Introduction
Vanishing bile duct syndrome (VBDS), also known as ductopenia, is a pathological diagnosis defined by loss of interlobular bile ducts in 50% or more portal tracts in a liver biopsy containing at least 11 portal tracts.1 It can be caused by many cholestatic disorders including autoimmune, drug/toxin, genetic, infection, or ischemia.2 Primary biliary cholangitis (PBC) and primary sclerosing cholangitis are two well recognized disorders which can eventually develop VBDS in their later stages.3,4 Limited studies, including case reports or small case series of neoplastic diseases (particularly lymphoma) or drug-induced liver injury (DILI) has also associated these etiologies with VBDS.1,5,6 In 2017, the DILI Network published a 10-year prospective study on drug or supplement induced bile duct loss and at least 12 cases of VBDS were identified in the 363 patients studied.7 However, the study was only based on DILI data, which would not include many other potential VBDS etiologies. Therefore, insufficient information exists on VBDS and its associated histology, clinical course, and long-term prognosis.
The degree of bile duct paucity has been shown to be a good predictor for poor prognosis in patients with either DILI or PBC.7–9 VBDS, as a higher extent of bile duct loss (≥50%), has been associated with advanced disease and poor prognosis.10 However, VBDS has also been observed in early stages of the disease, and disease severity and clinical prognosis can be variable.11 Some patients regain normal liver function, but others may experience persistent, severe, with unremitting jaundice and high levels of cholestatic enzymes, finally leading to liver transplantation (LT) or death.
Risks factors associated with VBDS prognosis remain unclear, but are in part determined by the balance of bile duct destruction and regeneration.12 Considering the heterogeneity of VBDS, the specific precipitating cause may influence a patient’s overall outcome. In the present study, the hypothesis was that VBDS etiology and/or baseline histological features could help predict long-term outcomes. Therefore, this retrospective study investigated various etiologies, clinical and histological features, and long-term outcomes in patients with VBDS and identified several potential risk factors for predicting poor prognosis.
Methods
Study population
In this multicenter retrospective cohort study, medical records and liver biopsy slides were reviewed for patients with VBDS who underwent biopsy either at Beijing Friendship Hospital, China-Japan Friendship Hospital, Peking University First Hospital, Heilongjiang Province Hospital or Tianjin Second People’s Hospital between January 2003 and April 2022. The study was conducted in accordance with the Declaration of Helsinki and all research was approved by the ethical standards for clinical studies by the ethics committee. All patients gave verbal consent to participate in the study.
All included patients were diagnosed based on histological evidence that more than 50% of portal tracts lacked a bile duct in liver biopsies with 11 or more portal tracts.2,13 Partial portal areas were not counted. Patients were excluded if they had ever experienced chronic rejection or graft versus host reaction after LT or bone marrow transplantation, or if they were lost to follow-up.
Baseline data collection
Clinical characteristics at the time of liver biopsy, including age, sex, biochemical indices [alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), albumin (ALB), total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL)], treatment strategies and etiology of VBDS were collected. The starting date was defined as the date of VBDS diagnosis. The duration of follow-up was defined as the interval between the date of diagnosis and the date of either the last visit, or LT, or death.
Enrolled patients were divided into three groups by their etiology, DILI-VBDS, PBC-VBDS, or mixed liver-related diseases (miscellaneous-VBDS). PBC was diagnosed when patients met at two or more of the following criteria: (1) Biochemical evidence of cholestasis, such as the elevation of ALP and GGT; (2) Presence of antimitochondrial antibodies or PBC-specific antinuclear antibodies, like anti-sp100 or anti-gp210; (3) Histologic evidence of nonsuppurative destructive cholangitis.14 DILI was diagnosed when (1) ALT level ≥5 × the upper limit of normal (ULN) or ALP level ≥2 × ULN or ALT level ≥3 × ULN and TB >2 × ULN; (2) Roussel Uclaf Causality Assessment Method score ≥3. A final diagnosis of DILI was confirmed by three hepatologists (XYZ, TTL, and HTY).
