Decreasing hepatitis B viral load is associated with a risk of significant liver fibrosis in hepatitis B e antigen positive chronic hepatitis B

Significant liver histological change is common in HBeAg-positive chronic hepatitis B with normal ALT

BACKGROUND AND AIMS

Numerous HBeAg-positive chronic hepatitis B (CHB) patients with persistently normal ALT have significant liver histopathology. It is imperative to identify true "immune tolerant" patients. We aimed to evaluate the liver histopathology features of HBeAg-positive CHB patients with normal ALT and the incidence of liver cirrhosis and HCC in CHB patients during follow-up.

METHODS

179 HBeAg-positive CHB patients with normal ALT who performed liver biopsy from 2009 to 2018 were retrospectively analyzed. Liver necroinflammation ≥ G2 and/or liver fibrosis ≥ S2 was defined as significant liver histopathological change.

RESULTS

57.5% patients were in the indeterminate phase with significant liver histological changes. The proportion of the patients with evident liver necroinflammation was higher in the high-normal ALT group (21-40U/L) when compared with the low-normal ALT group (≤ 20 U/L) (51.3% vs. 30.0%, p < 0.05), and patients aged ≥ 40 years had a higher proportion of significant fibrosis than those aged < 40 years (64.5% vs. 39.9%, p < 0.05). The percentages of patients with ≥ S2 and ≥ G2/S2 in the HBV DNA < 107 IU/mL group were higher than those in the HBV DNA ≥ 107 IU/mL group (72.7% vs. 40.1%, p < 0.01; 81.8% vs. 54.1%, p < 0.05). During follow-up, two of immune tolerant patients and four of indeterminate patients developed into cirrhosis, and one of immune tolerant patients and one of indeterminate patients developed into HCC, respectively.

CONCLUSIONS

HBeAg-positive CHB patients with high-normal ALT or HBV DNA < 107 IU/mL were tend to be indeterminate. Liver biopsy or noninvasive approaches are recommended to evaluate liver histopathology, and antiviral therapy is recommended for patients with significant liver histopathology.

Lower HBV DNA level is associated with more severe liver fibrosis in HBeAg-positive chronic hepatitis B with normal alanine transaminase

BACKGROUND

The association of hepatitis B virus (HBV) DNA levels and liver fibrosis in chronic hepatitis B (CHB) patients with immune-tolerant phase remains unclear. We explored the association between liver fibrosis and HBV DNA levels in HBeAg-positive CHB patients with normal alanine transaminase (ALT) with relatively high HBV DNA.

METHODS

Six hundred and twenty-two HBeAg-positive CHB patients with normal ALT were included. Patients were divided into three categories: low (6 log10 IU/mL ≤ HBV DNA < 7 log10 IU/mL), moderate (7 log10 IU/mL ≤ HBV DNA < 8 log10 IU/mL), and high (HBV DNA ≥ 8 log10 IU/mL). APRI, FIB-4, transient elastography, or liver biopsy were used to assess liver fibrosis.

RESULTS

The median age of patients was 33.0 years and 57.9% patients were male. 18.8%, 52.1%, and 29.1% of patients had low, moderate, and high HBV DNA levels, respectively. The APRI (0.33 vs. 0.26 vs. 0.26, P < 0.001), FIB-4 (1.03 vs. 0.71 vs. 0.68, P < 0.001), and LSM values (7.6 kPa vs. 5.6 kPa vs. 5.5 kPa, P = 0.086) were higher in low HBV DNA group than other two groups. Low HBV DNA group had higher proportions of significant fibrosis (24.8% vs. 9.9% vs. 3.3%, P < 0.001) and cirrhosis (7.7% vs. 2.5% vs. 1.1%, P = 0.004) than moderate and high HBV DNA groups. Moderate (OR 3.095, P = 0.023) and low (OR 4.968, P = 0.003) HBV DNA were independent risk factors of significant fibrosis.

CONCLUSION

Lower HBV DNA level was associated with more severe liver fibrosis in HBeAg-positive CHB patients with ALT.

Patients with chronic hepatitis B who have persistently normal alanine aminotransferase or aged < 30 years may exhibit significant histologic damage

BACKGROUND

The timing of antiviral therapy for chronic hepatitis B (CHB) patients with normal alanine transaminase (ALT) or aged < 30 years is still undetermined. We aimed to elucidate the correlation between liver histology, age, and ALT level in CHB patients and analyze the histological characteristics of the liver among patients with persistently normal ALT or aged < 30 years.

