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.