Predicting future blood demand from thalassemia major patients in Hong Kong

In Hong Kong, thalassemia major (TM) patients utilized up to 9.5% of blood supply in 2009. For long-term management of blood supply, we predicted the future blood demand of TM patients for the next 10 years.

Annual individual transfusion data in 2005-2009 and demographic information of 381 TM patients were obtained from the Hong Kong Red Cross Blood Transfusion Service database. A generalized estimating equation (GEE) model was fitted to establish the potential relations of blood demand with age, sex, body weight, year of transfusion and splenectomy, accounted for within-patient correlation. The fitted model was used to predict future blood demand for the existing patients by accounting for expected change in body weight and mortality rate. We also predicted the number of new cases in the future based on age- and sex-specific TM incidence and official population projections. Future blood demand was predicted by combining blood demand from the existing and new patients. Female (RR = 0.94, p = 0.006) and history of splenectomy (RR = 0.85, p<0.001) were significantly associated with lower blood demand, while age and weight had an inverted U-shape relation with maximal blood demand at around 24 years of age and 71.8 kg, respectively. We predicted that the total blood demand would increase 0.81% annually from 13,459 units in 2009 to 15,183 units in 2024, with new TM cases accounting for 31.7% of the overall blood demand in 2024.

Our results showed that future annual blood demand from TM patients would steadily increase in the next 10 years. Reducing incidence of TM cases in the future (by improving public education, antenatal care, prenatal diagnosis) and minimizing blood use among existing TM cases (e.g. with hemopoietic stem cell transplantation) can help relieve the burden on management of future blood demand.