Influence of the characteristics of Japanese patients on the long-term outcomes after aortic valve replacement: results of a microsimulation

OBJECTIVES The aim of this study was to explore the influence of the characteristics of Japanese patients on the long-term outcomes after aortic valve replacement with either mechanical or biological prostheses by means of a microsimulation. METHODS A microsimulation model was used to simulate the lives of patients living in Japan and in the United States after aortic valve replacement. The background mortality data taken from the 21st complete life table of Japan and the bleeding hazard determined from a meta-analysis of long-term results in Japanese institutions were used to simulate Japanese patients. The life expectancy, event-free life expectancy, and lifetime risk of structural valve degeneration were calculated. A sensitivity analysis for various bleeding hazards was performed. RESULTS Regarding the event-free life expectancy, the age crossover points between the two valve types were 64-65 and 57-58 years for Japanese and American patients, respectively. Regarding the life expectancy, the age crossover points were 88-89 and 64-65 years, respectively, for Japanese and American patients. The lifetime risk of structural valve degeneration was higher in Japanese patients than in American patients. The sensitivity analysis showed that the age crossover points were sensitive to the hazard of bleeding complications. CONCLUSIONS The long-term clinical outcomes after aortic valve replacement were simulated with a microsimulation model. The results indicated that the age crossover points in the advantages and disadvantages between mechanical valves and bioprostheses may be higher in Japanese patients than in American subjects.