Concordance of Treatment Effect: An Analysis of The Society of Thoracic Surgeons Intermacs Database

Background: The Society of Thoracic Surgeons (STS) Intermacs Registry represents a real-world data source of durable, left ventricular assist devices that can address knowledge gaps not informed through randomized clinical trials. We sought to compare survival with contemporary left ventricular assist device technologies using multiple analytic approaches to assess concordance of treatment effects and to validate prior STS Intermacs observations. Methods: Patients (≥19 years of age) enrolled into STS Intermacs between August 2017 and June 2019 were stratified by device type (continuous flow, centrifugal left ventricular assist device with hybrid levitation [CF-HL] or full magnetic levitation [CF-FML]). The primary outcome was 1-year survival assessed by 3 statistical methodologies (multivariable regression, propensity score matching, and instrumental variable analysis). Results: Of 4448 patients, 2012 (45.2%) received the CF-HL and 2436 (54.8%) received the CF-FML. One-year survival for the CF-FML was 88% vs 79% for the CF-HL (overall P < .001), with a hazard ratio for mortality of 3.18 for the CF-HL (P < .0001) after risk adjustment. With propensity score matching (n = 1400 each cohort), 1-year survival was 87% for the CF-FML vs 80% for the CF-HL, with a hazard ratio of 3.20 for mortality with the CF-HL (P < .0001) after risk adjustment. With an instrumental variable analysis, the probability of receiving the CF-HL was associated with a hazard ratio of 3.11 (P < .0001). Conclusions: Statistical methodology using propensity score matching and instrumental variable analysis increased the robustness of observations derived from real-world data and demonstrates the feasibility of performing comparative effectiveness research using STS Intermacs. These analyses provide additional evidence supporting a survival benefit of the CF-FML vs CF-HL.