How can disease-free survival of adult ALL patients with or without transplants be compared?

525 patients with acute lymphoblastic leukemia (ALL) between the ages of 15 and 44 were treated according to the German study protocol. 41 patients received HLA-identical sibling bone marrow transplants in first remission. Disease-free survival was compared in patients with transplants and patients who were intended for further chemotherapy. After adjusting for potential biases, prognostic profiles of the two groups could be determined, the impact of time-to-transplant bias estimated and similar patients compared after appropriate adjustments. The initial patient characteristics of both groups were quite comparable as was the treatment outcome. The three year probability of disease-free survival was 34% (95% confidence interval: 16% to 52%) in both groups after statistical adjustment.