Histological assessment of liver biopsy
Formalin-fixed, paraffin-embedded liver samples were routinely sectioned and stained with hematoxylin and eosin, Masson trichrome, reticulin, and cytokeratin 7, and 19. They received the same structured histological evaluation by a pathologist (TLW) and a clinical hepatologist and liver pathologist (XYZ), who were blinded to all clinical information. Discrepancies in interpretation were discussed until consensus was achieved. Histological features included interlobular bile duct injury or loss, cholestasis, cholate stasis, foam cells, portal inflammation, interface hepatitis, and stage of fibrosis. All these features were scored according to the published standard descriptions for DILI15,16 and PBC17,18 (Supplementary Table 1).
Information on clinical outcomes
Follow-up data and clinical outcomes (decompensated cirrhosis, LT, or death) were obtained through interviews and review of electronic medical records. Cirrhosis was diagnosed histologically or clinically based on modified diagnostic criteria proposed by the Chinese Society of Hepatology.19 Decompensated cirrhosis was defined as the occurrence of either ascites, variceal bleeding, or hepatic encephalopathy.19
Statistical analysis
Descriptive statistics were used to detail the baseline characteristics. Continuous data were presented as median and interquartile range. The Mann-Whitney U test was used to compare age, liver biochemistries, follow-up time, and the period from onset to biopsy. The chi-square test was used to compare the categorical variables of etiology, sex, and pathological features. A multivariate Cox proportional hazards model was used to identify prognostic factors associated with long-term survival. Forward stepwise procedures were applied for the final model selection. Additionally, nomograms were developed based on the optimized Cox regression model to facilitate point-of-care risk assessment and calculate the predicted survival probability.20,21 The statistical analysis was performed with SPSS version 20 (IBM Corp., Chicago, IL, USA) and R software version 3.6.1 (R Foundation for Statistical Computing, Vienna, Austria; http://www.r-project.org/ ). For all analyses, p-values <0.05 were considered significant.
Results
Demographic characteristics of VBDS patients
Over a 20 year period, 242 subjects with biopsy-proven VBDS from routine consultant cases (to minimize selection bias) were retrospectively reviewed. A total of 59 patients were excluded from the final analysis, three due to chronic allograft rejection after LT and 56 due to loss of follow-up (Fig. 1). A final total of 183 patients were included, the demographics and laboratory data of whom are shown in Table 1. Eighty-two patients were from China-Japan Friendship Hospital, 68 from Beijing Friendship Hospital, 22 from Peking University First Hospital, seven from Tianjin Second People’s Hospital, and four from Heilongjiang Province Hospital. Supplementary Table 2 shows that similar clinical characteristics were observed among the included and excluded VBDS patients.
