Introduction

Autoimmune liver disease (AILD) is a rare disease in children. It includes autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and “overlap syndromes” of AIH with PBC or PSC [1]. However, in children only AIH-PSC overlap syndrome, also known as autoimmune sclerosing cholangitis (ASC), has been recognized [2]. AIH is caused by an immunologically mediated damage to the hepatocytes and is defined by the presence of hypergammaglobulinemia (IgG), seropositivity for circulating autoantibodies, and interface hepatitis on histological liver examination in the absence of a known etiology [3, 4]. ASC is a rare chronic inflammatory disorder that affects the intrahepatic and/or extrahepatic biliary tree, leading to bile duct and liver fibrosis [5, 6].

Early diagnosis and treatment are essential, as this is one of the few treatable causes of pediatric liver disease. Over the years, liver transplantation has emerged as an important therapeutic option for children with cirrhosis and end-stage liver disease (ESLD) due to AILD.

It is estimated that around 10% to 15% of patients presenting with AIH will require liver transplant (LT) during their life for complications of either ESLD or acute liver failure (ALF) [7]. AIH is a rare indication for LT; it accounts for 2% to 5% of pediatric LTs performed in Europe and the USA [3, 8, 9]. Similarly, ASC accounts for 2% to 3% of LT performed in children [3, 10].

The liver transplantation program has been very well established in India over the last 20 years [11]. However, there is limited literature on pediatric liver transplantation in AILD to date especially in the Asian population. This case series aims to study the demographic profile, clinical characteristics, outcomes, and predictors of mortality of pediatric AILD subjects who underwent liver transplantation at our LT center. To the best of our knowledge, ours is the first report detailing 10 years of experience of pediatric liver transplants, to treat AILD, in the Indian subcontinent.

Methods

Study design

We did a retrospective search of our inpatient records for the last 10 years (1 July 2010 to 31 May 2020). We included children referred to our liver transplant center with a diagnosis of AIH or ASC who received first liver transplantation at our center.

The original diagnosis of AIH/ASC had been made on presentation, as was based on classical criteria to diagnose AIH and ASC in children (abnormal hepatic function tests and IgG, presence of autoantibodies, compatible histology when available, and exclusion of other probable diagnosis). AIH was classified according to seropositivity for smooth muscle antibody (SMA) and/or antinuclear antibody (ANA) as autoimmune hepatitis type 1 (AIH 1), or anti-liver kidney microsomal antibody (LKM-1) and/or LC 1 as autoimmune hepatitis type 2 (AIH 2), seronegative (negative ANA/anti-smooth muscle antibody [ASMA]/anti-LKM-1). ASC was diagnosed on the basis of biliary involvement with features of AIH (abnormal cholangiographic study and/or evidence of histological confirmation of biliary disease) [12].

ALF was defined as per the Pediatric Acute Liver Failure (PALF) study group as biochemical evidence of acute liver injury in a child with no known evidence of chronic liver disease (CLD) with coagulopathy (defined as prothrombin time [PT] ≥ 15 s or international normalized ratio [INR] ≥ 1.5 not corrected by vitamin K in the presence of encephalopathy, or PT >20 s and INR >2.0 in patients without encephalopathy) [13]. Patients who had hepatic dysfunction manifesting as acute hepatic insult with jaundice and coagulopathy complicated within 4 weeks by clinical ascites and/or encephalopathy in a previously diagnosed or undiagnosed CLD were classified as having acute-on-chronic liver failure (ACLF) as per Asia Pacific guidelines. Patients who had previously diagnosed CLD complicated after 4 weeks with variceal bleed, ascites, and/or hepatic encephalopathy were classified as decompensated CLD [14].

We extracted the demographic, clinical, and biological data from medical records. We recorded the details including age, sex, body mass index (BMI), age of onset of symptoms, classification of AIH, clinical presentation, laboratory investigations (hematological, biochemical, radiological, and histopathological), information on extrahepatic autoimmune disorders (EHADs), Pediatric end-stage liver disease (PELD)/model for end-stage liver disease (MELD) score and severity, Child-Turcotte-Pugh (CTP) score, indication of liver transplant, and family history, after ethical committee approval. Findings of esophageal endoscopy were documented, graded as per standard definitions [15].

