Risk Categories for Myelodysplastic Syndromes: Understanding IPSS-R

Patients with myelodysplastic syndromes (MDS) can be categorized based on how the disease is likely to progress in a process referred to as a risk assessment. This can be used by healthcare professionals to guide treatment decisions, such as when to start treatment, and how intensive treatment should be. The standard tool for risk stratification in patients with MDS is the Revised International Prognostic Scoring System (IPSS-R). IPSS-R is an updated version of the previous IPSS, which was revised to include additional factors to predict outcomes more accurately.

What are the IPSS-R Risk Categories?

IPSS-R classifies patients into one of five categories based on how fast the disease is likely to progress, with the risk categories corresponding to factors associated with increased mortality and an increased likelihood of the disease becoming acute myeloid leukemia (AML). The five categories of IPSS-R are determined based on a risk score:

• Very low-risk: risk score ≤1.5

• Low-risk: risk score >1.5–3

• Intermediate-risk: risk score >3–4.5

• High-risk: risk score >4.5–6 

• Very high-risk: risk score >6.

Patients with lower-risk MDS (very low risk, low risk, and intermediate risk up to 3.5 points) tend to have a milder form of MDS with a better prognosis and fewer symptoms. Treatment for patients with lower-risk MDS generally focuses on managing and improving low blood counts to prevent complications such as bleeding and infections, decreasing the need for blood transfusion, and improving quality of life.

Patients with higher-risk MDS (intermediate risk above 3.5 points, high risk, and very high risk) tend to have more severe symptoms, lower survival rates, and an increased chance of progressing to AML. Patients with higher-risk MDS may need a more aggressive treatment strategy, such as hypomethylating agents or allogeneic hematopoietic stem cell transplantation, to delay disease progression, increase survival rates, and potentially cure the patient. 

The difference in treatment strategies for lower-risk and higher-risk patients highlights the importance of accurately identifying the risk category at diagnosis to provide the most appropriate treatment. It is important to note that IPSS-R does not predict how patients will likely respond to treatment but rather how the disease will behave over time without treatment. 

What are the criteria for each IPSS-R risk category?

IPSS-R is calculated based on five criteria:

1. The percentage of immature blood cells, or blasts, in the bone marrow 
2. Any chromosomal changes present (cytogenetics)
3. Hemoglobin concentration
4. Platelet count
5. Absolute neutrophil count

These factors are chosen due to their impact on survival and likelihood of progression to AML. Each factor is associated with risk score points, which are added up to determine the IPSS-R risk category.

Percentage of blasts in the bone marrow: ≤2% = 0 points, >2–<5% = 1 point, 5–10% = 2 points, >10% = 3 points.

Cytogenetics 

0 points if the only abnormality is −Y, del(11q)

1 point if cytogenetics are normal, del(5q), del(12p), del(20q), del(5q) plus another cytogenetic abnormality

2 points for del(7q), +8, +19, i(17q), any other single or double independent clones

3 points for −7, inv(3)/t(3q), double including −7/del(7q), or complex (3 abnormalities)

4 points if there are more than 3 abnormalities

Hemoglobin concentration (g/dL)

0 points if the hemoglobin is more or equal than ≥10 g/dL

1 point if the hemoglobin is between 8-10 g/dL

1.5 points if the hemoglobin is less than 8.5 g/dL

Platelet count (×109/L of blood) 

0 points if platelets are equal or more than 100 

0.5 points if plateles levels are 50-100

1 point if plateles are less than 50 

Absolute neutrophil count (×109/L of blood)

0 points if neutrophil counts are more than or equal to 0.8

0.5 points if neutrophil counts are less than or equal to 0.8 

What is IPSS-M?

The IPSS-Molecular (IPSS-M) is a newer risk stratification model that incorporates 31 gene mutations, together with the cytogenetic and hematological parameters used in IPSS-R, to determine the risk category. You can learn more about IPSS-M and how it differs from IPSS-R here. 

Key points

• IPSS-R includes five risk categories; very low risk, low risk, intermediate risk, high risk, and very high risk.

• These categories are determined based on a risk score with incorporates bone marrow blast percentage, cytogenetics, hemoglobulin concentration, platelet count, and absolute neutrophil count.

• IPSS-R risk categories help to determine the prognosis, the likelihood of transformation to AML, and the most appropriate treatment strategy. 

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Sources:

1. Revised International Prognostic Scoring System for Myelodysplastic Syndromes. https://ashpublications.org/blood/article/120/12/2454/30571/Revised-International-Prognostic-Scoring-System

2. The International Prognostic Scoring System. https://www.lls.org/myelodysplastic-syndromes/diagnosis/international-prognostic-scoring-system

3. Patient stratification in myelodysplastic syndromes: how a puzzle may become a map. https://ashpublications.org/hematology/article/2020/1/418/474314/Patient-stratification-in-myelodysplastic

4. Molecular International Prognostic Scoring System for Myelodysplastic Syndromes. https://evidence.nejm.org/doi/full/10.1056/EVIDoa2200008