Observation on therapeutic efficacy of ursodeoxycholic acid in Chinese patients with primary biliary cirrhosis: a 2-year follow-up study

Abstract

The efficacy of ursodeoxycholic acid (UDCA) on long-term outcome of primary biliary cirrhosis (PBC) has been less documented in Chinese cohort. We aimed to assess the therapeutic effect of UDCA on Chinese patients with PBC. In the present study, 67 patients with PBC were treated with UDCA (13–15 mg∙kg^-1∙day^-1) and followed up for 2 years to evaluate the changes of symptoms, laboratory values and histological features. As the results indicated, fatigue and pruritus were obviously improved by UDCA, particularly in patients with mild or moderate symptoms. The alkaline phosphatase and γ-glutamyl transpetidase levels significantly declined at year 2 comparing to baseline values, with the most profound effects achieved in patients at stage 2. The levels of alanine aminotransferase and aspartate aminotransferase significantly decreased whereas serum bilirubin and immunoglobulin M levels exhibited no significant change. Histological feature was stable in patients at stages 1–2 but still progressed in patients at stages 3–4. The biochemical response of patients at stage 2 was much better than that of patients at stages 3–4. These data suggest that, when treated in earlier stage, patients in long-term administration of UDCA can gain favorable results not only on symptoms and biochemical responses but also on histology. It is also indicated that later histological stage, bad biochemical response and severe symptom may be indicators of poor prognosis for UDCA therapy.

Keywords

primary biliary cirrhosis / ursodeoxycholic acid / Chinese / biochemical response / therapeutic efficacy

Introduction

Primary biliary cirrhosis (PBC) is a kind of slowly progressive cholestatic disease, which mainly targets the cholangiocytes of the interlobular bile ducts in the liver. PBC is very rare with incidence ranged from 0.7 to 49 per million per year and prevalence ranged from 6.7 to 402 per million [1]. Without treatment, PBC has been identified for a significantly increased mortality rate over long-term follow-up when compared with relevant population data [2,3]. In a proportion of patients, PBC may be both clinically and biochemically asymptomatic. When diagnosed, many cases had already progressed to severe jaundice or even liver failure, so that they missed the optimal therapy-timing. Recently, PBC has been diagnosed earlier in its clinical course and the incidence and prevalence of PBC in Chinese people is also ascending. Many explanations may be provided, e.g., true increase due to increased exposure to environmental factors, earlier diagnosis, improved care, and increased awareness of clinician and patients.

The current gold standard of medical therapy for PBC is long-life administration of ursodeoxycholic acid (UDCA) at the dose of 13-15 mg∙kg^-1∙day^-1. In China, UDCA therapy is the single treatment for most patients, because the use of orthotopic liver transplantation has not become widespread yet. Early in 1987, Poupon and colleagues first reported PBC patients could benefit from UDCA treatment [4]. Several clinical trials had been reported since then. Most showed that UDCA could markedly improve liver biochemistry, delay histological progression [5-7] and prolong survival without liver transplantation, although no significant effects on fatigue or pruritus were observed in these large trials [8-10]. There were also controversial voices demonstrating that long-term UDCA therapy did not have many effects on delaying the histological progression [11,12] or development of liver decompensation [6,12]. The relevant reports focus on white people in European and American area.

For the past few years in China, although more attention has been paid to research on autoimmune liver disease and the importance of liver biopsy has been realized, long-term follow-up about therapeutic efficacy of UDCA has been less documented in Chinese cohort. Our primary objective is to observe the long-term effect of this agent on Chinese patients with PBC.

Materials and methods

Study subjects and diagnostic criteria

Patients admitted in our hospital from March 2005 to May 2008 were enrolled in this study. Diagnosis of PBC was defined according to descriptive criteria revised by American Association for the Study of Liver Disease (AASLD) in 2000 [13]: (1) biochemical evidence of cholestasis with elevation of alkaline phosphatase (ALP) and γ-glutamyl transferase (γ-GT) and without evidence of extrahepatic biliary obstruction disclosed by ultrasonography, computed tomography or endoscopic cholangiography; (2) presence of antimitochondrial antibody (AMA)/AMA-M2; (3) histopathologic evidence of non-suppurative cholangitis and destruction of small or medium-sized bile ducts on liver biopsy if absence of AMA. Exclusion criteria included prior treatment with UDCA, corticosteroids, azathioprine, methotrexate in the preceding 6 months or features suggestive of other coexistent liver diseases including chronic hepatitis B, C, alcoholic liver disease, autoimmune hepatitis, primary sclerosing cholangitis or Wilson’s disease. In the process of UDCA therapy, patients added corticosteroids or immunosuppressive agents would also be excluded. When diagnosed, all of the patients received UDCA (Dr. Falk Pharma GmbH, Freiburg, Germany) at the dose of 13-15 mg∙kg^-1∙day^-1 and were followed up at least for 2 years. Calcium (600 mg∙day^-1, qd), vitamin AD (5 000 IU, qd, every other month) and vitamin E (0.1 g, tid, every other month) were also supplied to all PBC patients. The informed consent in writing was obtained from each patient and the study protocol was conformed to the ethical guidelines of the 1975 Declaration of Helsinki and approved by the ethical committee of the Fourth Military Medical University.

