Characteristics of the patients
Three liver transplantation centers provided retrospective data for 269 patients. Patients in our center were used as the training cohort (n = 233) and the patients in the remaining centers comprised the validation cohort (n = 36). There was a near 6:1 proportion of patients between two groups. The patients’ baseline characteristics are shown in Table 1.
Overall survival (OS)-related prognostic factors
Univariate and multivariate Cox regression analyses were used to assess the demographic, clinical, and biochemical parameters of the training cohort to identify independent risk factors associated with OS. The results revealed that OS was significantly associated with the presence of ascites, HbeAg positive, blood-type compatibility unmatched, liver transplantation criteria, and high model for end-stage liver disease (MELD) (Table 2). Upon multivariate analysis, HbeAg positive, blood-type compatibility unmatched, liver transplantation criteria, and a high MELD score were suggested as independent OS-related risk factors (Table 2).
OS-associated risk factors-based prognostic nomogram
The four identified independent risk factors for OS were used to construct a nomogram to predict the survival of patients with HCC after LT (Fig. 1). The odds ratio (OR) was used to weight the assignment of points to each factor. The total score was then used to calculate the survival probability at specific times (1, 2 and 3 years post-LT). For example, a patient with HCC after LT within the MC criteria (0 point), with a MELD score of 20 (50 points), HbeAg positive (26 points), and blood-type compatibility matched (0 points) would have a total score of 76 points, which corresponded to survival probabilities of 79%, 58%, and 51% at 1, 2, and 3 years, respectively.
Using the nomogram, the training cohort received a C-index for the prediction of OS of 0.677 (95% CI, 0.606–0.748; Fig. 2, upper panel), and the C-index was 0.874 for the validation cohort (95% CI, 0.753–0.995; Fig. 2, lower panel).
Three risk groups were identified using the risk scores calculated using the nomogram (Table 3): 1) The low-risk group (total points £ 79 and a predicted survival rate ³ 50%), with a mean predicted mean survival rate = 68.2%; 2) The intermediate-risk group (total points 79–107 and a predicted survival rate of 30–50%), with a mean predicted survival rate = 39.6%; and 3) the high-risk group (total points ³107 and a predicted survival rate £ 30%), with a mean predicted survival rate = 20.1%.
The observed survival rate conformed completely with the mean predicted survival rate. Among the risk groups there were significant differences in survival (P＜0.0001). Figure 3 shows the cumulative patient survival rates for the three groups. The low risk group had significantly better survival than the intermediate-risk group (P = 0.000). There was also a significant difference between the high-risk and intermediate-risk groups (P = 0.009).