Baseline characteristics.
Twenty-five patients were excluded: six had no baseline data, six missed follow-up before week 12, seven discontinued therapy during weeks 4–12 due to adverse events (three patients had symptoms of a severe flu, three had severe bone marrow suppression, and one had thyroid function abnormalities), five were examined by the Roche method, and one was excluded due to suspected data collection (Additional File 1: Figure S1). A total of 242 patients were enrolled in the final analysis. Among them, 78 patients (32.2%) achieved HBsAg loss at the EOF, of whom 76 had serological conversion.
Responders were younger (34 vs. 38; P = 0.002) and had lower HBsAg (1.75 vs. 2.81; P < 0.001) and lower ALT (0.95 vs. 1.25; P = 0.013) at baseline than non-responders. There were no statistically significant differences in sex, HBV DNA, anti-HBc, treatment (initial vs. experienced treatment), and treatment protocol (PEG-IFNα monotherapy vs. combination therapy) and duration (all, P > 0.05) between the response and no-response groups (Table 1).
Table 1
Baseline characteristics of patients stratified by the loss of HBsAg at the follow-up endpoint.
Characteristic
|
Total(n = 242)
|
RS(n = 78)
|
NRS(n = 164)
|
P value
|
Male, n (%)
|
197(81.40)
|
63(80.77)
|
134(81.71)
|
0.861
|
Age (years)
|
37(31–45)
|
34(30–41)
|
38(32–46)
|
0.002
|
ALT (×ULN)
|
1.15(0.80–1.80)
|
0.95(0.75–1.56)
|
1.25(0.86–1.88)
|
0.013
|
HBsAg (lg IU/ml)
|
2.28(1.60–3.11)
|
1.75(0.84–2.23)
|
2.81(2.01–3.30)
|
P < 0.001
|
Anti-HBc (S/CO)
|
9.45(8.57–10.54)
|
9.19(8.39–10.09)
|
9.53(8.64–10.63)
|
0.051
|
HBV DNA (lg copies/ml)
|
2.70(2.70–3.44)
|
2.70(2.70–3.08)
|
2.70(2.70–3.59)
|
0.069
|
Treatment modality
|
|
|
|
|
Initial treatment (%)
|
152(62.81)
|
46(58.97)
|
106(64.63)
|
|
Experienced treatment (%)
|
90(37.19)
|
32(41.03)
|
58(35.37)
|
0.395
|
Monotherapy (%)
|
132(54.55)
|
44(56.41)
|
88(53.66)
|
|
Combination (%)
|
110(45.45)
|
34(43.59)
|
76(46.34)
|
0.688
|
Duration (months)
|
12.0 (6.0–12.0)
|
12.0 (6.0–12.0)
|
12.0 (8.0–14.0)
|
0.067
|
Data are expressed as number (%), mean ± standard deviation, or median (interquartile range). ALT, alanine aminotransferase; HBsAg, hepatitis B surface antigen; anti-HBc, antibody to hepatitis B core antigen HBV, NRS, non-responders; RS, responders; ULN, upper limit of normal. |
Treatment and follow-up
ALT levels significantly increased in the response group at the beginning of treatment and peaked at 12 weeks, while no change was observed in the no-response group, posing a very significant difference (P < 0.01) (Fig. 1A). Serum HBV DNA notably declined at 12 weeks, at which most patients became negative in both groups. However, part of the no-response group became positive at EOF, resulting in significant differences between the two groups (P < 0.05) (Fig. 1B). HBsAg levels in the response group significantly and steadily decreased after treatment. However, HBsAg levels decreased only in the first 24 weeks, with an amplitude of < 1 Ig IU/mL, in the no-response group (all, P < 0.001) (Fig. 1C). Anti-HBc levels were relatively lower in responders during treatment and follow-up than in no-nresponders (all, P > 0.05) (Fig. 1D).
Performance of HBsAg in predicting response
HBsAg clearance was considered to indicate functional cure among patients with CHB. Therefore, baseline HBsAg was usually used as a predictor for treatment selection and prognosis prediction based on previous studies. Based on HBsAg distribution at baseline, and week 12 and 24, the response group had lower HBsAg levels than those of the no-response group (P < 0.001). It could still be found that patients with lower HBsAg levels failed to achieve functional cure, whereas those with higher HBsAg levels succeeded (Fig. 2A). HBsAg levels were classified into subgroups based on the following intervals: <100 IU/mL, 100–500 IU/mL, 500–1000 IU/mL, or > 1000 IU/mL at baseline, week 12, and 24. They were subsequently analyzed for response at EOF prediction. At baseline, the response rates for the different subgroups were 57.1%, 29.4%, 10.7%, and 11.1%, respectively. PEG-IFNα therapy was recommended to be administered weekly in patients with HBsAg > 100 IU/mL. Further, HBsAg clearance had little differences among those with HBsAg > 500 IU/mL. At week 12, 53 (21.9%) patients with HBsAg > 1000 IU/mL were able to stop PEG-IFNα treatment because of low response rates (1.9%), and at week 24, the response rates were 46.3%, 7.7%, and 0% for the HBsAg < 100 IU/mL, 100–500 IU/mL, and > 500 IU/mL groups, respectively (Fig. 2B).