Staging

Histological staging of PBC proposed by Ludwig was adopted in our study: stage 1, inflammation is localized within the portal space; stage 2, the inflammation extends beyond the portal triads; stage 3, fibrosis appears and there is a reduction of number of bile ducts; stage 4, characterized by frank cirrhosis. Since the different histological stages can co-exist in the same biopsy, the stage is assigned according to the most advanced histological stage by convention.

Clinical course of PBC was divided into four different stages [14,15]: stage 1, patients are both clinically and biochemically asymptomatic; stage 2, patients are clinically asymptomatic but with abnormal biochemistry; stage 3, patients are symptomatic and with abnormal biochemistry; stage 4, characterized by clinical cirrhosis. It is called “clinical stage” below. Although clinical stage doesn’t all correspond to histological stage in natural course of PBC patient, we defined clinical stages 1-2 and histological stages 1-2 as “early stage.”

Follow-up

At entry and every 3 months, clinical manifestation and physical examination were performed, and serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), ALP, γ-GT, bilirubin, cholesterol and prothrombin index were measured. Serum immunoglobulin M (IgM) concentrations were assessed at entry and every 6 months.

The scoring system for fatigue and pruritus were as following: grade 1, none; grade 2, mild; grade 3, moderate; grade 4, severe and grade 5, permanent or tough. For relationship between biochemical response and prognosis [16-18], Paris criteria [16] and Barcelona criteria [17] were used to assess biochemical response after 1-year therapy. Initial liver biopsy was available in 74 total patients and repeated liver biopsy was taken for 14 patients at the end of 2-year follow-up. Histological parameters such as portal inflammation, piecemeal necrosis, lobular necrosis, ductular proliferation, bridging fibrosis and cholestasis were graded on a scale of 0 (none), 1 (mild), 2 (moderate) and 3 (severe). Liver biopsy specimens were reviewed by two sophisticated pathologists independently.

Statistical analysis

All data were analyzed using the SPSS statistical package 13.0. Quantitative variables with a normal distribution were expressed as means±standard deviation, whereas those with a skewed distribution were expressed as medians (range). Two-sample t-test, One-way ANOVA of repeat measurement data and Wilcoxon signed rank test were used to analyze differences with respect to changes in laboratory values and clinical features from baseline to 2-year observation end-time. Comparisons between patients with biochemical response at one year were made using the Chi-square analysis, which was also used to compare the rate of biochemical response at different histological stages. Changes of histological feature were assessed by Mann-Whitney Test. Own control is adopted to compare anterior-posterior index of UDCA therapy. A two tailed P value<0.05 was considered to be statistically significant.

Results

Patients characteristics

Baseline characteristics of each stage were showed in Table 1. The study population comprised 67 patients (86.6% female) eventually, with a mean age of 51.4±8.98 years, who were followed up for a median of 2.3 (range 2.0-3.1) years. We rejected seven patients out of total 74 because three cases (4.05%) were lost for follow-up and four cases (5.41%) were added corticosteroids in the process of UDCA therapy. The manifestations of decompensated liver disease such as hemorrhage or ascites were in six patients (8.96%) when included. All subjects were performed a percutaneous liver biopsy before being enrolled into the study and only 14 (20.9%) patients received biopsy after 2-year therapy again. The majority of patients were at clinical stages 2-3 (67.2%) and histological stages 3-4 (79.1%).

In the total 67 patients evaluated, 10 patients were screened and then diagnosed for their family members had been diagnosed as PBC. Among them, 6 were at clinical stage 1 and another 4 at clinical stage 2. When diagnosed, the patients at stage 1 were around 40 years old, who were about 10 years younger than those at stages 2 and 3 (Table 1). The age of patients at stage 2 was almost the same as those at stage 3. The patients at stage 4 were about 7 years older than those at stages 2 and 3 (Table 1).