METHODS

A retrospective analysis was conducted on 697 treatment-naive CHB patients. Liver biopsies were performed, and significant histological damage was defined as the grade of liver inflammation ≥ G2 and/or fibrosis ≥ S2 based on the Scheuer scoring system.

RESULTS

The liver inflammation grades and fibrosis stages correlated positively with age, ALT, AST, GGT levels and negatively with the counts of PLT (all p < 0.050) in HBeAg-positive patients. Higher ALT levels and lower PLT counts were independently associated with significant liver inflammation and fibrosis in both HBeAg-positive and HBeAg-negative patients. Furthermore, among those with persistently normal ALT levels, the incidence of significant liver inflammation and fibrosis were 66.1% and 53.7% in HBeAg-positive groups, and 63.0% and 55.5% in HBeAg-negative groups. Moreover, there was no significant difference in the prevalence of significant liver damage between patients aged < 30 years and those aged ≥ 30 years, in both HBeAg-positive (≥ G2 or ≥ S2: 63.8% vs. 75.8%, p = 0.276) and HBeAg-negative (≥ G2 or ≥ S2: 65.9% vs. 72.5%, p = 0.504) groups, among patients with persistently normal ALT levels.

CONCLUSIONS

A considerable proportion of CHB patients with persistently normal ALT, including those below the age of 30 years, exhibited significant histological damage. This highlights the importance of initiating early antiviral therapy for HBV-infected individuals, even in the absence of elevated ALT levels.

Liver histopathological lesions is severe in patients with normal alanine transaminase and low to moderate hepatitis B virus DNA replication

BACKGROUND

Chronic hepatitis B virus (HBV) infection remains a major global public health problem. Chronic hepatitis B (CHB) patients can be divided into treatment indication and non-treatment indication individuals according to alanine transaminase (ALT), HBV DNA, serum hepatitis B e antigen status, disease status [liver cirrhosis, hepatocellular carcinoma (HCC), or liver failure], liver necroinflammation or fibrosis, patients' age, and family history of HCC or cirrhosis. For example, normal ALT patients in 'immune-tolerant' phase with HBV DNA higher than 107 or 2 × 107 IU/mL, and those in 'inactive-carrier' phase with HBV DNA lower than 2 × 103 IU/mL do not require antiviral therapy. However, is it reasonable to set the defined values of HBV DNA as the fundamental basis to estimate the disease state and to determine whether to start treatment? In fact, we should pay more attention to those who do not match the treatment indications (gray-zone patients both in the indeterminate phase and in the 'inactive-carrier' phase).

AIM

To analyze the correlation of HBV DNA level and liver histopathological severity, and to explore the significance of HBV DNA for CHB with normal ALT.

METHODS

From January 2017 to December 2021, a retrospective cross-sectional set of 1299 patients with chronic HBV infection (HBV DNA > 30 IU/mL) who underwent liver biopsy from four hospitals, including 634 with ALT less than 40 U/L. None of the patients had received anti-HBV treatment. The degrees of liver necroinflammatory activity and liver fibrosis were evaluated according to the Metavir system. On the basis of the HBV DNA level, patients were divided into two groups: Low/moderate replication group, HBV DNA ≤ 107 IU/mL [7.00 Log IU/mL, the European Association for the Study of the Liver (EASL) guidelines] or ≤ 2 × 107 IU/mL [7.30 Log IU/mL, the Chinese Medical Association (CMA) guidelines]; high replication group, HBV DNA > 107 IU/mL or > 2 × 107 IU/mL. Relevant factors (demographic characteristics, laboratory parameters and noninvasive models) for liver histopathological severity were analyzed by univariate analysis, logistics analysis and propensity score-matched analysis.

