Patient demographic and laboratory variables
Among the 157 patients who were enrolled, 92 (58.6%) patients were male, the median age was 3.0 years old (IQR, 1.9, 4.1), and the median BMI was 16.01 (15.00, 17.28) (Table 1). Moreover, the laboratory variables, including the WBC count (8.2 ± 2.1, 109/L), PLT count [287 (236, 344), 109/L], alanine aminotransferase (ALT) [73 (42, 145), IU/L], AST [79 (55, 136), IU/L], Log10 HBV DNA quantification [7.87 (7.00, 8.01), IU/mL], and serological HBV markers are summarized in Table 1.
Noninvasive assessment indices for liver fibrosis and patient histological features
Next, noninvasive assessment indices were analyzed. As shown in Table 1, the LSM was 5.2 (4.4 - 6.1) kPa, ranging from 1.1 kPa to 12.6 kPa, APRI was 0.6778 (0.4573, 1.1296), and FIB-4 was 0.0951 (0.0639, 0.1434). In addition, 59 patients presented with mild or lack of necroinflammatory activity (A < 2), 96 patients were A2, and 2 patients were A3. There were 111 patients who exhibited a lack of or mild liver fibrosis (F0-F1), 30 individuals presented as F2, and 16 patients showed advanced fibrosis (F ≥ 3) (Table 1).
Correlation between LSM, APRI or FIB-4 and histological features in children with CHB
The activity grades in our study were divided into two groups: A < 2 and A ≥ 2, and the liver fibrosis stages were classified into three groups: F0-F1, F2, and F3-F4 in accordance with previous studies . The distribution of LSM, APRI, and FIB-4 according to activity grade and stages of liver fibrosis are displayed in Figure 1. A comparative analysis showed that the A ≥ 2 group [5.5 (4.6 - 6.5) kPa] had a higher median LSM value than that of the A < 2 group [4.8 (4.1 - 5.4) kPa] (P < 0.001) (Fig. 1a). Patients classified as F3-F4 stage had a significantly higher LSM compared to F0-F1 stage (8.3 vs 4.9 kPa; P < 0.001) and F2 stage (8.3 vs 5.6 kPa; P < 0.001) patients, whereas there was no significant difference in LSM values between patients in the F0-F1 stage and F2 stage groups (Fig. 1b). With regards to APRI, the A ≥ 2 group had higher values compared to the A < 2 group (0.9726 vs 0.4664, p < 0.001), whereas only the F3-F4 stage had significantly higher values than those of F0-F1 stage (1.4040 vs 0.5662, p < 0.05) (Fig. 1c and d). In addition, the FIB-4 levels were higher in the A ≥ 2 group compared with those in the A < 2 group (0.1104 vs 0.0814, p < 0.01); however, there was no significant differences in the fibrosis stages among the three groups (F0-F1, 0.0896, F2, 0.1321 and F3-F4, 0.1337, all p > 0.05) (Fig. 1e and f). We next estimated the correlation between LSM, APRI or FIB-4, and activity grades (A < 2 and A ≥ 2) or liver fibrosis stages (F0-F1, F2, and F ≥ 3). The results revealed that LSM (r = 0.275, P < 0.001), APRI (r = 0.478, P < 0.001), and FIB-4 (r = 0.249, P< 0 .01) were positively correlated with the degree of activity. We also found the three parameters were positively correlated with the fibrosis degree (LSM, r = 0.414, P < 0.001; APRI, r = 0.357, P < 0.001 and FIB-4, r = 0.277, P < 0.001). Overall, these data suggest that LSM, APRI and FIB-4 are positively associated with the severity of liver inflammation and fibrosis in CHB children.
Performance of LSM, APRI, and FIB-4 for liver fibrosis stages
To further evaluate the performance of LSM, APRI, and FIB-4 for the liver fibrosis stages, an ROC curve analysis was performed for all patients. The AUCs of LSM identifying fibrosis stages F ≥ 2 and F ≥ 3 among children with CHB were 0.732 (95% confidence interval, 0.639 - 0.826) and 0.941 (0.897 - 0.985), respectively (Table 2). The optimal cut-off values were 5.6 kPa and 6.9 kPa, specificity (%) values were 75.7 (66.6 - 83.3) and 91.5 (85.6 - 95.5), and sensitivity (%) values were 67.4 (52.0 - 80.5) and 81.3 (54.4 - 96.0) for F ≥ 2 and F ≥ 3, respectively (Table 2 and Fig. 2a and b). Additionally, compared to LSM, although the specificities of APRI predicting F ≥ 2 and F ≥ 3 were moderately higher, both the AUCs and sensitivities of APRI and FIB-4 for F ≥ 2 and F ≥ 3 were lower, especially for F ≥ 3 (Table 2 and Fig. 2a and b). Overall, these data suggest that LSM is reliable for assessing advanced liver fibrosis, which is superior to that of APRI and FIB-4, whereas all of these parameters were suboptimal for identifying significant liver fibrosis.
Independent parameters associated with the fibrosis stage F ≥ 2 according to the liver biopsy
We next performed a univariate analysis of the parameters associated with fibrosis stages of the liver biopsies (Table S1). We observed that ALT, AST, gamma-glutamyl transpeptidase (γ-GT), cholinesterase, PLT, HBeAg, and HBsAg quantification, Log10HBsAg, Log10HBV DNA, A ≥ 2, and LSM were significantly associated with the fibrosis stage (F ≥ 2) of the liver biopsy (all p < 0.05) (Table S3). Based on these results, further multivariate analyses showed that LSM, PLT, and Log10HBsAg were independent factors associated with the fibrosis stages of the liver biopsy (all p < 0.05) (Table 3).
Combination of LSM, PLT and Log10HBsAg to determine liver fibrosis stage F ≥ 2
Since LSM was associated with a relatively poor diagnostic accuracy for F ≥ 2 as shown in Table 2 and Fig. 2, LSM, PLT, and Log10HBsAg were further combined as independent factors associated with fibrosis stages to create an algorithm that could predict the presence of F ≥ 2 in our patients. This algorithm was the LPS index (LSM, PLT and Log10HBsAg) = 0.511 × LSM - 0.006 × PLT - 0.682 × Log10HBsAg + 0.769. The data revealed that the AUC increased to 0.792 (0.720 - 0.852), which was higher than that of LSM (0.792 vs 0.732, p < 0.05) (Table 4 and Fig. S1). More importantly, the sensitivity increased by almost 10 percent (76.7% vs 67.4%) (Table 5 and Fig. S1). Taken together, these findings demonstrate that compared to LSM, the combination of LSM, PLT, and Log10HBsAg could better predict liver fibrosis of F ≥ 2 with a higher AUC and greater sensitivity.