Development and validation of a comorbidity index for predicting survival outcomes after allogeneic stem cell transplantation in adult patients with acute leukemia: a Korean nationwide cohort study

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (alloSCT) is a potentially curative treatment option for acute leukemia. We aimed to identify the comorbidity factors affecting survival outcomes after alloSCT and develop a new comorbidity index tool for predicting overall survival (OS). METHODS: A Korean nationwide cohort of 3,809 adults with acute leukemia treated with alloSCT between January 2002 and December 2018 was analyzed as the development cohort. A retrospective cohort comprising 313 consecutive adults with acute leukemia who underwent alloSCT between January 2019 and April 2020 was analyzed as the validation cohort. RESULTS: In the development cohort, advanced age, male sex, and comorbidities such as previous non-hematologic malignancy, hypertension, and coronary or cerebral vascular disease were significantly related to poor OS. Subsequently, a new comorbidity scoring system was developed, and risk groups were created, which included the low-risk (score ≤0.17), intermediate-risk (0.17< score ≤0.4), high-risk (0.4< score ≤0.55), and very high-risk (score >0.55) groups. The 1-year OS rates were discriminatively estimated at 73.5%, 66.2%, 61.9%, and 50.9% in the low-risk, intermediate-risk, high-risk, and very high-risk groups in the development cohort, respectively (P<0.001). The developed scoring system yielded discriminatively different 1-year OS rates and 1-year incidence of non-relapse mortality according to the risk group (P=0.085 and P=0.018, respectively). Furthermore, the developed model showed an acceptable performance for predicting 1-year non-relapse mortality with an area under the curve of 0.715. CONCLUSION: The newly developed predictive scoring system could be a simple and reliable tool helping clinicians to assess risk of alloSCT in adults with acute leukemia.