Sokal Index for Chronic Myelogenous Leukemia (CML)

Why Use

NCCN guidelines for CML treatment recommend use of the Sokal and Hasford Scores over EUTOS for clinical risk stratification. The Sokal Score is also preferentially used in clinical trials so that comparisons can be made to prior trials.

When to Use

In the US, the Sokal Score can be used to determine risk and decide on therapy based on the NCCN guidelines for CML . While the EUTOS score is easier to calculate and more accurately identifies high risk patients in the era of tyrosine kinase inhibitors, it has not been adopted by the NCCN guidelines.

Formula

Pearls / Pitfalls

The Sokal Index, also referred to as the Sokal Score, was developed using patients treated in the pre-tyrosine kinase inhibitor era and thus can not necessarily be applied today. Survival outcomes have drastically improved since then. Although scores are stratified into low, intermediate, and high risk, some studies have shown that low and intermediate risk have similar outcomes. Some advocate combining the Sokal and EUTOS Scores for better predictive value.

Management

Although the Sokal Score has limited usefulness outside of clinical trials today, in general, low and intermediate risk patients can be started on standard dose imatinib, and high risk patients should be considered for newer generation TKIs or be monitored more closely to ensure complete molecular response.

Critical Actions

Can only be applied in a newly-diagnosed patient prior to starting therapy.

Advice

Whether the patient meets milestones for cytogenetic and molecular response is more predictive of outcome once therapy is started.

More Information

Interpretation: Risk Group Sokal Score 2-year Survival Median Survival Low <0.8 90% 5 years Intermediate 0.8–1.2 65-90% 2.5-5 years High >1.2 65% 2.5 years