This study evaluated the different risk factors of future LT for patients with BA living with jaundice-free native liver at 1 year after PE. The patients with BA have lifelong risk for LT and require lifelong follow-up. They have various life events ahead and it is important to know the risk of LT for decision on appropriate follow-up intervals, scheduling of detailed examinations and, for women, the timing of pregnancy. Furthermore, prognostic model is needed to accurately and objectively predict prognosis. These factors included the demographic characteristics of the patients, blood test values, presence of BL and cholangitis, and history of bleeding. Among these parameters, the presence of BL was the strongest risk factor of future LT.
BL is an intrahepatic cystic lesion that occurs after PE in 6.4–26% of patients with BA [8]. The prognosis of patients with BA who presented with BL had been investigated, and BL was considered a risk factor of cholangitis, which leads to LT. [8–12]. In particular, compared with a simple cyst, cyst with a shape type such as multiple or bead-like patterns is associated with a worse prognosis [12–14]. In our study, at year 1 postoperatively, the presence of BL was the most influential risk factor for subsequent LT. Other parameters were found to have an impact on prognosis in the univariate analysis. However, none of the factors affected prognosis in the multivariate analysis with BL. By contrast, some parameters were useful in predicting prognosis. The AUC can improve if DB and TBA are added as prognostic parameters, in contrast to other parameters. Therefore, the two models were developed with DB and TBA. The predictive ability of the two models was comparable. However, calibration of Model 1 was not good. Hence, Model 2 was selected.
The LT group did not have a higher number of cholangitis until 1 year postoperatively than the NLS group. Furthermore, we found no significant difference in the number of cholangitis in comparison between the patients with and without BL (1 vs. 1, p = 0.252). The rate of cholangitis is generally high in the early postoperative period, and the development of BL takes time [10, 15]. Therefore, BL and LT were not related to the number of cholangitis up to 1 year after PE. Another research has reported similar results. That is, BL did not increase the number of cholangitis in the short-term [9]. The research also reported that BL increases the number of cholangitis in the long-term. Patients living with native liver at 1 year postoperatively can have long-term NLS. Hence, so comparison in only those patients in our study might have identified BL as a risk factor for subsequent LT. Further, based on the Kaplan–Meier curves, patients with BL had a significantly poor prognosis with consideration of the passage of time. In relation to its natural course, BL rarely improves. Thus, if BL occurs, it can increase the risk of LT during the rest of the patient’s life. Although this was a 10-year study, patient prognosis may still differ within in a longer period of time.
The causes of subsequent LT vary. The most common cause was uncontrollable cholangitis in patients with BL. However, uncontrollable cholangitis was the cause of LT in less than half of all cases. According to previous studies reporting an association between cholangitis and BL, BL may be a cause of uncontrollable cholangitis. However, there was no significant difference in the incidence of uncontrollable cholangitis between patients with and without BL. BL with cholangitis was actively treated via percutaneous transhepatic biliary drainage or internal intestinal drainage in our institution [8, 14, 16, 17]. As a result, two patients in the LT group and four in the NLS group had a successfully controlled cholangitis after drainage. Recurrent cholangitis with BL did not always lead to LT. Our study revealed that in the presence of BL, not only cholangitis but also hepatopulmonary syndrome, gastrointestinal hemorrhage, and growth retardation with impaired liver function have resulted in LT. Thus, BL can be associated with progressive fibrosis of the liver and poor liver function.
Age at surgery, which is the most common prognostic factor, had no significant impact on future LT in patients with BA living with native liver at 1 year after PE. This result might have been caused by different demographic characteristics in the current and previous research. Previous studies investigating age at surgery have analyzed all types of patients, including those who have never been cleared of jaundice [1, 2, 4]. However, this study only analyzed jaundice-free patients with native liver survival at 1 year postoperatively. Patients who were not successfully cleared of jaundice often require early LT. Therefore, none of these patients was included in our study. Due to this difference in cohort, age at surgery could not be considered a prognostic factor at this time point.
Relationship between the liver tissue findings at the first surgery and the occurrence of bile lake was confirmed in this investigation. In total, 27 patients finally experienced the occurrence of bile lake until now. Of these, four patients pathologically diagnosed with cirrhosis. The degree of fibrosis and inflammation varied and ranged from mild to severe. No relationship seemed to exist between the severity and the occurrence of bile lake. Cholestasis was not described in detail and could not be considered. We confirmed this from the pathology at PE, and we will investigate it in more detail.
This study had several limitations. First, it had a retrospective, historical-control, single-center design. Hence, multicenter prospective studies should be performed for a more accurate analysis There were only two parameters included in the multivariate analysis due to the small sample size. BA is a rare disease. Therefore, a multicenter analysis should be performed to collect a large sample size. The risk of BL was investigated. However, various characteristics such as the number, form, and size of were not compared. The follow-up period was at least 3 years. Nevertheless, patients with BA occasionally require LT 3 years after PE. Hence, further follow-up is required to consider long-term prognosis. Although, we checked the usefulness of the risk score model by discrimination and calibration, cross validation was required for assessing the accuracy of the model in more detail. However, the number of the cases in this study was insufficient for the analyses. Therefore, we will test the usefulness of the model either by accumulating more cases or using data from other institutions