Risk Factors in Myelofibrosis Linked With Poor Outcome After Splenectomy

Survival of patients with myelofibrosis (MF) who undergo splenectomy is adversely affected by older age, the need for transfusion, and leukocyte and circulating blast cell counts, according to a new analysis. The findings, and a score developed to assess risk, may help identify the best candidates for splenectomy.

“Indications for splenectomy in MF include drug-refractory symptomatic splenomegaly, frequent transfusion need, refractory thrombocytopenia, and complications from portal hypertension,” wrote study authors led by Ayalew Tefferi, MD, of the Mayo Clinic in Rochester, Minnesota. Splenectomy can offer symptomatic relief and improvement in anemia and thrombocytopenia, but also carries the risk of complications including perioperative bleeding, infections, and thrombosis.

Researchers analyzed results from 120 consecutive patients with MF who underwent splenectomy in order to determine the best candidates for the procedure. The results were published online ahead of print in the American Journal of Hematology.

At the time of splenectomy, patients had a median age of 66 years, and 58% were male. Most patients (61%) were red cell transfusion dependent, 49% had a platelet count < 100 × 10⁹/L, and 13% had circulating blasts ≥ 5%. Over a median follow-up from the time of splenectomy of 1.3 years, there were 95 deaths (79%), 30 leukemic transformations (25%), and 34 thrombotic events (28%).

On a multivariate analysis, several factors were found to be significantly associated with poorer survival after splenectomy. These included age above 65 years, with a hazard ratio (HR) of 1.8 (95% CI, 1.2–2.7); leukocyte count > 25 × 10⁹/L, with an HR of 2.1 (95% CI, 1.3–3.4); circulating blasts ≥ 5%, with an HR of 2.3 (95% CI, 1.3–4.2); and red cell transfusion need, with an HR of 2.4 (95% CI, 1.5–3.7).

The investigators created a scoring system based on these risk factors. Patients with 3 or 4 of those factors were deemed high-risk, and these patients had an HR for mortality after splenectomy of 5.9 (95% CI, 3.2-10.9), compared to the lowest risk group with 0 to 1 factors). Those with two risk factors were intermediate risk, and had an HR for mortality of 2.9 (95% CI, 1.8-4.6), compared to the low-risk group.

“The presence of 3 or more of these 4 risk factors was associated with an extremely poor outcome with median survival of less than 6 months, and no patients surviving for 3 years after splenectomy,” the authors wrote. “Therefore, it might be more appropriate to offer alternative therapy for such patients.”