Objective: The standard method of analysing structural valve degeneration (SVD) of biological prostheses is the Kaplan-Meier method. In order to assess SVD with regard to competing risks (e.g. death particularly in elderly patients) cumulative incidence (actual analysis) was compared to Kaplan-Meier (actuarial analysis).
Methods: We retrospectively analysed 257 patients older than 60 years, who underwent mitral valve replacement with different biological prostheses between 1974 and 2000. Reoperation-free survival was determined, both according to Kaplan-Meier and cumulative incidence analysis.
Results: For the total group of patients older than 60 years, the 10- and 15-year freedom from reoperation was 79+/-5 and 55+/-8%, respectively, according to Kaplan-Meier and 90+/-2 and 83+/-3% according to cumulative incidence analysis. For patients older than 65 years of age (n=170), Kaplan-Meier analysis revealed 85+/-7% freedom from reoperation at 10 years vs. 94+/-3% according to cumulative incidence analysis. For those between 60 and 65 years of age (n=87), Kaplan-Meier freedom from reoperation was 76+/-7% at 10 years and 48+/-9% at 15 years vs. 86+/-4 and 75+/-5% according to cumulative incidence analysis.
Conclusions: Kaplan-Meier analysis overestimates the 10- and 15-year risk of SVD compared to cumulative incidence analysis, thus underestimating the benefit of biological valve replacement. Cumulative incidence analysis may lead to a more complete evaluation of risk and benefit and thus better patient management.