Co-plots of Kaplan-Meier estimates of survival in CLL. One-hundred and twenty-seven patients were separated into 4 groups based on their TPO and β₂-microglobulin (B2M) levels. The solid line represents the Kaplan-Meier estimates of overall survival for each group. The 95% confidence intervals of the survival curves are presented using the dotted lines. Each tick mark represents the time at which patients were censored.