Table 1Demographic and laboratory features of patients with vanishing bile duct syndrome
| Characteristics | DILI-VBDS (n=29) | PBC-VBDS (n=118) | Miscellaneous-VBDS (n=36) | p-value |
|---|
| Age in years, median (IQR) | 47.5 (38.2–56.0) | 49.0 (39.0–54.0) | 46.5 (38.0–57.8) | 0.940 |
| Sex, n (%) | | | | 0.002 |
| Male | 10 (34.5%) | 17 (14.4%) | 14 (38.9%) | |
| Female | 19 (65.5%) | 101 (85.6%) | 22 (61.1%) | |
| ALT in U/L | 141 (99.8–179.5) | 76.8 (45–132.5) | 81.55 (48–134.5) | 0.011 |
| AST in U/L | 97 (75–137) | 84.65 (63–116.8) | 86 (51.25–127.8) | 0.548 |
| ALP in U/L | 354.1 (265.8–481.3) | 341 (201–546) | 330 (226.5–488) | 0.917 |
| GGT in U/L | 456 (209–645) | 322 (212–625) | 415 (199–579) | 0.720 |
| ALB in g/L | 40.35 (33.3–43.0) | 38.2 (34.6–41.8) | 37.1 (33.5–40.4) | 0.666 |
| TBIL in µmol/L | 54.4 (19.5–163.6) | 26.76 (16.1–64.9) | 30.85 (18.8–99.7) | 0.084 |
| DBIL in µmol/L | 32.3 (8.3–107.8) | 10.33 (5.42–33.7) | 16 (8–82.3) | 0.042 |
| Clinical outcomes, n (%) | | | | 0.004 |
| No cirrhosis | 22 (75.9%) | 59 (50%) | 14 (38.9%) | |
| Compensated cirrhosis | 2 (6.9%) | 22 (18.6%) | 3 (8.3%) | |
| Decompensated cirrhosis | 0 (0%) | 16 (13.6%) | 3 (8.3%) | |
| Liver transplantation | 3 (10.3%) | 6 (5.1%) | 6 (16.7%) | |
| Liver-related death | 2 (6.9%) | 15 (12.7%) | 10 (27.8%) | |
| UDCA administration | 21 (72.4%) | 115 (97.5%) | 31 (86.1%) | 0.001 |
| Period from onset to biopsy in months | 4.5 (1–14.25) | 13 (1–42.5) | 12 (3–60) | 0.093 |
| Follow-up duration in years | 4.93 (2.79–8.30) | 5.01 (2.38–7.15) | 3.16 (1.54–6.06) | 0.139 |
The median age at diagnosis was 47 (38, 55) years of age, 142 (77.6%) patients were women, 167 had been treated with ursodeoxycholic acid, and usage proportion was similar in patients with or without death/LT. The median time from onset to biopsy was one year and no significant difference was observed in the onset-to-biopsy duration among groups.
Clinical and histological features of VBDS patients
Biochemical indices at time of liver biopsy are shown in Table 1. Median ALP was 340.5 (218.3, 538.5) U/L and GGT was 366 (209.0, 632.0) U/L. Median ALT was 93.5 (48.0, 148.0) U/ L, AST was 87.3 (57.9, 127.0) U/L, and TBIL was 28.8 (17.1,75.3) µmol/L. Histopathological changes are summarized in Table 2. The mean length and number of portal tracts in each liver biopsy was 1.4 (1.2, 1.8) centimeters and 13 (11,15), respectively. Overall, 43% of patients had ≥75% bile duct loss and 51.3% had bile duct loss with ductular reaction, and 25% had hepatocellular cholestasis. Other cholestatic features included canalicular cholestasis (22.4%), cholestasis within Kupffer cells (18.0%), cholate stasis (34.4%), and foam cells (19.7%). Advanced fibrosis (≥F3, Metavir stage) was detected in only 30.6% of patients. Additionally, two distinctive forms of VBDS were observed: 35.5% of patients lacked obvious inflammation and fibrosis and the other 64.5% showed obvious portal inflammation (Ludwig score ≥2) or advanced fibrosis (Supplementary Fig. 1). The correlations between onset-to-biopsy time and histological features are shown in Supplementary Table 3. Time to liver biopsy was not associated with either fibrosis stage or duct loss. However, cholate stasis, a histopathological feature of chronic cholestasis, was positively associated with this time period. Lobular inflammation was negatively associated with the clinical course of VBDS.