RESULTS

At entry, there were 21.45%, 24.29%, and 30.28% of the patients had liver histopathological severities with ≥ A2, ≥ F2, and ≥ A2 or/and ≥ F2, respectively. HBV DNA level (negative correlation) and noninvasive model liver fibrosis 5 value (positive correlation) were independent risk factors for liver histopathological severities (liver necroinflammation, liver fibrosis, and treatment indication). The AUROCs of the prediction probabilities (PRE_) of the models mentioned above (< A2 vs ≥ A2, < F2 vs ≥ F2, < A2 and < F2 vs ≥ A2 or/and ≥ F2) were 0.814 (95%CI: 0.770-0.859), 0.824 (95%CI: 0.785-0.863), and 0.799 (95%CI: 0.760-0.838), respectively. HBV DNA level (negative correlation) was still an independent risk factor when diagnostic models were excluded, the P values (< A2 vs ≥ A2, < F2 vs ≥ F2, < A2 and < F2 vs ≥ A2 or/and ≥ F2) were 0.011, 0.000, and 0.000, respectively. For the propensity score-matched pairs, whether based on EASL guidelines or CMA guidelines, the group with significant liver histology damage (≥ A2 or/and ≥ F2) showed much lower HBV DNA level than the group with non- significant liver histology damage (< A2 and < F2). Patients in the moderate replication group (with indeterminate phase) had the most serious liver disease pathologically and hematologically, followed by patients in the low replication group (with 'inactive-carrier' phase) and then the high replication group (with 'immune-tolerant' phase).

CONCLUSION

HBV DNA level is a negative risk factor for liver disease progression. The phase definition of CHB may be revised by whether the level of HBV DNA exceeds the detection low limit value. Patients who are in the indeterminate phase or 'inactive carriers' should receive antiviral therapy.

Identification of pseudo-immune tolerance for chronic hepatitis B patients: Development and validation of a non-invasive prediction model

Background and aims

Patients with chronic hepatitis B (CHB) in the immune tolerant (IT) phase were previously thought to have no or slight inflammation or fibrosis in the liver. In fact, some CHB patients with normal ALT levels still experience liver fibrosis. This study aimed to develop and validate a non-invasive model for identifying pseudo-immune tolerance (pseudo-IT) of CHB by predicting significant liver fibrosis.

Methods

This multi-center study enrolled a total of 445 IT-phase patients who had undergone liver biopsy for the training cohort (n = 289) and validation cohort (n = 156) during different time periods. A risk model (IT-3) for predicting significant liver fibrosis (Ishak score ≥ 3) was developed using high-risk factors which were identified using multivariate stepwise logistic regression. Next, an online dynamic nomogram was created for the clinical usage. The receiver operating characteristic (ROC) curve, net reclassification improvement and integrated discrimination improvement were used to assess the discrimination of the IT-3 model. Calibration curves were used to evaluate the models’ calibration. The clinical practicability of the model was evaluated using decision curve analysis and clinical impact curves.

Results

8.8% (39 of 445) patients presented with significant liver fibrosis in this study. Aspartate aminotransferase (AST), hepatitis B e-antigen (HBeAg), and platelet (PLT) were included in the prediction model (IT-3). The IT-3 model showed good calibration and discrimination both in the training and validation cohorts (AUC = 0.888 and 0.833, respectively). The continuous NRI and IDI showed that the IT-3 model had better predictive accuracy than GPR, APRI, and FIB-4 (p &lt; 0.001). Decision curve analysis and clinical impact curves were used to demonstrate the clinical usefulness. At a cut-off value of 106 points, the sensitivity and specificity were 91.7 and 70.2%, respectively.

Conclusion

The IT-3 model proved an accurate non-invasive method in identifying pseudo-IT of CHB, which can help to formulate more appropriate treatment strategies.

Significant histological disease of patients with chronic hepatitis B virus infection in the grey zone

BACKGROUND

Many patients with chronic hepatitis B (CHB) do not meet the definitions of the traditional natural phases and are classified as being in the grey zone (GZ).

AIMS

To investigate liver histology, and to establish a management strategy for patients with CHB in the GZ.

METHODS

This study included 1043 patients with CHB who underwent liver biopsy. Phases of natural history were determined according to the AASLD 2018 hepatitis B guidance. CHB patients in the GZ were divided into HBeAg-positive, normal ALT and HBV DNA ≤10⁶  IU/ml (GZ-A); HBeAg-positive, elevated ALT and HBV DNA ≤2 × 10⁴  IU/ml (GZ-B); HBeAg-negative, normal ALT and HBV DNA ≥2 × 10³  IU/ml (GZ-C) and HBeAg-negative, elevated ALT and HBV DNA ≤2 × 10³  IU/ml (GZ-D). Significant histological disease was defined as liver inflammation ≥G2 and/or liver fibrosis ≥S2.

