2.1 Characteristic of HBeAg (+) and HBeAg (−) patients
We enrolled 1020 patients in this study from January 2011 to December 2013, including 881 males and 139 females; 252 patients were HBeAg-positive (HBeAg (+)) and 768 were HBeAg-negative (HBeAg (−)); 535 had high HBV DNA levels and 585 had low HBV DNA levels. The characteristics of the patients was shown in table 1. The values of age, the platelet count (PLT), aspartate aminotransferase (AST), and high HBV DNA levels are significant between the patients of HBeAg(+) and HBeAg(-) . The HBeAg(+) patients was younger, lower PLT levels, and higher AST levels than the HBeAg(-) patients. In contrast, the white blood cell (WBC) count and the levels of hemoglobin (HGB), total bilirubin (TB), alanine aminotransferase (ALT), albumin (ALB), and prothrombin time did not differ significantly. From figure 1-A, judging the high HBV DNA levels based on HBeAg(+) might be reliable, for the AUC (area of under the curve) was 0.622.
2.2 Characteristic in different HBV DNA levels
Table 1 shows the feature of high HBV DNA levels and low HBV DNA levels. The difference of PLT, AST, ALT, and ALB were significant between the high HBV DNA group and the low HBV DNA group, and the ROC was shown in figure 1-B. The AUC of AST, ALT, ALB, and PLT was 0.635, 0.642, 0.432, and 0.473, respectively, and the optimal cutoff points were 46.5 IU/L, 42.5 IU/L, 25.5 g/L, and 74.5 × 109/L, respectively. The levels of AST and ALT were higher in high HBV DNA group, and the levels of PLT and ALB were lower. Furthermore, the logistic regression multivariate analyses showed no significance in the PLT and AST. Through the logistic regression multivariate analysis and univariate analysis, the independent factors are ALT, ALB and HBeAg (table 3). We drew the following predictive model of high HBV DNA levels as:
Y1 (high HBV DNA levels) = 1.412 × (1 for HBeAg-positive >16.15 S/CO or 0 for others) + 0.004 × (1 for ALT > 42.5 U/L or 0 for others) −0.029 × (1 for ALB > 25.5 g/L or 0 for others) + 0.779
The ROC of the predictive model Y1 is shown in figure 2-A. The AUC is 0.606, and the cutoff value is 0.752.
2.3 The different HBV DNA levels in HBeAg (+) patients
The comparison of the HBeAg(+) patients with high and low HBV DNA levels were shown in table 2. The sex, age, PLT, WBC, TB, AST, and ALT were not significantly different. The variables of HGB, ALT, and HBeAg were significant in the univariate and multivariate analyses, and the AUC was 0.394, 0.379, and 0.787, respectively, with the optimal cut-off points being 170.5 g/L, 25.0 g/L, and 16.15 S/CO, respectively, (Figure 1-C).
2.4 The different HBV DNA levels in HBeAg (-) patients
Table 2 summarizes the HBV DNA levels characteristics of CHB in HBeAg(-) patients. The variables of TB, AST, and ALT were significantly different between the two groups as per univariate analysis. The AUC of these three variables was 0.511, 0.628, and 0.655, respectively (figure 1-D), and the cutoff values were 11.15 umol/L, 36.5 U/L, and 42.5 U/L, respectively. However, in the logistic regression multivariate analyzes, only TB and ALT were significant, as showing in table 3. Following the result, we can draw another predictive model of HBV DNA levels in the HBeAg(-) patients:
Y2 (low levels of HBV DNA) = 0.385 − 0.005 × (1 for ALT > 36.5 IU/L or 0 for others) − 0.006 × (1 for TB > 11.15 umol/L or 0 for others)
The ROC of the predictive model Y2 is shown in figure 2-B. The AUC was 0.609, and the cutoff value was 0.3765.