Table 2Comparison of histological characteristics of patients with vanishing bile duct syndrome
| Histological features | All patients (n=183) | DILI-VBDS (n=29) | PBC-VBDS (n=118) | Miscellaneous-VBDS (n=36) | p-value |
|---|
| Bile duct loss | | | | | 0.173 |
| ≥1/2 but <3/4, n (%) | 105 | 12 (41.4%) | 40 (37.7%) | 20 (55.6%) | |
| ≥3/4, n (%) | 78 | 17 (58.6%) | 66 (62.3%) | 16 (44.4%) | |
| Periportal CK7+ staining* | | | | | 0.208 |
| <1/3, n (%) | 104 | 20 (83.3%) | 58 (69%) | 23 (82.1%) | |
| ≥1/3, n (%) | 37 | 4 (16.7%) | 26 (31%) | 5 (17.9%) | |
| Ductular reaction | | | | | |
| Absent | 89 | 20 (69%) | 56 (47.5%) | 13 (36.1%) | 0.047 |
| Periportal, small | 66 | 7 (24.1%) | 46 (39%) | 13 (36.1%) | |
| Periportal, branched | 28 | 2 (6.9%) | 16 (13.6%) | 10 (27.8%) | |
| Hepatocellular cholestasis | | | | | |
| Yes | 46 | 12 (41.4%) | 22 (18.6%) | 12 (33.3%) | 0.018 |
| None | 137 | 17 (58.6%) | 96 (81.4%) | 24 (66.7%) | |
| Canalicular cholestasis | | | | | 0.007 |
| Yes | 41 | 11 (37.9%) | 18 (15.3%) | 12 (33.3%) | |
| None | 142 | 18 (62.1%) | 100 (84.7%) | 24 (66.7%) | |
| Cholestasis in Kupffer cells | | | | | 0.195 |
| Yes | 33 | 8 (27.6%) | 17 (14.4%) | 8 (22.2%) | |
| None | 150 | 21 (72.4%) | 101 (85.6%) | 28 (77.8%) | |
| Cholate stasis | | | | | <0.001 |
| Yes | 63 | 1 (3.4%) | 44 (37.6%) | 18 (50%) | |
| None | 120 | 28 (96.6%) | 73 (62.4%) | 18 (50%) | |
| Foam cells | | | | | 0.800 |
| Yes | 36 | 7 (24.1%) | 22 (18.6%) | 7 (19.4%) | |
| None | 147 | 22 (75.9%) | 96 (81.4%) | 29 (80.6%) | |
| Lobular inflammation | | | | | 0.439 |
| None | 3 | 0 (0%) | 2 (1.7%) | 1 (2.8%) | |
| Mild or moderate | 118 | 18 (62.1%) | 73 (61.9%) | 27 (75%) | |
| Severe | 62 | 11 (37.9%) | 43 (36.4%) | 8 (22.2%) | |
| Portal inflammation | | | | | 0.001 |
| Yes | 171 | 7 (24.1%) | 4 (3.4%) | 1 (2.8%) | |
| None | 12 | 22 (75.9%) | 114 (96.6%) | 35 (97.2%) | |
| Interface hepatitis | | | | | <0.001 |
| Yes | 140 | 14 (48.3%) | 18 (15.3%) | 11 (30.6%) | |
| None | 43 | 15 (51.7%) | 100 (84.7%) | 25 (69.4%) | |
| Fibrosis Stage | | | | | <0.001 |
| None | 19 | 3 (10.3%) | 15 (12.7%) | 1 (2.8%) | |
| Stage I–II | 108 | 25 (86.2%) | 65 (55.1%) | 18 (50%) | |
| Stage III–IV | 56 | 1 (3.4%) | 38 (32.2%) | 17 (47.2%) | |
| Different form of VBDS | | | | | <0.001 |
| With portal inflammation or advance fibrosis | 118 | 28 (96.6%) | 72 (61%) | 18 (50%) | |
| Without portal inflammation and advance fibrosis | 65 | 1 (3.4%) | 46 (39%) | 18 (50%) | |
Comparison of VBDS patients with different etiologies
Among all VBDS cases, 118 were caused by PBC, 29 were associated with DILI, and the remaining 36 had miscellaneous etiologies: idiopathic adult VBDS (n=20), primary sclerosing cholangitis (n=9), Alagille syndrome (n=4), and progressive familial intrahepatic cholestasis (n=3). For biochemical measures, ALP, and GGT levels were similar among groups, whereas ALT and bilirubin levels were significantly higher in DILI-VBDS patients (ALT: 141.0 vs. 76.8 vs. 81.5 U/L; DBIL: 32.3 vs. 10.3 vs. 16 µmol/L, DILI vs. PBC vs. miscellaneous, respectively; p<0.05, Table 1).