RESULTS

Two hundred and forty two (23.2%) patients were in the GZ. Approximately 72.7% had significant histological disease. HBeAg-positive GZ CHB patients had a higher proportion of significant histological disease than HBeAg-negative GZ patients (91.1% vs. 68.5%, p = 0.002). GZ-D (42.6%) was the dominant category, followed by GZ-C (38.8%), GZ-A (10.3%) and GZ-B (8.3%). The highest proportion of significant histological disease was observed patients in GZ-B (100.0%), followed by GZ-A (84.0%), GZ-D (69.9%) and GZ-C (67.0%). Prothrombin time (PT) was an independent risk factor of significant histological disease in the HBeAg-negative GZ.

CONCLUSIONS

Over 70% of GZ CHB patients had significant histological disease. We recommend antiviral treatment for HBeAg-positive and HBeAg-negative GZ CHB patients with high PT.

The clinical value of serum hepatic parenchyma cell volume-normalized hepatitis B surface antigen levels in hepatitis B e antigen -positive and -negative chronic hepatitis B patients

BACKGROUND

While serum hepatitis B surface antigens (HBsAg) play an important role in the diagnosis and assessment of treatment results of hepatitis B virus (HBV) infections, it remains unclear whether HBsAg levels normalized to hepatic parenchymal cell volume (HPCV) is a superior indicator of disease state. This study compared the absolute and HPCV-normalized serum HBsAg levels in hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients with chronic hepatitis B (CHB).

METHODS

Patients admitted to our institution with CHB were retrospectively included and categorized into the HBeAg-positive and HBeAg-negative groups. HPCV was calculated based on pathological examination of liver biopsy specimens and theory of sphere geometry. The difference between HBsAg levels and HBsAg normalized to HPCV, and also correlation between HBsAg levels and liver inflammation and fibrosis was analyzed.

RESULTS

Absolute HBsAg levels (P=0.004), but not HPCV-normalized HBsAg levels (P=0.071) were significantly higher in HBeAg-positive patients compared to HBeAg-negative patients. In HBeAg-positive CHB patients, absolute HBsAg levels were positively correlated with liver inflammation grade (R=0.285, P=0.001) and hepatic fibrosis stage (R=0.351, P<0.001), as were HPCV-normalized HBsAg levels (R=0.640 and 0.742, both, P<0.001). However, in HBeAg-negative CHB patients, only HPCV-normalized HBsAg level were correlated with liver inflammation grade and hepatic fibrosis stage (R=0.640 and 0.785, both, P<0.001).

CONCLUSIONS

HPCV-normalized serum HBsAg levels, rather than absolute HBsAg levels, were positively correlated with liver inflammation grade and hepatic fibrosis stage in both HBeAg-positive and HBeAg-negative CHB patients. Thus, HPCV-normalized HBsAg levels may more accurately reflect the pathological progress of CHB patients compared to absolute HBsAg levels.

Are there optimal alanine aminotransferase and HBV DNA thresholds for discriminating HBeAg-positive chronic infection from chronic hepatitis? An evaluation of 215 young and male cases

OBJECTIVES

To define the importance of biochemical and virological thresholds for the prediction of significant liver diseases.

METHODS

A total of 215 young and male HBeAg-positive cases followed up in a tertiary training and research hospital in Turkey between 2008 and 2017 enrolled in the retrospective diagnostic accuracy study. Results: Fibrosis scores varied between 0-4, F1 (n=81, 37.6%) and F2 (n=82, 38.1%) were the most frequent fibrosis stages. Of the patients, 58.6% (126/215) had a significant histopathological abnormality (SHA). The ratio of SHA was higher for ALT greater than 90 U/L (n=68/95; 71.6%) and HBV-DNA between 2,000,000-200,000,000 IU/mL (n=47/73; 64.4%). Thresholds for the higher odds ratio (OR) for SHA were greater than 90 U/L for alanine aminotransferase (ALT) and greater than 2,000,000 IU/mL for HBV-DNA. Based on receiver operating characteristic analysis, 90.5 U/L of ALT and 22,607,500 IU/mL of HBV-DNA were levels with the optimum sensitivity and specificity for the prediction of SHA.

