Predictability of hematopoietic stem cell transplantation rates

Background and Objectives Hematopoietic stem cell transplantation (HSCT) is a complex and expensive procedure. Trends in the use of this procedure have appeared erratic in the past. Information on future needs is essential for health care administrators.

Design and Methods We analyzed the evolution of transplant rates, e.g. numbers of transplants per 10 million inhabitants, in Europe from 1990 to 2004 for all major disease categories and used Gross National Income (GNI) per capita, team density (numbers of teams per 10 million inhabitants) and team distribution (numbers of teams per 10,000 km2) to measure the impact of economic factors in participating countries. Trends were compared by regression analyses, and countries were grouped by World Bank definitions into high, middle and low income categories.

Results Transplant rates increased over time with nearly linear trends, in clear association with GNI per capita (R2=0.72), and distinct by World Bank category within a narrow window of variation for both autologous HSCT (R2=0.95, 0.98 and 0.94 for high, middle and low income categories, respectively) and allogeneic HSCT (R2=0.99, 0.96 and 0.95 for high, middle and low income categories, respectively) when breast cancer (autologous) and chronic myeloid leukemia (allogeneic) were excluded. Team density (R2=0.72) and team distribution (R2=0.51) were also associated with transplant rates.

Interpretation and Conclusions Transplant rates for HSCT in Europe are highly predictable. They are primarily influenced by GNI per capita. The absence of saturation and a nearly linear trend indicate that infrastructure lags behind medical needs. Isolated changes in single disease entities can easily be recognized.

Hematopoietic stem cell transplantation (HSCT) is considered the treatment of choice for many patients with severe malignant or non-malignant, acquired or congenital disorders of the hematopoietic system or with chemosensitive, radiosensitive or immunosensitive tumors. HSCT has evolved over the last decades from an experimental procedure to the standard of care and is integrated into the treatment algorithm for many disease categories from diagnosis.1-4 Better supportive care, increased donor pools and novel conditioning regimens have extended its use to new categories of patients and disease indications. However, HSCT is a high-cost procedure and can present a financial challenge for patients and health care systems in any country.5-7 A correlation between the economic strength of individual countries and transplant rates, i.e. the number of transplants per number of inhabitants, was reported earlier by the European Group for Blood and Marrow Transplantation (EBMT).8, 9 This correlation explained some of the differences in numbers of transplants between Eastern and Western European countries. Transplant rates were higher in countries with higher Gross National Income (GNI) or higher health care expenditures (HCE) per capita.

It is easy to understand that health care providers would like to have information on future needs. HSCT is a complex procedure, and is dependent on the availability of a specific infrastructure, trained medical personnel and support staff. Providing the infrastructure and its mandatory quality management requirements takes time and, therefore, at least short-term predictions are warranted.10 This issue became first apparent with the sudden increase of autologous HSCT for breast cancer in the 1990s.11, 12 There was a massive increase of such transplants within a few years from nearly none to more than 5000 in Europe alone in 1996, followed by a similarly rapid decline. A similar phenomenon was observed a few years later with an increase and then rapid decrease in allogeneic HSCT for chronic myeloid leukemia in the late 1990s and the first few years of the new century. In 1999, chronic myeloid leukemia was the most frequent indication for an allogeneic HSCT worldwide. When imatinib mesylate, a specific inhibitor of the BCR/ABL tyrosine kinase, was introduced, transplant rates for chronic myeloid leukemia dropped and are still continuing to do so.13-15 These two observations created the feeling amongst hospitals and health care institutions that transplant rates were erratic, rapidly changing and unpredictable. A fear of having too much infrastructure became prevalent.

Making use of its annual activity surveys, the EBMT made an attempt to gain insight into the mechanisms of the evolution in HSCT. Based on the data from 1990 to 2000, short-term predictions were attempted and extrapolations made in 2000 for the transplant rates in 2003.16 These predictions were tested for their validity with the 2003 final data and extended throughout the observation period of the activity survey. The results of this analysis confirm the accuracy of the predictions made in 2000. They show that the changing usage of HSCT for breast cancer and chronic myeloid leukemia are the exception. As a rule, and adjusted for economic factors, transplant rates are highly predictable, increasing over time with nearly linear trends and in association with national income. There is no indication of saturation and the need for more infrastructure remains as urgent as before.