Histological features are shown in Table 2. DILI-VBDS patients had a significantly higher degree of histological cholestasis, followed by miscellaneous etiologies, than PBC-VBDS patients: hepatocellular cholestasis 41.4% vs. 33.3% vs. 18.6%, cholestasis in Kupffer cells 27.6% vs. 22.2% vs. 14.4%, canalicular cholestasis 37.9% vs. 33.3% vs. 15.3% (DILI vs. miscellaneous vs. PBC, respectively, all p<0.05). Miscellaneous etiologies and PBC-VBDS patients exhibited a significantly higher degree of cholate stasis than DILI-VBDS patients: miscellaneous 50%, PBC 37.6%, DILI 3.4% (p<0.05). Portal inflammation and interface hepatitis were significantly higher in DILI-VBDS patients than in the other two groups: portal inflammation 24.1% vs. 3.4% vs. 2.8%, interface hepatitis 48.3% vs. 15.3% vs. 30.6% (DILI vs. PBC vs. miscellaneous, respectively; all p<0.05). Advanced fibrosis was significantly more common in patients with miscellaneous etiologies and PBC-VBDS than in those with DILI-VBDS: 47.2% vs. 32.2% vs. 3.4%, respectively (p<0.05). Other histological features, such as degree of bile duct loss, lobular necroinflammation, foam cells, and periportal CK7+ staining, were similar across groups.
Follow-up and clinical outcomes of VBDS patients
The median follow-up period was 4.8 (2.0, 7.3) years and nearly half the patients (48.1%) developed compensated or decompensated cirrhosis during that time. Forty-two patients (23.0%) succumbed to an end-point event, 15 to LT and 27 to liver-related death (Table 1). There was a higher proportion of males in the LT/death group than in the no-endpoint group (36% vs. 18%, respectively; p<0.05). The overall 1-, 3-, 5-, and 10-year transplant-free survival rates were 91.0%, 83.0%, 78.0% and 67.2%, respectively.
Risk factors of poor VBDS prognosis
Univariate Cox regression analysis demonstrated that lower serum ALB and higher serum bilirubin at biopsy, but not underlying etiology were associated with higher risk of LT or liver-related death (Supplementary Table 4). After adjusting the multivariate Cox regression, only TBIL (HR 1.017, 95% CI: 1.010–1.023, p<0.05) was significantly associated with LT or death of VBDS patients (Fig. 2A).
Histologically, cholestasis within hepatocytes, canaliculi and Kupffer cells, cholate stasis, foam cells and advanced fibrosis rather than underlying etiology were associated with poor outcome (Table 3). Multivariate analysis showed that hepatocellular cholestasis (HR 2.953, 95% CI: 1.437–6.069; Fig. 3A–C), foam cells (HR 2.349, 95% CI: 1.092–5.053; Fig. 3D–F), and advanced fibrosis (HR 2.524, 95% CI: 1.313–4.851) were independent predictors of poor prognosis. Kaplan-Meier plots of these features are shown in Figure 2B–D.
