OS based on cytogenetic stratification system and age. OS of 361 patients older than 60 years with AML according to cytogenetic risk group, as assessed using the stratification system generated in this study, and age. Stratification of patients according to the 2 strongest prognostic factors for OS that were evident on multivariate analysis showed that younger patients without high-risk cytogenetics had the best outcome, followed by younger patients with high-risk cytogenetics, older patients without high-risk cytogenetics, and older patients with high-risk cytogenetics.