Quantitative and qualitative differences in use and trends of hematopoietic stem cell transplantation: a Global Observational Study

Abstract

Fifty-five years after publication of the first hematopoietic stem cell transplantation this technique has become an accepted treatment option for defined hematologic and non-hematologic disorders. There is considerable interest in understanding differences in its use and trends on a global level and the macro-economic factors associated with these differences. Data on the numbers of hematopoietic stem cell transplants performed in the 3-year period 2006-2008 were obtained from Worldwide Network for Blood and Marrow Transplantation member registries and from transplant centers in countries without registries. Population and macro-economic data were collected from the World Bank and from the International Monetary Fund. Transplant rates were analyzed by indication, donor type, country, and World Health Organization regional offices areas and related to selected health care indicators using single and multiple linear regression analyses. Data from a total of 146,808 patients were reported by 1,411 teams from 72 countries over five continents. The annual number of transplants increased worldwide with the highest relative increase in the Asia Pacific region. Transplant rates increased preferentially in high income countries (P=0.02), not in low or medium income countries. Allogeneic transplants increased for myelodysplasia, chronic lymphocytic leukemia, acute leukemias, and non-malignant diseases but decreased for chronic myelogenous leukemia. Autologous transplants increased for autoimmune and lymphoproliferative diseases but decreased for leukemias and solid tumors. Transplant rates (P<0.01), donor type (P<0.01) aand disease indications (P<0.01) differed significantly between countries and regions. Transplant rates were associated with Gross National Income/capita (P<0.01) but showed a wide variation of explanatory content by donor type, disease indication and World Health Organization region. Hematopoietic stem cell transplantation activity is increasing worldwide. The preferential increase in high income countries, the widening gap between low and high income countries and the significant regional differences suggest that different strategies are required in individual countries to foster hematopoietic stem cell transplantation as an efficient and cost-effective treatment modality.

Figure 1.

Transplant rates for the total number of HSCT in participating countries by WHO regional offices area for the years 2006–2008. Regions are colored by WHO regional offices area code (see text). Shades of colors reflect transplant rates (numbers of HSCT, allogeneic and autologous combined, by 10 million inhabitants).

Figure 2.

Indications and donor types of 146,808 HSCT by World Bank category in the years 2006–2008. The figure reflects the relative proportions of allogeneic (blue) or autologous (red) HSCT (left three columns), of allogeneic donor type [family donor (green) or unrelated donor (blue)] (central left three columns), main indications for allogeneic HSCT (central right three columns), and main indications for autologous HSCT (right three columns; for color code see figure) by low, middle of high income according to World Bank category. For definitions see the Design and Methods section. NM: non-malignant disorders; ST: solid tumors; LPD: lymphoproliferative disorders; Leuk: leukemia.

Figure 3.

Transplant rates and Gross National Income per capita (GNI/cap). (A) Transplant rates for allogeneic and autologous HSCT by WHO regional offices area, donor type and GNI/cap. Symbols reflect transplant rates (TR; numbers of HSCT by 10 million inhabitants) in participating countries and the respective lnGNI/cap. Colors indicate WHO region (see Figure 1); squares indicate allogeneic HSCT, triangles autologous HSCT. Vertical lines separate countries by World Bank (WB) category. (B) Transplant rates for allogeneic HSCT for acute leukemia and non-malignant disorders by WHO regional offices areas and GNI/cap. Symbols reflect transplant rates (TR; numbers of HSCT by 10 million inhabitants) in participating countries and the respective lnGNI/cap. Colors indicate WHO regional offices areas (see Figure 1); squares indicate acute leukemia, triangles non-malignant disorders. Vertical lines separate countries by World Bank category. (C) Unrelated donor transplant rates by WHO regional offices areas, GNI/cap and presence of an unrelated donor registry. Symbols represent transplant rates; open symbols indicate absence of an unrelated donor registry, full symbols the presence of such a registry and size of symbols numbers of its registered donors. Colors indicate WHO region (see Figure 1). Only countries with unrelated donor HSCT are included. (D) Change in transplant rates (all transplants) from 2006 to 2008 by GNI/cap and WHO regional offices areas. Symbols represent increase or decrease in transplant rates (TR) from 2006 to 2008; colors indicate WHO regional offices areas (see figure 1).

Figure 4.

Total HSCT in 2006 and relative increase or decrease (in %) in 2007 and 2008 according to (A) donor type, (B) WHO region, (C) World Bank Category (high, medium and low income by GNI/capita), (D) autologous transplant indication, (E) allogeneic transplant indication and (F) allogeneic stem cell source