Figure 1. Study scheme of discovery and validation.

Clinical data and serum samples after hematopoietic stem cell transplantation were available from 114 patients transplanted at The First Affiliated Hospital of Soochow University. Serum samples were collected on days –9, 0, 7, and 14 after transplantation. We randomly selected 13 patients with 0–I aGVHD and 15 with II–IV aGVHD to set up a discovery set. The rest of the patients (59 with aGVHD 0–I and 27 with II–IV aGVHD) were included in the validation set. Our metabolic analyses always began with the discovery set. Significant metabolic changes were observed on day 7 (P < 0.001). The ratio of two metabolites (stearic acid/palmitic acid [SA/PA]) was considered as a single biomarker. Logistic regression, Cox regression, competing-risks regression, and leave-one-out cross-validation were used to evaluate the association of the potential metabolites with the occurrence of aGVHD, overall survival, progress-free survival, relapse, and mortality without relapse.