effectiveness acceptability curves were constructed. Results: In total, n = 325 patients (intervention group: n = 134; control group: n = 191) with a mean age of 40 from 20 primary care practices were included in the analysis. The adjusted differences in quality-adjusted life years and mean total costs between intervention group and control group were +0.02 and +(sic)1145, respectively. Neither of the two differences was statistically significant. The probability for cost-effectiveness of the complex nurse-led intervention was 49% for a willingness-to-pay of (sic)50,000 per additional quality-adjusted life year. The probability for cost-effectiveness did not exceed 65%, independent of the willingness-to-pay. Conclusion: The complex nurse-led intervention promoting self-management for primary care patients with anxiety, depressive or somatic symptoms did not prove to be cost-effective relative to routine care from a health care payer perspective.