Table 3Univariate and multivariate Cox regression analysis of histological features associated with liver transplantation or liver-related deaths in patients with vanishing bile duct syndrome
| Histological features | Univariate analysis
| Multivariate analysis
|
|---|
| Hazard ratio (95% CI) | p-value | Hazard ratio (95% CI) | p-value |
|---|
| Degree of VBDS | 1.155 (0.623–2.139) | 0.824 | | |
| Periportal CK7+ staining | 0.939 (0.405–2.178) | 0.964 | | |
| Ductular reaction | 1.427 (0.764–2.662) | 0.264 | | |
| Hepatocellular cholestasis | 4.570 (2.445–8.542) | <0.001 | 2.953 (1.437–6.069) | 0.003 |
| Canalicular cholestasis | 4.434 (2.367–8.303) | <0.001 | | |
| Cholestasis in Kupffer cells cells | 4.348 (2.281–8.286) | <0.001 | | |
| Cholestasis | 2.514 (1.366–4.627) | 0.003 | | |
| Portal inflammation | 1.298 (0.314–5.375) | 0.719 | | |
| Interface hepatitis | 1.216 (0.563–2.627) | 0.619 | | |
| Lobular inflammation | 20.742 (0.001–Inf) | 0.539 | | |
| Fibrosis degree | 2.137 (1.157–3.945) | 0.015 | 2.524 (1.313–4.851) | 0.005 |
| Foam cells | 2.626 (1.396–4.942) | 0.003 | 2.349 (1.092–5.053) | 0.029 |
Correlations were calculated among the key histological features to avoid multivariable interference (Supplementary Table 5). Fibrosis was positively correlated with portal inflammation (r=0.38, p<0.01), interface hepatitis (r=0.36, p<0.01), cholate stasis (r=0.49, p<0.01), and ductular reaction (r=0.32, p<0.01), and negatively correlated with foam cells (r=−0.15, p<0.05). Hepatocellular cholestasis correlated negatively with portal inflammation (r=−0.26, p<0.01) and positively with foam cells (r=0.40, p<0.01). The degree of VBDS correlated positively with hepatocellular cholestasis (r=0.24, p<0.01) and negatively with fibrosis stage (r=−0.15, p<0.05). Fibrosis stage correlated weakly with cholestasis, and collinearity diagnostics demonstrated that there was no collinearity among the three key histological risk factors (all variance inflation factors, p<3).
Nomogram construction and validation
Based on the three independent histological prognostic factors, a nomogram was developed for the prediction of transplant-free survival in VBDS patients (Supplementary Fig. 2A). Hepatocellular cholestasis was the factor that contributed most to prognosis, followed by advanced fibrosis and foam cells. The 3-, 5-, and 10-year transplant-free survival for VBDS patient was predicted by the cumulative score (Table 4). The predictive performance of the nomogram was measured by concordance index and calibrated with 1,000 bootstrap samples to decrease the overfit bias. The nomogram demonstrated good accuracy in estimating the risk of death or LT, with an unadjusted concordance index of 0.746 (95% CI: 0.706–0.785; Supplementary Fig. 2B). Furthermore, calibration plots showed good agreement of the above-mentioned risk factors.
Table 4Estimated survival up to 10 years according to risk factor
| Hepatocellular cholestasis | Foam cells | Fibrosis degree | 3-year survival, % | 5-year survival, % | 10-year survival, % |
|---|
| − | + | I–II | 83.97 | 80.04 | 65.25 |
| − | − | I–II | 91.33 | 89.09 | 80.13 |
| − | + | III–IV | 71.41 | 65.12 | 43.93 |
| − | − | III–IV | 83.97 | 80.04 | 65.25 |
| + | + | I–II | 52.26 | 43.75 | 20.49 |
| + | − | I–II | 71.41 | 65.12 | 43.93 |
| + | + | III–IV | 28.63 | 20.03 | 4.71 |
| + | − | III–IV | 52.26 | 43.75 | 20.49 |
Discussion
VBDS does not often accompany with poorer outcomes and seeking for the potential risk factors associated with death or LT is interested. Of the 183 patients studied, half recovered or maintained their present disease course and the other half progressed to cirrhosis or cirrhosis-related complications; Moreover, 23% died of end-stage liver disease or required LT. Etiology was not associated with outcome. Clinically, serum bilirubin level was most associated with transplant-free survival. Histologically, hepatocellular cholestasis, foam cells, and advanced fibrosis were predictive of poor prognosis.