CONCLUSION

Hepatitis B virus-DNA levels between 106 and 108 IU/mL and ALT levels of 2~3 x ULN might be considered to be good indicators for discriminating chronic hepatitis phase from chronic infection in  hepatitis B e-antigen-positive chronic hepatitis. However, we think that the current biochemical, serological and molecular markers are inadequate for differentiating chronic hepatitis phase than chronic infection, and non-invasive test and/or liver histopathology should be carried out in selected cases.

The relationship between serum hepatitis B virus DNA level and liver histology in patients with chronic HBV infection

BACKGROUND

There is no consensus regarding the relationship between HBV DNA and liver fibrosis, and the relationship between HBV DNA and the degree of liver cirrhosis has not been reported in patients with chronic HBV infection.

METHODS

From January 2011 to December 2016, liver biopsies were performed on 396 patients with chronic hepatitis B and cirrhosis. Assessments of liver fibrosis and cirrhosis were based on the Laennec staging system.

RESULTS

Serum levels of HBV DNA were correlated with fibrosis and cirrhosis (KW = 73.946, P<0.001). Serum HBV DNA level was correlated with mild fibrosis, moderate to severe fibrosis and cirrhosis (P = 0.009, P<0.001, and P<0.001, respectively). The HBeAg-positive group and HBeAg-negative group showed significant differences in HBV DNA levels, and the rates of mild fibrosis, severe fibrosis and cirrhosis were significantly different between these two groups (F = 17.585, P<0.001 and F = 6.017, P = 0.003, respectively). The replication status of the serum HBV DNA affected fibrosis formation as well as cirrhosis (χ2 = 53.76, P<0.001). In the HBeAg-positive group, the sensitivity, specificity and AUC values of HBV DNA as a predictor for mild fibrosis and cirrhosis were 64.3%, 78.94% and 0.818, respectively, and 81.0%, 69.2%, and 0.871, respectively. In the HBeAg-negative group, the sensitivity, specificity and AUC values of HBV DNA for liver sclerosis prediction were 48%, 76.8% and 0.697, respectively.

CONCLUSIONS

Different HBV DNA levels had different effects on the formation of fibrosis and sclerosis in liver tissues. HBV DNA levels can predict mild fibrosis and cirrhosis in liver tissue, which is enhanced in HBeAg-positive patients.

A Noninvasive Score to Predict Liver Fibrosis in HBeAg-Positive Hepatitis B Patients with Normal or Minimally Elevated Alanine Aminotransferase Levels

Noninvasive fibrosis tests are highly needed but have not been well studied in chronic hepatitis B patients with normal or minimally elevated alanine aminotransferase (ALT) levels. This study is aimed at developing a noninvasive score system to predict liver fibrosis in these patients. HBeAg-positive chronic hepatitis B patients with ALT levels of <80 IU/l and liver histology (n = 290) were assigned to training (n = 203) or validation (n = 87) groups. Training group patients were divided into nonsignificant (F0–1) and significant fibrosis (F2–4) according to METAVIR stages. Logistic regression was performed to identify factors for liver fibrosis and develop a score system. The capacity of the score to identify the severity of fibrosis was displayed by receiver operating characteristic curve (ROC) and area under ROC (AUROC) values. Multivariate logistic regression showed that HBeAg (ratios of the sample to the cutoff values (S/CO)) and liver stiffness measurement (LSM; kilopascals (kPa)) were independent factors of liver fibrosis. A score system composed of HBeAg and LSM by assigning a point of 1, 2, or 3 to different HBeAg and LSM levels, respectively, was developed. The scores 2-3, 4, and 5-6 of the sum of HBeAg and LSM points indicated nonsignificant, indeterminate, and significant fibrosis, respectively. The score system had an AUROC of 0.880 and showed similar performance in validation group patients. The accuracy for identifying significant and nonsignificant fibrosis was 77.14% in validation group patients and 71.26% in the entire group of patients. It is suggested that this noninvasive score system can accurately predict hepatic fibrosis and may reduce the need for liver biopsy in HBeAg-positive patients with normal or minimally elevated ALT levels.

