Which scores are used to determine the prognosis for chronic myelogenous leukemia (CML)?

Updated: May 23, 2021
  • Author: Emmanuel C Besa, MD; Chief Editor: Sara J Grethlein, MD, FACP  more...
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One widely used prognostic index, the Sokal score, is calculated for patients aged 5-84 years by the following equation:

Hazard ratio = exp 0.0116 (age - 43) + 0 .0345 (spleen size [cm below costal margin] - 7.5 cm) + 0.188 [(platelet count/700)2 - 0.563] + 0.0887 (% blasts in blood - 2.1)

The three categories of the Sokal score are as follows:

  1. Low risk: score < 0.8
  2. Intermediate risk: score 0.8-1.2
  3. High risk: score > 1.2

The Sokal score correlates with the likelihood of achieving complete cytogenetic response, as follows:

  • Low-risk patients: 91%
  • Intermediate-risk patients: 84%
  • High-risk patients: 69%

Since the advent of the Sokal score, two other CML prognostic scores have been developed: the Hasford score in the 1990s and the EUTOS (European Treatment and Outcome Study) score in the 2000s. Like the Sokal score, the Hasford formula categorizes patients into low-, intermediate- and high-risk groups; the EUTOS score differentiates only between high-risk and low-risk groups. The Hansford score, which also incorporates peripheral blood eosinophils and basophils as a percentage of total leukocytes, may be more accurate at discriminating between low-risk and intermediate-risk CML, and so may be useful in predicting molecular response to initial TKI treatment of patients with chronic-phase CML. [13]

Online calculators of these scores are available. See the Sokal Score for CML and Calculation of Relative Risk of CML Patients.

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