Overall and leukemia free survival is shortest in people with myelofibrosis who experience severe thrombocytopenia, according to a study involving nearly 1,300 individuals. Investigators looked at the significance of low platelets in participants who had primary myelofibrosis (PMF; n=877), post-essential thrombocythemia (PET-MF; n=180), or post-polycythemia vera myelofibrosis (PPV-MF; n=212). Among the results:

• 11% of patients had platelets <50 x109 /L.
• 14% had platelets between 50-100 x109 /L.
• Patients with lower platelets were the most anemic and transfusion dependent, had the highest blast count, and unfavorable karyotype.
• Overall and leukemia free survival in these patients were 15 and 13 months, respectively.
• Acute leukemia incidence was nearly twice as high as in other participants (6.9 vs 3.6 cases/100 person-years).

The authors noted that their findings apply mainly to patients with PMF, since those with PEV or PVT-MF have already inferior prognosis with platelets <100 x 109 /L.