In this study, high TBIL was associated with poor VBDS outcomes. This result was compatible with two recent studies of VBDS associated with DILI.7,22 Hyperbilirubinemia has also been identified as an independent risk factor for poor prognosis in PBC.14 This phenomenon was also in accordance with the histological presence of hepatocellular cholestasis as an independent predictor of the survival of VBDS patients, suggesting that cholestasis is a hallmark of decompensated bile drainage. Although more than 50% portal tracts lacked a bile duct, only one-third of VBDS patients had clinical jaundice or histological hepatocellular cholestasis. Collective compensatory drainage by a reserve interconnected biliary network can partially explain the extended period of jaundice-sparing despite extensive duct loss.2,23 Furthermore, whether alteration of hepatobiliary transporter expression was associated with disease progression needs to be studied further.24 Finally, it was not intermediate hepatocytes (CK7-positive), an early histological sign of cholate stasis, but foam cells, a typical feature of late-stage cholate stasis, that were associated with poor outcomes. Thus, chronic cholestatic features (hepatocellular cholestasis and foam cells) were associated with adverse outcomes in VBDS patients.
Advanced fibrosis rather than portal inflammation was independently associated with poor prognosis in VBDS. The present cohort suggested that there were two distinctive forms of VBDS: one associated with obvious portal inflammation and advanced fibrosis, and the other being “bland” duct loss without obvious portal inflammation or fibrosis (Supplementary Fig. 1). Inflammation seemed to be less predictive of prognosis in patients with bile duct loss. Previous research reported that the necroinflammatory index was not associated with clinical outcomes in patients with DILI-related bile duct loss.7 Advanced fibrosis has been well recognized as a hallmark of poor prognosis in a variety of liver diseases,25 such as chronic hepatitis B and C26 and nonalcoholic fatty liver disease.27 Portal and periportal fibrosis have been shown to be correlated with poor prognosis in PBC.28,29 Fibrosis stage has also been associated with poor outcome in children with bile duct paucity.25 The present data suggested that advanced fibrosis together with bile duct loss was associated with an even worse clinical outcome in patients with VBDS regardless of the underlying etiology; therefore, timely evaluation for LT may be warranted. VBDS can occur even in early stages of disease, and not all patients with advanced stages experience VBDS. In this study, 69.3% of VBDS patients were in the early stage of fibrosis (DILI 96.5%, PBC 67.8% and miscellaneous 52.8%).
Bile duct loss, especially at the 50% cut off, has been regarded as a histological hallmark of poor prognosis.7,30,31 Our previous data showed that a loss of only 25% of bile ducts was independently associated with liver disease chronicity.32 In the current study, a loss of 75% or more did not seem to be associated with a worse outcome when compared to patients with 50% or more duct loss; thus, implying that a greater degree of bile duct loss may not have an additive effect on the prognosis of VBDS patients. However, this hypothesis requires evidence from further studies and the underlying mechanism must be probed. Homeostasis of bile ducts is maintained by a balance between cell death and cell renewal or regeneration,33 and ductular proliferation often coexists with interlobular bile duct loss.23 Previous studies have demonstrated that the regenerative ability of interlobular bile ducts was an important factor determining the prognosis of DILI-VBDS.34 In this study, no significant difference in ductular reaction (or ductular proliferation, 48.2% vs. 61.9%) or extent of CK7-positive hepatocytes (a kind of bipotent hepatic progenitor cell, 27.5% vs. 21.9%), was observed between the two groups. Although etiology was not independently related with VBDS prognosis in this study, the clinical outcome was influenced by the cause of the initiating insult and the degree of injury.33 DILI-VBDS generally had a better prognosis than those with PBC-VBDS.35 VBDS associated with COVID-19 is usually transient and resolve with disease resolution, but some COVID-19 related ductopenia is severe.36
The study has limitations. First, a minority of patients had an undetermined etiology, and the sample sizes of DILI- and miscellaneous-VBDS were small. That might have been PBC patients have a higher incidence of VBDS than other etiologies. Second, although the study was retrospective in nature, to our knowledge, this is the largest cohort from different providences of China with long-term follow-up outcome data worldwide. The identified risk factors need to be further verified in a prospective cohort study.
