Myelofibrosis and Essential Thrombocythemia Observational Study (MOST)

Inclusion Criteria:

- MF cohort: Diagnosis of MF and low-risk using DIPSS risk categorization OR
intermediate-1 risk by DIPSS by reason of age alone.

- ET cohort: Diagnosis of ET and age ≥ 60 years OR history of thromboembolic events OR
currently receiving ET-directed therapy (eg, hydroxyurea, anagrelide, interferon,
busulfan, ruxolitinib, etc).

- Willing and able to provide written informed consent.

- Willing and able to complete patient assessment questionnaires either alone or with
minimal assistance from a caregiver and/or trained site personnel.

- Under the supervision of a physician for the current care of MF or ET.

Exclusion Criteria:

- Individuals who are participating in blinded investigational drug studies.

- Individuals who are participating in Incyte investigational/interventional drug trials
(company- or investigator-sponsored studies) until they have completed the 30-day end
of study visit.

- Life expectancy ≤ 6 months.

- Diagnosis of secondary acute myeloid leukemia, myelodysplastic syndrome, chronic
myelogenous leukemia, or secondary thrombocytosis.