Geographic Variation in the Use of Continuous Outpatient Inotrope Infusion Therapy and Beta Blockers

Background: Continuous outpatient inotrope infusion therapy (COIIT) can be used as palliative or interim treatment in patients with advanced heart failure (AHF).  Despite widespread use, there is a relative lack of data informing best practices. This study aimed to examine whether patterns of COIIT use differed by region and to explore whether observed differences influenced clinical outcomes. Methods: Retrospective study of AHF patients receiving COIIT from May 2009 through June 2016. The primary outcome was regional difference, the secondary outcome was persistence (duration) on therapy. Regions were compared using chi square. Cox proportional hazards model was used to calculate hazard ratios for treatment regimens. Results: There were 3,286 patients, mean (SD) age 61.9 (14.4) years and 74.0% (2,433) male. Inotrope selection and beta blocker use varied by region (χ2 (21) = 166.9, p < 0.001).  Persistence was greater on milrinone compared to dobutamine (HR (for discontinuation) 0.54, CI 0.41-0.70, p < 0.001).  Concurrent beta-blocker was associated with greater persistence for patients receiving milrinone (HR 0.13, CI 0.08-0.20, p < 0.001) and dobutamine (HR 0.36, CI 0.18-0.71, p < 0.001). Conclusions: Patterns of COIIT use varied by region, and variations in use were associated with differences in clinical outcomes.