Prediction of short-term survival with an application in primary biliary cirrhosis

Prognostic Models for Survival in Patients with Stable Cirrhosis: A Multicenter Cohort Study

BACKGROUND

Two models are mostly used to predict survival in cirrhosis: the Child-Pugh score (CP score) and the model for end-stage liver disease score (MELD score).

AIMS

The aim of this study is to evaluate the CP score and the MELD score for short- and long-term prognosis in cirrhosis, as well as CP-creatinine score, MELD-Na score, and UKELD score.

METHODS

One thousand and forty-seven patients from five referral centers were included: men/women: 620/427, median age: 58 years (IQR 48-66), median follow-up: 33 months (IQR 12-74), CP (A/B/C): 493/357/147, CP score: 7 (IQR 5-9), MELD score: 12 (IQR 9-16). The performance of each score was evaluated by the Cox hazard model in terms of their: discrimination ability (C-index and Somer's D) and calibration (3, 12 months). Internal validation was done with bootstrapping (100 samples).

RESULTS

Three hundred and fifty-two patients (33.6%) died. All scores were significantly associated with overall mortality, when assessed by univariate Cox analysis. CP-creatinine score performed significantly better than all other scores [bootstrap C-index 0.672, 95% CI 0.642-0.703, bootstrap Somer's D 0.344 (0.285-0.401)], apart from CP score, which showed similar performance. Inclusion in the multivariable Cox model of age together with CP-creatinine score improved the discriminative ability of the model [bootstrap C-index (95% CI) 0.700 (0.661-0.740)]. In terms of calibration, CP-creatinine score was the best for both 3- and 12-month survival in the total population.

CONCLUSIONS

CP score and CP-creatinine score have better prognostic value compared to MELD score, MELD-Na score, and UKELD score for predicting short- and long-term mortality in patients with stable cirrhosis.

The value of daily platelet counts for predicting dengue shock syndrome: Results from a prospective observational study of 2301 Vietnamese children with dengue

BACKGROUND

Dengue is the most important mosquito-borne viral infection to affect humans. Although it usually manifests as a self-limited febrile illness, complications may occur as the fever subsides. A systemic vascular leak syndrome that sometimes progresses to life-threatening hypovolaemic shock is the most serious complication seen in children, typically accompanied by haemoconcentration and thrombocytopenia. Robust evidence on risk factors, especially features present early in the illness course, for progression to dengue shock syndrome (DSS) is lacking. Moreover, the potential value of incorporating serial haematocrit and platelet measurements in prediction models has never been assessed.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed data from a prospective observational study of Vietnamese children aged 5-15 years admitted with clinically suspected dengue to the Hospital for Tropical Diseases in Ho Chi Minh City between 2001 and 2009. The analysis population comprised all children with laboratory-confirmed dengue enrolled between days 1-4 of illness. Logistic regression was the main statistical model for all univariate and multivariable analyses. The prognostic value of daily haematocrit levels and platelet counts were assessed using graphs and separate regression models fitted on each day of illness. Among the 2301 children included in the analysis, 143 (6%) progressed to DSS. Significant baseline risk factors for DSS included a history of vomiting, higher temperature, a palpable liver, and a lower platelet count. Prediction models that included serial daily platelet counts demonstrated better ability to discriminate patients who developed DSS from others, than models based on enrolment information only. However inclusion of daily haematocrit values did not improve prediction of DSS.

CONCLUSIONS/SIGNIFICANCE

Daily monitoring of platelet counts is important to help identify patients at high risk of DSS. Development of dynamic prediction models that incorporate signs, symptoms, and daily laboratory measurements, could improve DSS prediction and thereby reduce the burden on health services in endemic areas.

Biochemical criteria at 1 year are not robust indicators of response to ursodeoxycholic acid in early primary biliary cirrhosis: results from a 29-year cohort study

BACKGROUND

In primary biliary cirrhosis (PBC), biochemical criteria at 1 year are considered surrogates of response to ursodeoxycholic acid (UDCA). However, due to the slow natural history of PBC, evaluation at 1 year may be suboptimal to assess the therapeutic response, particularly in early disease.

