Prognosis

Patients aged under 60 years have a better survival rate than older patients. Specific prognostic criteria were defined by the International Prognostic Scoring System (IPSS) working group in 1997 after a multivariate analysis of 816 patients with de novo MDS who were treated primarily with supportive care.[66] The IPSS uses three factors (number of cytopenias [1, 2, or 3], percentage marrow blasts [<5, 5% to 10%, 11% to 20%, or 21% to 30%], and cytogenetic abnormalities [good-, intermediate-, or poor-risk karyotype]) to categorise patients into four overall risk groups for AML progression or death: low-, intermediate-1 (INT-1), INT-2, and high-risk disease. For older patients, overall median survival by risk group ranges from less than 6 months for high-risk patients to 5.7 years for low-risk patients.[66] Secondary MDS has a poorer prognosis.[3] Chromosome 5q31 deletion (del(5q)), monosomy 7, 11q23, and TP53 mutations all have a poor prognosis.[93]

One of the major drawbacks of the 1997 IPSS is that it included patients with 21% to 30% blasts in the bone marrow, a group that is classified as having AML in the WHO classification.[65] Another limitation is that the number of cytogenetic subgroups in the intermediate karyotype risk category is large, and the actual prognostic significance of these is diverse. Nonetheless, the IPSS serves as a useful guide when discussing prognosis with patients and families.

Revised International Prognostic Scoring System (IPSS-R)[63]

The IPSS-R was developed to address some of the drawbacks of the IPSS. This IPSS-R scoring system includes five variables:

  • Bone marrow blast percentage:

    • ≤2 (0 points)

    • >2 to <5 (1 point)

    • 5-10 (2 points)

    • >10 (3 points).

  • Karyotype:

    • Very good (0 points): deletion Y or del(11q)

    • Good (1 point): normal karyotype, del (5q), del(12p), del (20q), a double abnormality, including del(5q)

    • Intermediate (2 points): deletion 7q, +8, +19, i(17q), and any other single or double independent clones

    • Poor (3 points): deletion 7, inv(3)/t(3q)/del(3q), double abnormalities including -7/del(7q), or three abnormalities

    • Very poor (4 points): complex karyotype (≥3 abnormalities).

  • Haemoglobin level:

    • ≥10 g/dL (0 points)

    • 8 to <10 g/dL (1 point)

    • <8 g/dL (1.5 points).

  • Platelet count:

    • ≥100,000/microlitre (0 points)

    • 50,000 to 100,000/microlitre (0.5 points)

    • <50,000/microlitre (1 point).

  • Absolute neutrophil count:

    • ≥800/microlitre (0 points)

    • <800/microlitre (0.5 points).

The IPSS-R score is calculated by adding each of these five values, and is divided into five groups based on the risk of AML development and overall survival. The IPSS-R was first validated in a set of 7012 patients with primary MDS. The five risk groups are:

  • Very low risk: ≤1.5

  • Low risk: >1.5 to 3.0

  • Intermediate risk: >3.0 to 4.5

  • High risk: >4.5 to 6.0

  • Very high risk: >6.

Median survival (without treatment) for the IPSS-R risk groups are:

  • Very low risk: 8.8 years

  • Low risk: 5.3 years

  • Intermediate risk: 3 years

  • High risk: 1.6 years

  • Very high risk: 0.8 years.

Time to 25% AML evolution for the IPSS-R risk groups are:

  • Very low risk: not reached

  • Low risk: 10.8 years

  • Intermediate risk: 3.2 years

  • High risk: 1.4 years

  • Very high risk: 0.7 years.

Molecular International Prognostic Scoring System (IPSS-M)[62]

The IPSS-M is a refined version of the IPSS and IPSS-R that combines somatic mutations (of 31 genes) with haematological and cytogenetic parameters to risk stratify patients with MDS. The IPSS-M classifies MDS patients into the following six risk groups based on a risk score derived from clinical (bone marrow blast percentage, platelet count, haemoglobin level), cytogenetic, and genetic prognostic factors (calculated using a web-based tool:  IPSS-M risk calculator Opens in new window):

  • Very low risk (risk score: ≤-1.5)

  • Low risk (risk score: >-1.5 to -0.5)

  • Moderate low risk (risk score: >-0.5 to 0)

  • Moderate high risk (risk score: >0 to 0.5)

  • High risk (risk score: >0.5 to 1.5)

  • Very high risk (risk score: >1.5).

Median overall survival for the IPSS-M risk groups are:

  • Very low risk: 10.6 years

  • Low risk: 6.0 years

  • Moderate low risk: 4.6 years

  • Moderate high risk: 2.8 years

  • High risk: 1.7 years

  • Very high risk: 1.0 years.

Risk of transformation to AML by 1, 2, and 4 years for the IPSS-M risk groups are:

  • Very low risk: 0%, 1.2%, and 2.8%, respectively

  • Low risk: 1.7%, 3.4%, and 5.1%, respectively

  • Moderate low risk: 4.9%, 8.8%, and 11.4%, respectively

  • Moderate high risk: 9.5%, 14%, and 18.9%, respectively

  • High risk: 14.3%, 21.2%, and 29.2%, respectively

  • Very high risk: 28.2%, 38.6%, and 42.8%, respectively.

Risk of death without AML by 1, 2, and 4 years for the IPSS-M risk groups are:

  • Very low risk: 2.2%, 7%, and 15.9%, respectively

  • Low risk: 8.5%, 16.2%, and 29.5%, respectively

  • Moderate low risk: 12%, 19.8%, and 33.6%, respectively

  • Moderate high risk: 18%, 31.1%, and 51.1%, respectively

  • High risk: 19.3%, 39.8%, and 54.2%, respectively

  • Very high risk: 30.6%, 45.6%, and 51.3%, respectively.

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