All patients received grafts from living donors. As per the Government of India guidelines, all transplants were performed with related donors. Donors underwent a complete medical examination and screening with all investigations as per the international living donation guidelines [16]. Initial immunosuppressive regimen was based on three drug regimens (methylprednisolone, tacrolimus, and mycophenolate mofetil [MMF]) as per our institutional protocol. Immunosuppressants were started on first postoperative day if there were no contraindications. Methyl prednisolone was started at 2.5 mg/kg on postoperative day 1 followed by 2 mg/kg, 1.5 mg/kg, and 1 mg/kg, respectively on postoperative days 2, 3, and 4.This was followed by oral prednisolone 1 mg/kg daily, which was tapered gradually to continue low doses in follow-up for long periods with adequate monitoring. Tacrolimus was started at 0.05–0.1 mg/kg/day in two divided doses. Tacrolimus level of 8–10 ng/mL was maintained in the initial 1–2 months, followed by gradual tapering of the dose over time to achieve long-term immunosuppression levels of 4–6 ng/mL beyond 1 year post-LT. MMF was started as 15 mg/kg initially with increasing doses gradually as tolerated. In children who did not tolerate MMF, azathioprine was used as a once-a-day alternative started at a dose of 0.5 mg/kg and gradually increased to 1.5 mg/kg. Adequate antibiotic prophylaxis with broad-spectrum antibiotics and antifungal prophylaxis was given to all the patients as per standard institutional protocol.

Pre-LT and post-LT data were analyzed and recorded. It included intraoperative course, duration of hospital stay, post-transplant medical and surgical complications, biopsy-proven rejection, outcome, explant histopathological examination, graft survival, and patient survival. Dates of last medical examination or death were considered the end of follow-up.

Statistical analyses

Data entry was done in the Microsoft Excel spreadsheet and final analysis was done using Statistical Package for Social Sciences (SPSS) software, (IBM, Chicago, USA). Frequencies were applied to present qualitative data. Continuous variables with normal distribution were presented as the mean ± standard deviation (SD). Continuous variables with skewed distribution were reported as median with 25th and 75th percentiles (inter-quartile range). The data normality was checked using the Kolmogorov-Smirnov test. The relationship between the continuous variables was analyzed using the Mann-Whitney test (for two groups) and Kruskal-Wallis test (for more than two groups) when not normally distributed. Variables with normal distribution were analyzed using an independent t test (for two groups) and analysis of variance (ANOVA) test (for more than two groups). The categorical variables were analyzed using Fisher’s exact test. Multivariate logistic regression was used to find out significant risk factors for mortality. For statistical significance, p-value of less than 0.05 was considered statistically significant.

Results

Study population

The baseline characteristics, clinical parameters, and laboratory values in the study population are described in Table 1. The study population consisted of 13 children ((F/M: 11/23 [AIH 9, ASC 4]) from 1 July 2010 to 31 May 2020. All children were referred to our center with a diagnosis of AILD and underwent their first LT. Mean BMI was 17.89 ± 4.53. AIH accounted for 69.2% (n = 9) of the cases and ASC for 30.8% (n= 4). Type 1 AIH accounted for 38.4% (n = 5) of the cases, type 2 AIH for 15.3% (n = 2), seronegative AIH (SN AIH) for 15.3% (n = 2), and ASC for 30.8% (n = 4). Baseline characteristics of children with autoimmune hepatitis type 1 (AIH 1), autoimmune hepatitis type 2 (AIH 2), seronegative autoimmune hepatitis (AIH SN), and ASC were compared (Table 2). There was no significant difference in between the groups. Two children had extrahepatic autoimmune disorders (EHADs). This included 2 children with ASC (2/4), one with hypothyroidism and another with ulcerative colitis (confirmed with ileocolonic biopsy), respectively. There was no other associated extrahepatic autoimmune diseases.

