Cost analysis of treatments for severe combined immunodeficiency patients caused by adenosine deaminase deficiency: comparison of gene therapy and bone marrow transplantation.

In order to perform a cost assessment of treatment for severe combined-immunodeficiency patients caused by adenosine deaminase deficiency, we estimated the cost for 3 successfully treated patients in Japan for whom related HLA-identical bone marrow donors could not be found. One patient received gene therapy and the other 2 patients received HLA-haploidentical bone marrow transplantation. The medical costs required for hospitalization periods for gene therapy and bone marrow transplantation were estimated respectively by analyzing the monthly bills that were calculated based on the fee schedule covered by health insurance. In the gene therapy, the total cost was calculated by adding the charges not covered by health insurance. The gene therapy and transplantation patients had significant differences in terms of cost structure and total cost. The items concerning "procedures" associated with gene transduction in the former amounted to 47.8% of the total cost, and "medication" in the latter amounted to 34.3% and 31.9% respectively. The items concerning "hospitalization" amounted to a large percentage in both treatments. The total cost was estimated at approximately 18.9 million yen for gene therapy, and 7.4 million yen and 10.5 million yen for transplantation. These results obtained through this study revealed the cost structure of gene therapy in comparison with transplantation. This report represents the first step to the assessment of medical technology of human gene therapy, in terms of medical cost, in which a stable and favorable therapeutic outcome was achieved.