Performance of multiple parameters in predicting response
Clinically meaningful cutoff values were used to classify the parameters, and the best predictors of treatment outcomes were assessed through univariate and multivariate logistic regression analyses. The three best baseline predictors of response were age ≤ 40 years, ALT level ≤ 40 U/L, and HBsAg level ≤ 100 IU/mL (Additional File 2: Table S1). The differences in HBsAg seroclearance between groups were statistically significant (37.3% vs. 23.1; 40.6% vs. 26.2; and 57.1% vs. 17.2; all, P < 0.05); the values of relative risk (RR) were 1.61, 1.55, and 3.32, respectively. Furthermore, some patients with HBsAg loss were from the group with predicted poor curative effect (above cut-off values), with the response rates being 26.9%, 47.4%, and 33.3%, respectively (Fig. 3A).
At week 12, the three most meaningful predictors of response were an ALT level ≥ 80 U/L, HBsAg level ≤ 50 IU/mL, and anti-HBc level ≤ 8.42 S/CO (Table S1). These three variables were grouped according to clinically meaningful cut-off values, and the difference in HBsAg seroclearance was statistically significant (41.6% vs. 24.0%; 56.2% vs. 9.9%; and 40.0% vs. 25.8%; all, P < 0.05); the values of RR were 1.73, 5.68, and 1.55, respectively. Furthermore, 12.8–39.7% of patients with HBsAg loss were from the group with predicted poor curative effect (Fig. 3B).
At week 24, the three most significant predictors of response were an ALT level ≥ 40 U/L (P < 0.006), HBsAg level ≤ 0.2 IU/ml (P < 0.001), and anti-HBc level ≤ 8.46 S/CO (P = 0.010) (Additional File 1: Table S1). These three variables were grouped according to clinically meaningful cut-off values, and the difference in HBsAg seroclearance between groups was statistically significant (37.0% vs. 18.0%, 93.4% vs. 11.6%, and 44.3% vs. 27.3%; all, P < 0.05); the values of RR were 2.06, 8.05 and 1.62, respectively. Furthermore, 14.1–60.3% of patients with HBsAg loss were from the group with predicted poor curative effect. The predictive value of anti-HBc was the lowest (Fig. 3C).
Multi-parameter score model in predicting response
The corresponding integrals were endowed according to the various odds ratio (OR) values of predictor variables. A score of 1 was given if patients had a change in each of the selected predictive parameters, and a score of 3 was given if the OR value of the factor studied was more than two times higher than that of the remaining values. Accordingly, the best three predictors of response at baseline were found to be age ≤ 40 years, an ALT level ≤ 40 U/L, and an HBsAg level ≤ 100 IU/mL; the OR values were 2.08, 2.28, and 7.89, respectively (Additional File 2: Table S1). They were respectively integrated with 1, 1, and 3 points when the three parameters reached the optimal threshold (Table 2). The response rates of patients with scores ranging from 0–5 were 17.6%, 11.7%, 27.5%, 21.4%, 59.2%, and 71.4%, respectively. The HBsAg loss rates of the group that scored 2 (27.5%) were even higher than that of the group that scored 3 (21.4%), suggesting that, although the single predictive value of age or ALT levels was inferior to that of HBsAg levels in terms of individual factors, combining these two factors significantly enhanced the prediction’s efficiency (Additional File 3: Figure S2 A). The scores were combined for the convenience of clinical application. For patients with scores of 0–1, 2–3, and 4–5, the response rates were 13.5% (15/111), 25.9% (14/54), and 63.6% (49/77), respectively (Fig. 4A).
Table 2
The factors most related to the loss rate of HBsAg and their corresponding scoring values.
|
Factors
|
Score
|
Baseline
|
Age ≤ 40 yr
|
1
|
|
ALT ≤ 40 U/L
|
1
|
|
HBsAg ≤ 100 IU/mL
|
3
|
12W
|
ALT ≥ 80 U/L
|
1
|
|
anti-HBc ≤ 9.42 S/CO
|
1
|
|
HBsAg ≤ 50 IU/mL
|
3
|
24W
|
ALT ≥ 40 U/L
|
1
|
|
anti-HBc ≤ 8.46 S/CO
|
1
|
|
HBsAg ≤ 0.2 IU/mL
|
3
|
ALT, Alanine aminotransferase; HBsAg, hepatitis B s antigen; anti-HBc, antibody to hepatitis B core antigen; w., week. |
At week 12, the best three predictors of response were an ALT level ≥ 80 U/L, anti-HBc level ≤ 8.42 S/CO, and HBsAg level ≤ 50 IU/mL; the OR values were 2.17, 2.30, and 17.48, respectively (Additional File 2: Table S1). They were respectively integrated with 1, 1, and 3 points when the three parameters reached the optimal threshold (Table 2). The response rates of patients with scores of 0, 1, 2, 3, 4, and 5 were 3.6%, 14.3%, 9.7%, 33.3%, 57.1%, and 74.1%, respectively (Additional File 3: Figure S2 A). The scores were combined for the convenience of clinical application. For patients with scores of 0–1, 2–3, and 4–5, the response rates were 7.8% (7/90), 20.0% (11/55) and 61.9% (60/97), respectively (Fig. 4A).