Table 1 Depicting baseline characteristics of liver transplant recipients with autoimmune liver disease and group comparison of survivors and non-survivors (n=13)
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Table 2 Depicting the baseline characteristics of post-transplant children distributed according to the type of autoimmune liver disease
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Diagnosis with histopathological confirmation was made before presentation in 76.9% of children (n=10). Mean age of diagnosis of liver disease was 8.92 ± 5.4 years. Mean age at liver transplantation was 12.08 ± 3.84 years. Nearly a half (n=6) had symptoms within 1 to 5 years before they were referred to our center for transplantation. Three children who were referred to our center with acute presentation (2 with ACLF, 1 with ALF) were taken up for transplantation without histopathological confirmation. These children were classified on the basis of auto-antibodies and exclusion of other probable etiologies.

Two children with ACLF (n=3) had AIH 1 and 1 had AIH 2. Out of 3 children who presented with ACLF, 2 children were unmasked by acute hepatitis A infection, and 1 child had acute hepatitis E infection. Mean (SD) INR of children with AIH 1 (n=5) was the highest (3.2 ± 2.18). The leading indications for LT were decompensated chronic liver disease (n=8 [61.54%]) and acute-on-chronic liver failure (n = 3 [23.08%]) followed by acute liver failure (n =1 [7.7%]), and recurrent cholangitis and growth failure (n=1 [7.7%]). Except the latter, all patients presented to our center in a decompensated state. The median PELD/MELD score at presentation was 24 ± 12.81. More than two-third (84.6%, n=11) children were classified as Child-Pugh C.

Living-related LT was done in all patients. Mother was the donor in 46% of children (n=6) followed by father (30.77, n=4). Siblings donated liver in 3 (23.1%) children. All the donors had uncomplicated peri-operative course and follow-up. The graft characteristics are described in Table 1.

Outcomes

Postoperative complications reported after LT included diarrhea (n = 2) and pneumonia (n = 1); surgical complications: jejunostomy site bleed (n = 1); and tacrolimus toxicity: headache and tremors (n = 1) and vascular complications (n = 1). The complications were resolved with medical or surgical (on a case-by-case basis) intervention, and all patients with AIH 1 were discharged with satisfactory graft function. Both the children with AIH 2 could not be saved (100%). Seventy-five percent of children with ASC (n=4) were discharged with good graft function. The median duration of postoperative hospital stay was 27 days ranging from 17 to 87 days. All the surviving children had functioning grafts until the completion of this study.

Eight (61.54%) and 6 (46.15%) children had received steroids and azathioprine, respectively before presentation. All children with ASC (n = 4) had received ursodeoxycholic acid (UDCA) before presentation. 15.38% (n = 2) and 7.7% (n=1) of children had received second-line therapy with sirolimus and mycophenolate mofetil respectively. Clinical characteristics of the three patients (23%) who died after transplantation are depicted in Table 3. One-year patient survival rate was 76.9% (10/13) in our series. However, three of our patients who were discharged were lost to follow-up after the first year. Rest all patients have been doing well in their scheduled follow-ups with no relapse or need for re-transplant. Five-year post-transplant survival rates have been 70% (7/10).

Table 3 Depicting clinical characteristics of 3 patients with autoimmune liver disease who died after liver transplantation
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The baseline characteristics between survivors and nonsurvivors are detailed in Table 1. On univariate analysis, lower platelet count, AIH 2, and PELD/MELD score were found to be significant predictors of mortality. However, on further interpretation with multivariate analysis, no statistical significance was found. As our dataset is small, the significance of statistical analysis needs validation with further multicentric studies.

Discussion

AIH is a rare indication for LT. In patients of autoimmune liver disease with ESLD and intractable symptoms, or those presenting with fulminant liver failure not responding to steroid treatment, LT is considered as the only therapeutic option.

The transplant rate for AIH is variable ranging up to 55% [17,18,19,20,21]. The results of our study (13/244, 5.33%) are comparable to the largest reported series on outcomes following pediatric LT worldwide [6, 9].

We found a male predominance in children (84.6%) transplanted with AILD. Most of the other pediatric series have demonstrated a female predominance of AILD [9, 12]. Cultural barriers with a bias against the girl child and clear male predominance in patients undergoing the procedure are the problems that still exist in India [22]. This could explain the gender distribution in the present study. Mean age at LT was 12.08 ± 3.84 years in our series, which is comparable with another recent study by Couchonnal et al. (10 ± 5.3 years) [23].