A novel noninvasive algorithm for the assessment of liver fibrosis in patients with chronic hepatitis B virus infection

Several noninvasive blood biomarkers have been established for the assessment of liver fibrosis in patients with chronic hepatitis B virus (HBV) infection, but their clinical performance remains inconclusive. Here, we compared the diagnostic performance of these biomarkers and developed a novel algorithm for assessing liver fibrosis. Six hundred and sixteen chronically HBV-infected and treatment-naïve patients who underwent liver biopsy were enrolled and randomly divided into training (N=410) and internal validation cohorts (N=206). One hundred and fifty-nine patients from another centre were recruited as an external validation cohort. Receiver operating characteristic (ROC) curves were used to analyse the performance of the gamma-glutamyltransferase-to-platelet ratio (GPR), red cell volume distribution width-to-platelet ratio (RPR), FIB-4 index, aspartate aminotransferase-to-platelet ratio index (APRI) and HBV DNA level against liver histology, and a novel algorithm was developed using the recursive partitioning and regression tree (RPART) method. In the training cohort, the area under the ROC curve of FIB-4 was significantly higher than that of APRI (P=.038) but was comparable to those of GPR, RPR and HBV DNA; however, the performance of the biomarkers was similar among the validation cohort. The established RPR-HBV DNA algorithm performed better in the training cohort than any individual blood biomarker, and the corresponding sensitivity, specificity, positive predictive value and negative predictive value were 63%, 90%, 72% and 80%, respectively. In the internal and external validation cohorts, the performance of the algorithm in assessing liver fibrosis was also superior to that of other biomarkers. These results suggest that the established RPR-HBV DNA algorithm might improve the diagnostic accuracy of liver fibrosis in treatment-naïve patients with chronic HBV infection, although additional studies are warranted to confirm these findings.

Relationship between virological response and FIB-4 index in chronic hepatitis B patients with entecavir therapy

AIM: To investigate whether long-term low-level hepatitis B virus (HBV) DNA influences dynamic changes of the FIB-4 index in chronic hepatitis B (CHB) patients receiving entecavir (ETV) therapy with partial virological responses.

METHODS: We retrospectively analyzed 231 nucleos(t)ide (NA) naïve CHB patients from our previous study (NCT01926288) who received continuous ETV or ETV maleate therapy for three years. The patients were divided into partial virological response (PVR) and complete virological response (CVR) groups according to serum HBV DNA levels at week 48. Seventy-six patients underwent biopsies at baseline and at 48 wk. The performance of the FIB-4 index and area under the receiver operating characteristic (AUROC) curve for predicting fibrosis were determined for the patients undergoing biopsy. The primary objective of the study was to compare the cumulative probabilities of virological responses between the two groups during the treatment period. The secondary outcome was to observe dynamic changes of the FIB-4 index between CVR patients and PVR patients.

RESULTS: For hepatitis B e antigen (HBeAg)-positive patients (n = 178), the cumulative probability of achieving undetectable levels at week 144 was 95% and 69% for CVR and PVR patients, respectively (P < 0.001). In the Cox proportional hazards model, a lower pretreatment serum HBV DNA level was an independent factor predicting maintained viral suppression. The cumulative probability of achieving undetectable levels of HBV DNA for HBeAg-negative patients (n = 53) did not differ between the two groups. The FIB-4 index efficiently identified fibrosis, with an AUROC of 0.80 (95%CI: 0.69-0.89). For HBeAg-positive patients, the FIB-4 index was higher in CVR patients than in PVR patients at baseline (1.89 ± 1.43 vs 1.18 ± 0.69, P < 0.001). There was no significant difference in the reduction of the FIB-4 index between the CVR and PVR groups from weeks 48 to 144 (-0.11 ± 0.47 vs -0.13 ± 0.49, P = 0.71). At week 144, the FIB-4 index levels were similar between the two groups (1.24 ± 0.87 vs 1.02 ± 0.73, P = 0.06). After multivariate logistic regression analysis, a lower baseline serum HBV DNA level was associated with improvement of liver fibrosis. In HBeAg-negative patients, the FIB-4 index did not differ between the two groups.

CONCLUSION: The cumulative probabilities of HBV DNA responses showed significant differences between CVR and PVR HBeAg-positive CHB patients undergoing entecavir treatment for 144 wk. However, long-term low-level HBV DNA did not deteriorate the FIB-4 index, which was used to evaluate liver fibrosis, at the end of three years.