At week 24, the best three predictors of response were an ALT level ≥ 40 U/L, anti-HBc level ≤ 8.46 S/CO, and HBsAg level ≤ 0.2 IU/mL; the OR values were 20.17, 3.69, and 501.66, respectively (Additional File 2: Table S1). They were respectively integrated with 1, 1, and 3 points when the three parameters reached the optimal threshold (Table 2). The response rates of patients with scores of 0, 1, 2, 3, 4, and 5 were 10.3%, 9.8%, 26.7%, 66.7% and 97.4%, respectively (Additional File 3: Figure S2 A). The scores were combined for the convenience of clinical application. For patients with scores of 0–1, 2–3, and 4–5, the response rates were 8.6% (13/152), 33.3% (12/36), and 98.1% (53/54), respectively (Fig. 4A).
Prediction and evaluation based on RGT strategy
Patients with low scores had a lower response rate at the different time points (Fig. 4A). However, the scores of the same patient may have significantly differed between various time points (Fig. 5). At week 12, 32 (28.8%) and 18 (16.2%) patients who scored 0–1 at baseline had improved scores of 2–3 and 4–5, respectively. Among the patients who scored 2–3 at baseline, 44.4% (24/54) had decreased scores of 1–2, and 35.2% (19/54) had improved scores of 4–5. Only 22.1% (17/77) of patients who scored 4–5 at baseline had a score change (Fig. 5A). Analysis of the interrater agreement showed a kappa value of 0.302 (P < 0.001) (Additional File 4 and 5: Table S2, S3).
At week 24, 17 (15.3%) and 9 (8.1%) patients who scored 0–1 at baseline had improved scores of 2–3 and 4–5, respectively. Among the patients who scored 2–3 at baseline, 79.6% (43/54) had decreased scores of 0–1 point, and 13.0% (7/54) had improved scores of 4–5 points. In total, 31.2% (24/77) and 19.5% (15/77) of patients who scored 4–5 at baseline had decreased scores of 0–1 and 2–3 points, respectively (Fig. 5B). Analysis of the interrater agreement showed a kappa value of 0.221 (P < 0.001) (Additional File 4 and 6: Table S2, S4).
At week 12, the total number of patients whose scores are 0–1, 2–3 and 4–5 was 90, 55 and 97, respectively. In total, 7.8% (7/90) of patients who scored 0–1 at week 12 had a score change at week 24. Of the patients who scored 2–3 at week 12, 63.6% (35/55) converted to 0–1 point, and 12.7% (7/55) converted to 4–5 points. At week 24, 35.1% (34/97) and 17.5% (17/97) of patients who scored 4–5 points at week 12 had scores of 0–1 and 2–3, respectively (Fig. 5C). Analysis of the interrater agreement showed a kappa value of 0.361 (P < 0.001) (Additional File 4 and 7: Table S2, S5).
The total score at week 12 was obtained by adding each patient's score from baseline to week 12, and the cumulative score range was 0–10 points. It was found that the efficacy significantly increased with the total score (Additional File 3: Figure S2 B). At week 12, patients with scores of 0–1 and/or cumulative score of 0–2 had effective rates of 5.4% and 7.3%, respectively; patients with scores of 2–3 and/or cumulative score of 3–4 had effective rates of 17.6% and 20.3%, respectively; patients with scores of 4–5 and/or cumulative score of 5–7 had effective rates of 43.8% and 58.6%, respectively. For patients with scores of 4–5 and/or cumulative score of 8–10, efficacy was 73.3% and 61.0%, respectively (Fig. 4B, C).
The total score at week 24 was obtained by adding each patient's score from baseline to week 24, and the cumulative score range was 0–15 points (Additional File 3: Figure S2 B). The effective rates of patients with scores of 0–1 and/or cumulative score of 0–3 total were 6.6% and 8.6%; patients with scores of 2–3 and/or cumulative score of 4–6 had effective rates of 7.1% and 19.1%, respectively; patients with scores of 2–3 and/or cumulative score of 7–10 had effective rates of 47.4% and 35.0%, respectively. For patients with scores of 4–5 and/or cumulative score of 11–15, efficacy was 96.4% and 96.4%, respectively (Fig. 4B, C).