AIM

To determine whether evaluation of biochemical criteria at 1 year is a reliable surrogate of UDCA response in early PBC.

METHODS

We analysed the prospectively collected data of 215 patients (untreated = 129; UDCA-treated = 86) with early PBC (normal baseline bilirubin/albumin) and a median follow-up of 8 years (range: 1-29.1). The 1-year attainment rates of the Barcelona, Paris-I, Paris-II and Toronto definitions, and their predictive relevance for a poor outcome (death, transplantation, complications of cirrhosis), were assessed either as a result of UDCA or no treatment. Independent associations with attaining each UDCA response definition were identified by multivariate analysis.

RESULTS

Untreated patients displayed 1-year biochemical features compatible with 'treatment response' at rates (Barcelona: 36.4%, Paris-I: 66.7%, Toronto: 59.7%, Paris-II: 40.3%) similar to those obtained under UDCA. Depending on the definition, baseline ALP≤3xULN (OR: 4.80-35.90), AST≤2xULN (OR: 5.63-9.34) and early histological stage (OR: 3.67-3.87) were the stronger predictors for attaining the criteria. UDCA treatment was associated with attaining Barcelona (OR = 2.16) and Paris-II (OR = 2.84), but not Paris-I, and not Toronto definition when excluding late histological cases. Paris-I criteria were significantly predictive of long-term outcomes (HR = 2.83) in untreated patients.

CONCLUSIONS

In early PBC, biochemical criteria at 1 year reflect severity of the disease rather than the therapeutic response to UDCA.

Ursodeoxycholic acid improves bilirubin but not albumin in primary biliary cirrhosis: further evidence for nonefficacy

Background/Aim. In randomised controlled trials (RCTs) of ursodeoxycholic acid (UDCA), although serum bilirubin is frequently reduced, its effect on disease progression and mortality is unclear. As serum albumin is an established independent prognostic marker, one might expect less deterioration of serum albumin values in a UDCA-treated group. We therefore modelled the typical evolution of serum bilirubin and albumin levels over time in UDCA-untreated patients and compared it with the observed levels in UDCA RCTs. Methods. Multilevel modelling was used to relate the evolution of serum albumin to serum bilirubin and time since patient referral. For each considered RCT, the derived model was used to predict the relationship between final mean serum albumin and bilirubin concentration, adjusted for mean serum albumin at referral and followup duration. Results. Five RCTs were eligible in terms of available data, of which two had long followup. In all trials, serum albumin did not significantly differ between UDCA- and placebo-treated patients, despite the UDCA effect on serum bilirubin. Therefore, there is no evidence over time for changes or maintenance of albumin levels for UDCA-treated patients above the levels predicted for placebo-treated patients. Conclusions. Our findings suggest that UDCA does not alter serum albumin in a way that is consistent with its effect on serum bilirubin. Therefore, reductions in serum bilirubin of UDCA-treated PBC do not parallel another validated and independent prognostic marker, further questioning the validity of serum bilirubin reduction with UDCA as a surrogate therapeutic marker.

Predicting the advent of ascites and other complications in primary biliary cirrhosis: a staged model approach

BACKGROUND

Current survival models for primary biliary cirrhosis have limited precision for medium and long-term survival. Aim To describe a prognostic model for the advent of complications in primary biliary cirrhosis as the first approach to a staged prognostic model.

METHODS

From an established database of 289 consecutive primary biliary cirrhosis patients referred to Royal Free Hospital over 12 years (mean follow-up of 4.1 years), baseline characteristics at referral were evaluated by Cox-proportional hazards regression modelling.

