Prognosis and Overall Survival of Thalassemia Patients using Semi-Parametric Mixture Cure-Rate Model: a 30-Year Retrospective Cohort Study.

Background: Understanding the determinants of long-term overall survival (OS) of thalassemia patients (TPs) is the mainstay of care.

Methods: As a retrospective survey, we assessed the data of 769 TPs who had regular follow-up and blood transfusion for at least 30 years from 1990 - 2019. We utilized semi-parametric proportional hazards mixture cure-rate regression to discover the factors with a significant effect on short- and long-term OS separately.

Results: The 25- and 30-year OS for the TPs were calculated to be 98.7% and 90.4%, respectively. Each five-year age escalation was associated with a 30% decrease in the probability of being short-term survivors (HR = 1.06, p = 0.047). Parental family relationship influenced both cured (OR = 3.00, p = 0.017) and uncured (HR = 0.50, p = 0.046) TPs. Moreover, the type of iron chelation drug, liver iron concentration, and normal EF results had a significant effect on long-term OS. Aging, parental consanguinity, liver and cardiac siderosis, higher ferritin levels, and low hemoglobin level were associated with poorer prognosis in TPs.

Conclusions: However, deferoxamine followed by multiple drugs as iron chelation, severe liver siderosis, and abnormal EF declined the probability of long-term OS among TPs. This can be considered by health policy decision-makers to enforce the screening program more strictly.