Predicting future blood demand in Thalassemia patients in Hong Kong Chinese

Abstract

BACKGROUND: Increasing blood demand is well observed in almost all parts of the world with longer longevity and hence more blood transfusion for chronic illnesses, surgical and orthopaedic procedures and cancer treatment. Although incidence of genetic diseases like thalassaemia major should diminish with better antenatal diagnosis, but their survival has been significantly improved with more medical treatment and transfusion support. We are interested at this small number of patients that utilizing about 10% of blood supply in Hong Kong annually. By looking at their annual demand pattern, age and medical status, we derive model to forecast their blood demand from 2010 to 2019. METHODS: Annual transfusion data in 2005–2009 and demographic information of 382 thalassemia patients were obtained from Hong Kong Red Cross Blood Transfusion Service database. A generalized estimating equation (GEE) model was fitted to establish the relation between age, sex, body weight, year of transfusion and splenectomy with blood demand, adjusted for within-patient correlation. Future blood demand for the existing patients was predicted based on the fitted model accounted for expected change in body weights for patients under 20 years according to the US CDC growth curve [1]. We also derived the age and sex-specific incidence of thalassemia from data in 2006–2009 and predict future new cases based on the projected Hong Kong population from Census and Statistics Department [2]. The future blood demand from these cases was predicted based on the fitted GEE model. The combined blood demand from the existing and new patients gives the total predicted blood demand. RESULTS: Three hundred and eighty-two thalassemia patients were retrieved to construct the GEE model and 10 patients were excluded due to intermittent blood consumption in 2005–2009. Female and splenectomy significantly associated with a lower blood demand, while age and weight have an inverted U-shape relation with maximal blood demand at around 24 years old and 66.3 kg respectively. After adjusted for these factors, no significant time trend was found. The total blood demand in 2005 was 12,442 units and has a 2.4% annual increase to 13,668 units in 2009. For these existing patients, blood demand is predicted to increase to 13,931.1 units (prediction interval, PI = 13,191.2–14,670.9) in 2014 then decrease to 13,382.6 units (PI = 12,671.3–14,093.9) in 2019. By including all new patients, blood demand is predicted to increase from 13,668 units in 2009 to 16,423.6 units (confidence interval = 14,959.1–17,888.2) in 2019 at an annual rate of 1.85%. CONCLUSIONS: The results show that the future annual blood demand in thalassemia patients will increase by 20.2% to 16,423.6 units in 2019. Reducing incidence of new thalassemia cases through public education, antenatal care, prenatal diagnosis, minimizing blood use in existing cases with hemopoietic stem cell transplantation or splenectomy may help better management of future blood demand.