Effect of treatment on clinical variables

Before UDCA treatment, 43 and 35 PBC patients complained about fatigue (26 mild and moderate, 17 severe) and pruritus (23 mild and moderate, 12 severe) respectively. The extent of fatigue and pruritus was scored. Two years after UDCA treatment, the fatigue and pruritus was re-evaluated. During follow-up, the severity of fatigue and pruritus decreased significantly in patients taking UDCA for 2 years (Fig. 1A). To further clarify the effect of UDCA on symptoms, symptomatic patients were divided into 3 groups according to the extent of symptoms: mild, moderate and severe. It was clear that about 50%-60% patients with mild or moderate symptoms got alleviated with UDCA treatment, while more than 70% patients with severe symptoms remained unchanged by UDCA (Fig. 1B, C). These suggested UDCA treatment could attenuate fatigue and pruritus, especially in the patients with mild or moderate symptoms.

However, there was no statistic variation in other clinical characteristics such as skin pigmentation, splenomegaly and xanthoma (data not shown, P>0.05).

Effect of treatment on biochemical variables

The changes of biochemical variables pre- and post-treatment were shown in Table 2. For patients at clinical stages 2-4, the ALP and γ-GT levels of post-treatment were much lower than that of pre-treatment (P<0.05). Significant decrease was also seen in ALT and AST levels (P<0.05). However, the bilirubin and IgM levels didn’t change after 2-year treatment (P>0.05). There weren’t significant benefit on liver synthesis parameters such as albumin, cholesterol and prothrombin index (P>0.05).

The dynamic changes of ALP and γ-GT were further explored. ALP and γ-GT of patients at stage 1 remained in normal ranges during the 2-year treatment (Fig. 2). For patients at stages 2-4, ALP and γ-GT levels declined rapidly during the first 24 weeks and got significant improvement 2 years after treatment comparing to baseline values (Fig. 2). From 24 weeks after UDCA therapy, the ALP and γ-GT of patients at stage 2 fell into normal range. However, the ALP and γ-GT of patients at stages 3-4 were still above the upper limit of normal ranges even after 2-year treatment (Fig. 2). These suggested PBC patients at early stage would benefit much more from UDCA therapy than those at late stage.

Effect of treatment on histological characteristics

The distributions of histological stage before and after treatment were shown in Table 3 and changes of histological feature were shown in Table 4. For patients at stages 1 and 2, their state was almost stable during the 2-year therapy (Table 3). However, almost all the patients at stages 3 and 4 progressed to advanced stage (Table 3). These suggested that UDCA treatment could help to stop the progress of pathological changes in patients at early stage but not in patients at late stage.

The histological characteristics were further analyzed. It was found there was less lymphocyte infiltration in portal area as well as severer bridging fibrosis 2 years after UDCA treatment than that before treatment, no matter which stage the patient was at (Fig. 3). As shown in Table 4, the degree of bridging fibrosis had statistically aggravated (P<0.05) and the portal inflammatory infiltration lessened significantly after treatment than before (P<0.05). There was an alleviative tendency for piecemeal necrosis, lobular necrosis and ductular proliferation. However, the difference between pre-treatment and post-treatment was not significant (Table 4).

Biochemical response with Paris criteria and Barcelona criteria

The rates of biochemical response of PBC patients treated with UDCA were assessed by both Paris criteria and Barcelona criteria. As shown in Table 5, the biochemical response rate significantly decreased when clinical stage progressed according to both criteria. The patients at stage 2 achieved best biochemical response whereas those at stage 4 showed lowest response rate, indicating the importance to find and treat PBC patients at early stage. In addition, Barcelona criteria revealed higher biochemical response rate than Paris criteria (Table 5). For patients at stage 2, these two criteria matched each other very well. The difference rose in patients at late stage, especially in patients at stage 4.

Adverse events

Severe side-effects were not documented in any patients, and minor side effects, such as diarrhea and abdominal pain, were observed in three patients receiving UDCA. Symptoms above-mentioned needn’t to be treated because of their self-limitation in 2-3 days [19].

Discussion

In our study, we observed UDCA treatment on Chinese patients with PBC and this is the first long-term prospective study regarding Chinese patients. After 2-year follow-up, our data suggested that symptoms such as fatigue and pruritus were improved in some extent, which resembles domestic reports [20]. This benefit was seen in patients with mild or moderate symptom but not in those with severe fatigue or pruritus. Majority of patients who got better effects were almost at clinical stage 3 and histological stages 1-3 in our observation. Actually, most of the published trials relating to clinical manifestation remain controversial. Several randomized-controlled trails demonstrated UDCA could alleviate symptoms such as fatigue and pruritus [21,22]. More opposite results showed that no significant benefit was observed in improving symptoms [8-10]. The resources were mainly from western countries. Ours confirmed that UDCA did improve some symptoms but decided by baseline and severity. Disparity of lifestyle and medications, such as smoke, abortion or taking contraceptive agent [23], and genetic polymorphism of hepatobiliary transport proteins, such as multidrug resistance protein 2 [24], and nuclear receptors, such as farnesoid X receptor, peroxisome proliferation-activated receptor α [25] and pregnane X receptor [24], may be some probable factors to explain the difference in symptom improvement between western and Chinese patients. Anyway, for the baseline level of stage and degree of symptom correlate with the therapeutic effect, early detection is important.

