COMPARISON OF CHEMOTHERAPY AND BONE-MARROW TRANSPLANTS USING 2 INDEPENDENT CLINICAL DATABASES

Comparing the outcome of chemotherapy and bone marrow transplants in t he absence of a randomized trial is difficult but necessary for diseas es where small numbers of patients make such trials difficult if not i mpossible. To address this issue for adults with acute lymphoblastic l eukemia in first remission, we created an empirical database using two separate datasets, one from the International Bone Marrow Transplant Registry and the other from two multicenter chemotherapy studies. Prio r to combining the datasets, a study protocol was developed to define inclusion criteria, outcomes to be compared and statistical methods. T he main problems of a non-randomized comparison are biases potentially introduced by differences in baseline composition of the two cohorts and differences in time-to-treatment. The source of the latter bias is different distributions of waiting times between achieving complete r emission and receiving post-remission therapy. Several techniques to c ontrol these biases were evaluated; each gave qualitatively similar re sults. These methods can easily be applied to other clinical situation s where randomized trials are not available.