3.1 Patient characteristics
A total of 470 patient were enrolled, and the characteristics were all comparable between training and validation cohort (Table 1). All patients achieved neutrophil engraftment and the median time from HSCT to neutrophil engraftment was 12 days (range, 9–28) days. Four hundred and fifty-eight (97.4%) patients achieved platelet engraftment and the median time from HSCT to platelet engraftment was 13 days (range, 7–144) days, respectively.
Two hundred and sixty-six (56.6%), 129 (27.4%), and 33 (7.0%) patients experienced grade I to IV aGVHD, grade II to IV aGVHD, and grade III to IV aGVHD after allo-HSCT, respectively. The median time from HSCT to aGVHD was 20 days (range, 8–99) days. The cumulative incidence of grade I to IV aGVHD, grade II to IV aGVHD, and grade III to IV aGVHD at 100 days after HID HSCT was 56.5% (95%CI, 52.0%–61.0%), 27.3% (95%CI, 23.3%–31.3%), and 6.8% (95%CI, 4.5%–9.1%), respectively.
Thirty-eight (8.1%) patients experienced relapse, and 16 (3.4%) patients died of NRM. Four hundred and forty-nine patients survived until the last follow-up, and the median duration of follow-up was 200 days (range, 52 to 509) days. The probabilities of relapse, NRM, LFS, and OS at 100 days after HID HSCT were 2.8% (95%CI, 1.3%–4.3%), 1.5% (95%CI, 0.4%–2.6%), 95.7% (95%CI, 93.9%–97.6%), and 97.8% (95%CI, 96.5%–99.2%), respectively.
3.2 Predicted model for grade III to IV aGVHD (model 1)
A predictive model for grade III-IV aGVHD was developed (Supplementary methods, Table S1 and Fig. S1), and the equation was as follows:
Probability (grade III-IV aGVHD) =
where
Y= –0.0288 × (age) + 0.7965 × (gender) + 0.8371 × (CD3+ / CD14+ cells ratio in graft) + 0.5829 × (donor/recipient relation) – 0.0089 × (CD8+ cell counts in graft) – 2.9046. Particularly, donor/recipient relation included immediate relative donors other than MDs (value=0), MDs (value=1), and CRDs (value=2). Gender included male (value=0) and female (value=1). The age (years), CD8+ cell counts (×106/kg), CD3+/CD14+ cells ratio in graft used actual numerical value (Table S1). The threshold of probability was 0.057392 and the g-mean was 0.682. Patients were separated into low- and high-risk groups by the threshold.
In the training cohort, the sensitivity, specificity, area under curve score, and accuracy score were 0.632, 0.680, 0.685, and 0.678, respectively. ROC curve for the model and confusion matrix is shown in Fig. 2A and Table S2. In the validation cohort, the sensitivity, specificity, area under curve score, and accuracy score were 0.500, 0.760, 0.673, and 0.733, respectively. ROC curve for the model and confusion matrix is shown in Fig. 2B and Table S3.
3.3 Verifying the predicted model in validation and total cohort
The 100-day cumulative incidence of grade III-IV aGVHD in the low- and high-risk groups was 4.1% (95%CI, 1.9%–6.3%) versus 12.8% (95%CI, 7.4%–18.2%) (P = 0.001), respectively, in total cohort (Fig. 3A).
The 100-day cumulative incidence of grade III-IV aGVHD in the low- and high-risk groups was 3.2% (95%CI, 1.2%–5.1%) versus 10.6% (95%CI, 4.7%–16.5%) with P = 0.006 and 6.1% (95%CI, 1.3%–10.9%) versus 19.4% (95%CI, 6.3%–32.5%) with P = 0.017, respectively, in training cohort (Fig. 3B) and validation cohort (Fig. 3C).
The rates of grade III to IV skin and gut aGVHD in low-risk group were both significantly lower than those of high-risk group (skin: 4.4% vs. 12.8%, P = 0.001; gut: 1.6% vs. 4.7%, P = 0.045) (Fig. 3D).
3.4 Validation of the predicted model in grade II to IV aGVHD
In the total population, the 100-day cumulative incidence of grade II to IV aGVHD in the low-risk group and high-risk group was 21.5% (95%CI, 17.0%–26.0%) and 39.6% (95%CI, 31.7%–47.5%), respectively (P < 0.001, Fig. 4A). The rates of grade II to IV skin and gut aGVHD in the low-risk group were both significantly lower than those of high-risk group (skin: 25.5% vs. 35.6%, P = 0.025; gut: 7.5% vs. 18.8%, P < 0.001) (Fig. 4B).
3.5 Validation of the predicted model in grade I to IV aGVHD
In total population, the 100-day cumulative incidence of grade I to IV aGVHD in the low-risk group and high-risk group was 51.5% (95%CI, 46.0%–57.0%) and 67.1% (95%CI, 59.5%–74.7%), respectively (P = 0.001, Fig. 4C). The rates of grade I to IV skin, gut, and liver aGVHD in the low-risk group were all significantly lower than those of high-risk group (skin: 44.5% vs. 60.4%, P = 0.001; gut: 15.9% vs. 30.2%, P < 0.001; liver: 1.9% vs. 5.4%, P = 0.038) (Fig. 4D).
3.6. Validation of the predicted model in other clinical outcomes after HSCT
In total population, the probabilities of relapse, NRM, LFS, and OS at 100 days after HID HSCT were all comparable between the low- and high-risk groups in the total population (Fig. S2A-D).