Comparison to Other Prognostic Indices Designed to Predict TTFT

To explore the ability of the CLL-IPI to predict TTFT relative to other prognostic indices specifically developed to predict this endpoint, we also evaluated the 2011 MDACC score and the O-CLL1 score in this cohort (9,13). The 2011 MDACC score was calculated according to the following formula: I(No. of lymph node sites involved=3) × 7.370 + I(FISH=del11q) × 9.312 + I(FISH=del17p) × 11.285 + (diameter of largest cervical lymph node in cm) × 4.172 + (LDH/100) × I([IGHV gene=mutated] × 5.000 + (LDH÷100) × I(IGHV gene=unmutated)×1.065] + 35.467. The indicator function (I) is equal to 1 if the statement in the parentheses is true and is equal to 0 otherwise(9). The OCLL-1 was defined as the sum of the risk scores of the four individual parameters (i.e., Rai stages, β2-microglobulin, absolute lymphocyte count, mutational status of IGHV). According to the these criteria, 3 different risk categories for TFS were determined: low (score 0–2), intermediate (score 3–5), and high (score 6–7)(13).