A new stratification strategy that identifies a subset of class III patients with an adverse prognosis among children with β thalassemia major undergoing a matched related allogeneic stem cell transplantation

Abstract

One hundred ninety patients underwent 197 HLA-matched related allogeneic stem cell transplantation for a diagnosis of β thalassemia major at our center. The median age (±SD) was 7 ± 4.1 years, and there were 129 (68%) males. Age and liver size as continuous variables were significantly associated with an adverse outcome. Using a receiver operator characteristics curve plot analysis, cutoff values of 7 years and 5 cm for age and liver size, respectively, were associated with the highest likelihood ratio of an adverse impact. On a multivariate analysis age ≥7 years and liver size ≥5 cm had a significant impact on event free survival (EFS) (relative risk 2.2 and 2.7, P values .014 and .000, respectively). Using these 2 variables, patients were categorized as high risk if they were ≥7 years and had a liver size ≥5 cm (n = 41; all belonged to Class III). The 5-year EFS and overall survival (OS) in this high-risk group was 23.93 ± 6.88 and 39.01 ± 7.96, whereas in the remaining Class III patients (n = 64) it was 70.3 ± 6.06 and 78.3 ± 5.5, respectively. This risk stratification identifies a significant subset (39%) of patients among those in Class III who have a poor outcome with a conventional myeloablative allogeneic stem cell transplantation. Patients in this high-risk group would probably benefit from novel therapeutic approaches.