Disease-free survival (DFS) according to the WBC index.

The WBC index, calculated as the product of WBC by the ratio of marrow blasts at diagnosis, was available for 150 of the 154 patients reaching a complete remission. DFS differed significantly among the three WBC index subgroups (low WBC index < 2.5; intermediate WBC index between 2.5 and 20; high WBC index of 20 or more) (P = .0015, by the log-rank test).