Design and Validation of an Augmented Hematopoietic Cell Transplantation-Comorbidity Index Comprising Pretransplant Ferritin, Albumin, and Platelet Count for Prediction of Outcomes after Allogeneic Transplantation

Pretransplant values of serum ferritin, albumin, and peripheral blood counts were previously suggested to provide prognostic information about hematopoietic cell transplantation (HCT) outcomes. Whether these "biomarkers" have prognostic value independent of each other and the HCT-comorbidity index (HCT-CI) is unknown. We analyzed data from 3917 allogeneic HCT recipients at multiple sites in the United States and Italy using multivariate models including each biomarker and the HCT-CI. Data from all sites were then randomly divided into a training set (n= 2352) to develop weights for the relevant biomarkers to be added to the HCT-CI scores and a validation set (n= 1407) to validate an augmented HCT-CI compared with the original index. Multivariate analysis with data from one site showed that ferritin, albumin, and platelets-not neutrophils or hemoglobin-were independently associated with increased nonrelapse mortality (NRM) and decreased overall survival. Findings were validated in data from the other sites. Subsequently, in a training set from all sites, ferritin >2500 mg/dL (hazard ratio [HR], 1.69); albumin 3 to 3.5 g/dL (HR, 1.61) and <3.0 g/dL (HR, 2.27); and platelets 50 to <100,000 (HR, 1.28), 20 to <50,000 (HR, 1.29), and <20,000 (HR, 1.55) were statistically significantly associated with NRM. Weights were assigned to these laboratory values following the same equation used to design the original index. In the validation set, the addition of the biomarkers to the original index to develop an augmented HCT-CI resulted in a statistically significant increase in a higher c-statisticestimate for prediction of NRM (P=.0007). Ferritin, albumin, and platelet counts are important prognostic markers that further refine the discriminative power of the HCT-CI for transplant outcomes.