UNDERUTILIZATION PER YEAR:  44,740 – 4,056 = 40,684  or   10,171 PER YEAR (Data based on NMDP facilitated transplants)

The method used to derive the above data is as follows: The estimate of the number of patients in need of unrelated donor transplants was derived by using data on the number of HLA-identical sibling transplants obtained from IBMTR. For every HLA-identical sibling transplant recorded for a Caucasian patient, there will be 0.796134/(1 - 0.796134) = 3.90518 patients in need of unrelated donor transplants. (This number was derived for Caucasian patients from the average number of children born to Caucasian women over a lifetime.) Because there were 7,920 sibling transplants performed for Caucasian patients from 1997 through 2000, the estimate is that 3.90518(7,920) = 30,929 Caucasian patients were in need of stem cell transplants during that period. This figure and estimates for other racial and ethnic groups are presented in Table 1. Because minorities generally have less access to health care may therefore have less access to sibling transplants specifically, these estimates were obtained by assuming that each minority group's need for unrelated donor transplants is proportional to the Caucasian group's need. The estimates were obtained by multiplying the number of persons in the minority group by the proportion of Caucasians in need of unrelated donor transplants. This approach implicitly assumes that differences across groups in fertility rates are of negligible importance in computing the numbers of patients.

(Two other methods were used in the GAO Report to calculate the underutilization of hematopoietic cell transplants and they both yielded very similar conclusions. See the original report for details.)

A number of articles have sought the reasons for not receiving a hematopoietic cell transplant. In the study of Heemskerk et al. (Bone Marrow Transplant. 2005;35:645-52.) the two main causes that led to failure to reach transplantation were: (1) either no acceptable donor was available, or (2) the patients' clinical condition deteriorated. Kollman et al. (Bone Marrow Transplant 2001; 27:581-587) concluded that the most common cited barriers to transplantation were the death of the patient, worsening of the patient's medical condition and the length of the search process.

Thus, part of the reason that there are many patients (~10,000/year in the United States) who have an indication for a hematopoietic cell transplant but who are not transplanted is that an appropriate donor stem cell product is not found among family members and cannot be obtained expeditiously from registries of adult donors. Cord bloods are an important addition to the options available to transplant physicians since one can obtain a cord blood unit for a significant proportion of patients who do not have an HLA-matched family member, and the unit can be obtained more quickly than through registries of adult donors.

The above discussion is not meant to imply that the inability to obtain a stem cell product expeditiously is the only reason patients do not receive a transplant when one is indicated. Nevertheless, greater use of cord blood units for transplantation would allow for more transplants to occur. The transplant community should be dedicated to providing hematopoietic cell transplants whenever they are indicated.

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