# IPSET-thrombosis score (essential thrombocythaemia)

Source: https://onco.cc/terms/ipset-thrombosis/  
OnCo record `ipset-thrombosis` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Essential thrombocythaemia rarely shortens life, so treatment is about preventing clots: the IPSET-thrombosis score combines age over 60, a previous clot and the JAK2 mutation to sort patients into very low, low, intermediate and high risk, and only the higher groups take a platelet-lowering drug.

## Summary

What is measured: the risk of arterial or venous thrombosis, the main harm of essential thrombocythaemia. How: three items from the history and one blood test: age over 60, a previous thrombosis, cardiovascular risk factors (in the original score) and JAK2 V617F status by PCR. The revised IPSET-thrombosis (2015) defines very low risk (60 or under, no thrombosis, JAK2-negative), low (JAK2-positive only), intermediate (over 60 only) and high (any prior thrombosis, or over 60 with JAK2). The platelet count itself is not in the score, although counts above 1,000 to 1,500 x 10^9/L raise bleeding risk through acquired von Willebrand deficiency, and CALR-mutated patients clot less often. What a result changes: very low risk is observed, or given aspirin if cardiovascular risk factors are present; low risk gets low-dose aspirin; intermediate risk gets aspirin with cytoreduction considered; high risk gets cytoreduction (hydroxyurea first line, anagrelide, or interferon in younger patients and pregnancy) plus aspirin, and anticoagulation after a venous clot. Where it matters: essential thrombocythaemia.

## Fields

- Kind: Term
- Last checked: 2026-09-17
- Also known as: IPSET; IPSET-thrombosis; revised IPSET-thrombosis; r-IPSET; ET thrombosis risk; very low risk ET; low-risk ET; intermediate-risk ET; high-risk essential thrombocythaemia

## Connected records

- terms: [MPN driver mutations (JAK2 V617F, CALR, MPL) and allele burden](https://onco.cc/terms/mpn-driver-mutations/)
- targets: [JAK2](https://onco.cc/targets/jak2/)
- drugs: [Anagrelide](https://onco.cc/drugs/anagrelide/), [Aspirin](https://onco.cc/drugs/aspirin/), [Hydroxyurea (hydroxycarbamide)](https://onco.cc/drugs/hydroxyurea/), [Interferon alfa-2a/2b](https://onco.cc/drugs/interferon-alfa/)
- cancers: [Essential thrombocythaemia (ET)](https://onco.cc/cancers/essential-thrombocythaemia/)

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JSON: https://onco.cc/api/v1/entities/ipset-thrombosis.json