RESULTS

The following complications occurred de novo: 85 ascites/peripheral oedema, 40 oesophagogastric varices, 63 encephalopathy, 29 spontaneous bacterial peritonitis and/or septicaemia, 59 symptomatic urinary tract infections. Age, albumin, log(10)(bilirubin), presence of ascites at referral, variceal bleeding within 6 weeks before referral, detection of oesophagogastric varices at or before referral were significant at multivariate analysis with different combinations and coefficients for each complication. The model for predicting ascites and/or peripheral oedema best fitted the observed data (ROC = 0.7682, S.E. = 0.0385).

CONCLUSIONS

The known prognostic factors in primary biliary cirrhosis also model the advent of complications. In view of the prognostic importance of ascites and its more robust statistical model, ascites and/or peripheral oedema could represent, following validation, the most suitable staged model in primary biliary cirrhosis to improve precision in survival modelling.

Variceal bleeding in primary biliary cirrhosis patients: a subgroup with improved prognosis and a model to predict survival after first bleeding

BACKGROUND

Varices are a late complication in primary biliary cirrhosis (PBC). However, patients without clinical jaundice do bleed from varices; whether their prognosis differs is unknown.

AIM

Evaluate PBC patients, particularly those with bilirubin <or=34 micromol/l at the time of bleeding.

PATIENTS/RESULTS

One hundred and two variceal bleeders were present (median, follow-up 20.5 months, range 0-180), who at diagnosis had: pruritus (51%), fatigue (32%) and 23 (22.5%) variceal bleeding. Histologically advanced disease was present in 96 of 100 patients (stage 3: 14 and stage 4: 82); 83 died, 24 within 6 weeks of first bleeding. At the time of bleeding, 26 patients had bilirubin <or=34 micromol/l. In this group, 24 patients were stage 4, in 13 bleeding was the first presentation of PBC and they were older (59.4 vs. 55.4 years, P=0.09), had lower alkaline phosphatase (491.5 vs. 510, P=0.03) but similar albumin values, surviving a median 61 versus 12 months, compared with the 76 patients with bilirubin >34 micromol/l (P=0.001, log rank test). Hazard ratios (95% confidence intervals) for independent predictors of mortality after bleeding were: age 1.02 (1-1.05), log10 bilirubin 4.64 (2.56-8.41), ascites 2.13 (1.29-3.51) and hepatic encephalopathy 2.72 (1.56-4.74).

CONCLUSION

Variceal bleeding complicates histologically advanced PBC. A distinct subgroup with near normal bilirubin and lower alkaline phosphatase first presents with variceal bleeding in 50% of cases and has a better prognosis than jaundiced PBC variceal bleeders.

Clinical features and management of primary biliary cirrhosis

Primary biliary cirrhosis (PBC), which is characterized by progressive destruction of intrahepatic bile ducts, is not a rare disease since both prevalence and incidence are increasing during the last years mainly due to the improvement of case finding strategies. The prognosis of the disease has improved due to both the recognition of earlier and indolent cases, and to the wide use of ursodeoxycholic acid (UDCA). New indicators of prognosis are available that will be useful especially for the growing number of patients with less severe disease. Most patients are asymptomatic at presentation. Pruritus may represent the most distressing symptom and, when UDCA is ineffective, cholestyramine represents the mainstay of treatment. Complications of long-standing cholestasis may be clinically relevant only in very advanced stages. Available data on the effects of UDCA on clinically relevant end points clearly indicate that the drug is able to slow but not to halt the progression of the disease while, in advanced stages, the only therapeutic option remains liver transplantation.

An Economic Evaluation of Pediatric Small Bowel Transplantation in the United Kingdom

BACKGROUND

Small bowel transplantation (SBTx) offers an alternative to parenteral nutrition (PN) for the treatment of chronic intestinal failure in children: this study estimated its cost-effectiveness in the early phase of a U.K. program.

METHODS

Children assessed for SBTx were categorized as: 1) requiring SBTx following PN-related complications (n=23), 2) stable at home not requiring SBTx (n=24), and 3) terminally ill and unsuitable for SBTx (n=6). Costs were estimated from detailed resource-use data. Two comparisons were used for effectiveness: actual survival following transplantation (n=14) compared to: 1) estimated survival without transplantation using a prognostic model, and 2) the waiting list experiences of all patients listed for SBTx (n=23).