With regard to the effect on biochemical parameters, nearly all the evidences support UDCA therapy [26]. We proved the similar conclusion. Patients with complete normalization of serum bilirubin, ALP, ALT and AST will have low risk to progress to cirrhosis [1]. Thus the aim of UDCA therapy is to provide the normalization of serum biochemical parameters. In our study, the favorable effects of UDCA on liver function tests, particularly a marked improvement of cholestasis parameters, mainly ALP and γ-GT, as well as other markers such as ALT and AST, have been observed the same as other researchers reported [17,26]. In our study, the levels of ALP and γ-GT at stage 4 are lower than those at stage 3. We consider that it might be due to the functional impairment of enzyme production or release when cirrhosis occurs. Although there were no improving effects on bilirubin and IgM in our statistic analysis, the levels of them appeared a tendency of descent in part of PBC patients at baseline stages 2-3. Serum bilirubin level was considered to be an independent predictor of prognosis in some studies [27,28]. More cases should be included in subsequent study to identify the therapeutic effect of UDCA on bilirubin and IgM in Chinese cohort. Although there were no significant benefits on liver synthesis markers such as albumin, cholesterol and prothrombin index, these parameters had not got worse obviously after 2 years.

Several long-term studies on natural history of PBC have shown that the median survival of PBC patients is 10-15 years, which is much poorer than that of an age- and sex-matched control population [2,29]. Without treatment, a randomized clinical trial demonstrated that histological progression was observed after 1 year in 41%, 43%, and 35% of the patients, and after 2 years in 62%, 62%, and 50% of the patients who were at stage 1, stage 2, and stage 3 when enrolled, respectively. Majority of patients with PBC will progress histologically within 2 years [30]. Thus whether UDCA could delay disease progression, especially histological progression is an effective criterion to assess curatives. Observation on change of histology had proceeded in our follow-up. Analysis of 14 paired liver biopsy revealed that a 2-year treatment reduces portal inflammatory lesions, ameliorates ductular proliferation, and delays the histological progression especially in patients at early stage. However, UDCA is not capable of stopping fibrosis progression. The presence of cirrhosis such as pseudolobule and fiber septa still appears in half patients of baseline stage 3 after treatment. In many randomized trials UDCA has been proved not only to delay progression [6] but also to prevent liver fibrosis [7]. Research by Poupon and his colleagues showed that UDCA therapy was associated with a 5-fold lower progression rate from early stage disease to extensive fibrosis or cirrhosis (7% per year under UDCA vs. 34% per year under placebo) [7]. The discrepancy between our finding and those oversea trials may probably be due to the factor that the rate of progression of PBC is very slow, and our limited period of 2 years between biopsies was too short to find such differences. For the amounts of paired liver biopsies were few, result of statistic analysis may be not exact enough. We still require a longer period of follow-up in the subsequent research.

Biochemical response rates to UDCA among patients at clinical stages 2-4 were unequal in our study. Patients at early stage could gain the best response using both Paris and Barcelona criteria. It may relate to lower baseline of ALP, AST, bilirubin level and is easier to be normalized. Good response could also be achieved in patients asymptomatic [31]. Resembled results can be seen in a 9-year follow-up research, which concluded that patients who remained non-fatigued had a remarkably good outcome [9]. Relationship between long-term prognosis and biochemical response to UDCA treatment is proved to be intimate [25,32]. A long-term (median of more than 7 years) study by Corpechot and colleagues demonstrated that the probability of survival free of liver transplantation is significantly higher in those experiencing a good biochemical response [17]. Thus, judgment to favorable biochemical response will help us to build the confidence on course of treatment.

In summary, our study provided new information about UDCA therapy in Chinese cohort with PBC and confirmed the importance of early treatment. When treated in early stage, patients in long-term administration could often gain satisfactory results not only on symptom and biochemical response but also on histology. Late histological stage, bad biochemical response and severe symptom may be factors of poor prognosis for UDCA therapy. The disparity between our results and those reported by western groups may possibly be explained as difference in patient population, geographic variation, genetic makeup [33,34] and environmental exposure [35,36], which is waiting to be confirmed and kept on researching. Our limitations was that we didn’t take long enough time for follow-up and include more cases for observation yet. Thus, whether Chinese patients with PBC are indeed benefited from long-term UDCA should still need further and larger-sample multi-center researches.

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