What is the Sokal score?

The Sokal prognostic index is a formula published in 1984 by Sokal et al. that uses age, spleen size, platelet count, and blast percentage to predict survival in chronic myelogenous leukemia. It remains widely used alongside the EUTOS and Euro scores.

What are the risk cut-offs?

Low risk: score 1.2. Higher scores correlate with shorter survival and lower rates of complete cytogenetic response.

How is spleen size measured?

Spleen size in the Sokal formula is the palpable distance in centimeters below the left costal margin. Enter 0 if the spleen is not palpable on physical examination.

Does the Sokal score apply to patients on TKIs?

The Sokal score was derived from chemotherapy-era data (busulfan/hydroxyurea). It still predicts response to imatinib and second-generation TKIs, but the EUTOS long-term survival (ELTS) score is preferred for the TKI era per some guidelines.

What platelet unit does the formula use?

The formula uses platelets in units of 10⁹/L (same as 10³/µL or thousands/µL). A typical normal value is 150–400 × 10⁹/L.

Sokal CML Prognostic Score

Name: Sokal CML Prognostic Score
Availability: InStock
Author: Nham Vu

Enter age, spleen size, platelet count, and blast percentage to get the Sokal score and CML risk group.

Patient Parameters

Age (years)

Spleen size (cm below costal margin; 0 if not palpable)

Platelet count (× 10⁹/L)

Peripheral blood blasts (%)

Enter patient values and click Calculate to see the Sokal score.

Sokal Formula

Score = exp(0.0116 × (age − 43.4))
         × (0.0345 × (spleen − 7.51))
         × (0.188 × ((platelets/700)² − 0.563))
         × (0.0887 × (blasts − 2.10))

Low risk: Score < 0.8

Intermediate risk: Score 0.8 – 1.2

High risk: Score > 1.2

Done

Summary