Majority (61.5%) of children with AILD had decompensated liver disease at presentation comparable to the other studies from nontransplant centers in India [24,25,26,27,28,29]. There is variable data from the other parts of the world. In the Kings College Series [19], ALF has been reported as the most common indication of AILD children listed for transplant (45%) whereas studies from other parts of the world have reported results similar to ours with around 60% AILD children listed for transplant presenting with decompensated liver disease [9].

Acute liver failure and acute-on-chronic liver failure were the indication for LT in 7.7% and 23.1% of children. respectively. Other pediatric cohorts from the world have reported varying rates (25% to 40%) [6, 9, 16]. The results could be attributed to a possible underrepresentation due to predominantly living donor LT services in India, lack of a national transplant and organ sharing system, lack of awareness of ALF as a medical emergency, concerns regarding donor’s quality of life, financial implications, and delay in referral to a transplant center.

The median PELD/MELD score (IQR) at presentation was 24 (IQR 12–36) in our study which was higher than the median MELD/PELD scores observed in the largest reported cohort of pediatric patients receiving LT for AILD in the world (MELD/PELD score,18: PSC, 17: AIH) [4]. Our patients had higher MELD/PELD scores at the time of transplant than other previously reported studies in AIH (10.8 ± 1.7) and PSC (6.1 ± 1.7) in other parts of the world [9, 10]. Our higher scores could be reflective of worsening disease at the time of referral and could reflect late referral to our center.

Of the 3 mortalities in patients transplanted for AILD, sepsis was the most common cause of death, comparable to earlier reported data from the west [6]. Two children who died had ACLF in our series, which has been reported to have lower patient survival [22]. No patient had biopsy-proven rejection, re-transplantation, or recurrence in our series. All the surviving children had functioning grafts until the completion of our study. It has been reported in other pediatric cohorts with AIH [23, 30, 31]. The reported recurrence rate of AIH is variable. It is dependent on multiple factors including the criteria used for diagnosis, the immunosuppressive regimen, length of follow-up, and performance of biopsies [3]. Mean observed time from LT to recurrence is 5 years. It has been reported in the range of 36% to 68% after 5 years [32]. Recurrence rates of AIH tend to increase with time. The mechanisms of recurrent AIH are not well-described, but risk factors include suboptimal immunosuppression, corticosteroid dosing and weaning, human leukocyte antigen (HLA) phenotype, and severity of disease in native liver at the time of LT [3, 33,34,35,36,37]. Our center’s practice of maintaining patients transplanted for AIH on long-term steroid use could be a significant factor in reducing recurrence in our cohort. In the study by Couchonaal et al., a long follow-up period of 30 years post-transplant has reported a comprehensive description of long-term survival showing 20% recurrence [23]. Further studies with longer follow-up and larger sample size would be prudent to analyze the recurrence of AILD post-transplantation in children.

The available literature on devising pediatric diagnostic scores from adults have highlighted the challenges faced in fulminant hepatic failure especially in pediatric populations [38]. Liver transplantation is the only definitive treatment in most patients with ESLD in AILD. Its outcome varies worldwide depending on the etiology, organ availability, and various other factors. Our survival rates are at par with some busy pediatric transplant centers around the world [9, 39]. The King’s series have demonstrated long-term survival rates of 62.5% [10]. In the large pediatric cohort by United Network for Organ Sharing (UNOS) registry, Jossen and colleagues have reported better patient survival rates (91.4%). Their median MELD/PELD scores at the time of transplant though were lower compared to our series [6]. This highlights the importance of early referral of such patients to a transplant center, which could improve the overall survival. There is limited data on prognostic factors for patient and graft survival in post-transplant children with AILD. Though statistical significance is limited in a small sample size, AIH 2 has been identified as a significant predictor of mortality in our cohort similar to the results described recently by Couchonaal et al. [23].

Our study is limited by the small number of patients. Our study paves the way for increasing awareness among liver physicians, prompting a more robust multicentric study in our country with a larger sample size for better analysis.

To conclude, LT remains the best therapeutic option for children with complications of ESLD with AILD. After instituting appropriate treatment, early referral of such patients to an equipped center should be facilitated. Despite the complications, the graft and patient survival rates are encouraging, and are comparable with the best centers worldwide. Ours is the first report detailing the experience with pediatric liver transplants done for AILD, in India.