Long-Term Survival after Blood and Marrow Transplantation: Comparison with an Age- and Gender-Matched Normative Population
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abstract
A plateau in long-term survival patterns of patients undergoing blood and marrow transplantation (BMT) from allogeneic donors is apparent, but whether their expected survival ever parallels that of the normative population is unclear. This study attempts to identify a cutoff time for classifying BMT patients as long-term survivors and compares their actual survival with the expected survival of an age- and gender-matched "normal" population. In this study, the records of 1386 patients who underwent allogeneic BMT at Princess Margaret Hospital between 1970 and 2002 were reviewed. Hazard rates (HRs), Kaplan-Meier survival estimates, and loss curves were used to propose a cutoff time classifying patients as long-term survivors. Factors predictive of overall survival and survival for long-term survivors were investigated. Actual survival for these patients was compared with the expected survival of the Canadian "normal" population. A cutoff time of 6 years post-BMT was proposed to define long-term survivors based on loss curves of hazard ratios and yearly survival statistics. The only statistically significant predictor of survival among long-term survivors was having a male donor (HR = 0.39; 95% confidence interval [CI] = 0.17-0.88). Although only 62% of patients survived the first year post-BMT, 98.5% of patients alive after 6 years survived at least another year. Almost 1/3 (31%) of the deaths in long-term survivors resulted from causes unrelated to transplantation or relapse. The observed number of deaths among BMT patients exceeded the expected number from the Canadian population; however, the difference in life expectancy decreased the longer that a patient survived. The 95% CIs for the observed/expected number of deaths cover 1, indicative of no difference, after the tenth year post-BMT. A cutoff of 6 years is proposed to define long-term survivorship after BMT. Life expectancy remained reduced compared with that of the "normal" population; however, this difference decreased the longer that a patient survived. Known risk factors of short-term survival disappeared, with only donor gender predictive of survival among long-term survivors.