Conclusions
In conclusion, of the 183 VBDS patients studied, half progressed to cirrhosis and 23% experienced LT or liver-related death within 2 years of diagnosis. Histological factors such as hepatocellular cholestasis, foam cells, and advanced fibrosis rather than the underlying etiologies of VBDS were independently associated with poor prognosis. The present study provides new evidence to support early liver histological evaluation, as a critical modality for better stratifying high-risk patients with VBDS.
Supporting information
Supplementary Table 1
Scoring of histological lesions of VBDS in the liver biopsy specimens.
(DOCX)
Supplementary Table 2
Demographic and laboratory features of patients with all VBDS patients.
(DOCX)
Supplementary Table 3
Correlation coefficient by Spearman’s rank between histological features and time period from onset to liver biopsy.
(DOCX)
Supplementary Table 4
Univariate and multivariable Cox regression analysis of clinical and biochemical characteristics associated with liver transplantation or liver-related deaths in patients with vanishing bile duct syndrome.
(DOCX)
Supplementary Table 5
Correlation coefficient by Spearman’s rank between histological features.
(DOCX)
Supplementary Fig. 1
Histological features of the two different forms of VBDS.
(A–C) Patient with liver biopsy displaying “bland” ductopenia without obvious inflammation or significant fibrosis (A: Hematoxylin-eosin; B: Masson trichrome; C: Cytokeratin 7); (D–F) Patient with liver biopsy exhibiting ductopenia associated with portal-periportal inflammation and advanced fibrosis (D: Hematoxylin-eosin; E: Masson trichrome; F: Cytokeratin 7). VBDS, vanishing bile duct syndrome.
(DOCX)
Supplementary Fig. 2
Nomogram to estimate the risk of transplant-free survival rate in VBDS patients and validation plot of the predictive performance of the nomogram.
(A) The nomogram to estimate the risk of transplant-free survival rate in patients with VBDS. Each variable was given a point on the basis of the nomograms and by adding the given points of all factors, we finally obtained the total points to estimate 3-, 5- and 10-year probabilities of transplant-free survival of the individual patient from the nomogram. (B) Validity of the predictive performance of the nomogram. C-index (0.746) represents the satisfactory prediction performance of our model. VBDS, vanishing bile duct syndrome.
(DOCX)
Abbreviations
- ALB:
albumin
- ALP:
alkaline phosphatase
- ALT:
alanine aminotransferase
- AST:
aspartate aminotransferase
- DBIL:
direct bilirubin
- DILI:
drug-induced liver injury
- GGT:
gamma-glutamyl transpeptidase
- IBIL:
indirect bilirubin
- LT:
liver transplantation
- PBC:
primary biliary cholangitis
- TBIL:
total bilirubin
Declarations
Ethical statement
The study was conducted in accordance with the Declaration of Helsinki and all research was approved by the ethical standards for clinical studies by the Ethics Committee.
Data sharing statement
The data used to support the findings of this study are available from the corresponding author at zhao_xinyan@ccmu.edu.cn upon request.
Funding
This work was supported by National Natural Science Foundation of China (No. 82100633 to LTT).
Conflict of interest
JJ has been an executive associate editor of Journal of Clinical and Translational Hepatology since 2013. The other authors have no conflict of interests related to this publication.
Authors’ contributions
Study concept and design, (XZ, JJ), acquisition, analysis, or interpretation of data (TL, XH, HY), drafting the manuscript (TL), critical revision of the manuscript for important intellectual content (AW, JL, TW), statistical analysis (TL, ML), study supervision (JX, XlH, JL, WD).