RESULTS

Mean costs up to 30 months were pounds sterling 207,000 for those transplanted or on the waiting list, pounds sterling 159,000 for those stable on home PN, and pounds sterling 56,000 for those terminally ill. The prognostic model estimated a mean survival gain from transplantation of 0.12 years over 30 months, and suggested that transplantation was cost-saving. The second approach suggested that transplantation reduced survival by 0.24 years at an additional cost of pounds sterling 131,000.

CONCLUSIONS

Firm conclusions on cost-effectiveness of SBTx are not possible given the two different estimates. The prognostic model approach (suggesting that pediatric SBTx may provide a small survival benefit at a small reduction in costs) should be less subject to bias, but the model requires external validation. Meanwhile, children at risk of fatal PN-complications should be given the opportunity to receive a SBTx only within a continuing formal assessment of the technology.

Survival following the development of ascites and/or peripheral oedema in primary biliary cirrhosis: a staged prognostic model

OBJECTIVE

Current prognostic models in primary biliary cirrhosis (PBC) have low precision, partly due to the restricted inclusion criteria of some cohorts used for modelling but also because of the prolonged natural course of the disease. It is hypothesized that better precision could be achieved with a staged model, using ascites or peripheral oedema as a new starting-point for prediction.

MATERIAL AND METHODS

The study was based on an established database of 289 consecutive patients, followed between 1977 and 1998. Stepwise Cox regression was used to construct a staged model based on 143 patients who first developed ascites (n=111) or peripheral oedema (n=32) at entry or during subsequent follow-up. The model was compared with published models using graphical methods and receiver operating characteristics (ROCs).

RESULTS

Mean time from clinical diagnosis of ascites or peripheral oedema to death was 3.1 years. The following variables had independent prognostic significance: log10(bilirubin) (p<0.001), albumin (p<0.001), age (p<0.001) and history of encephalopathy (p<0.001). Goodness of fit showed that the survival probabilities predicted by the Ascites Stage Model fitted well with the observed data. The Ascites Stage Model (ROC 0.8324 (SE 0.0348)) was a better predictor of survival than the Mayo long-term model (ROC 0.7833 (SE 0.0397)), the Mayo Repeated Patient Visits Model (ROC 0.7779 (SE 0.0399)) and the Royal Free PBC Prognostic Model (ROC 0.7785 (SE 0.0396)).

CONCLUSIONS

The Ascites Stage Model gives a better survival estimate for PBC patients once they have developed ascites or peripheral oedema compared with the current models, and demonstrates an advantage of staged models in diseases with a prolonged natural history.

Long-term ursodeoxycholic acid therapy for primary biliary cirrhosis: a follow-up to 12 years

BACKGROUND

It is uncertain whether ursodeoxycholic acid therapy slows down the progression of primary biliary cirrhosis, according to two meta-analyses. However, the randomized trials evaluated had only a median of 24 months of follow-up.

AIM

To evaluate long-term ursodeoxycholic acid therapy in primary biliary cirrhosis.

METHODS

We evaluated 209 consecutive primary biliary cirrhosis patients, 69 compliant with ursodeoxycholic acid and 140 untreated [mean follow-up 5.79 (s.d. = 4.73) and 4.87 (s.d. = 5.21) years, respectively] with onset of all complications documented. Comparison was made following adjustment for baseline differences according to Cox modelling, Mayo and Royal Free prognostic models.

RESULTS

Bilirubin and alkaline phosphatase concentrations improved with ursodeoxycholic acid (at 36 months, P = 0.007 and 0.018, respectively). Unadjusted Kaplan-Meier analysis showed benefit (P = 0.028), as 44 (31%) untreated and 15 (22%) ursodeoxycholic acid patients died or had liver transplantation. However, there was no difference when adjusted by Cox modelling (P = 0.267), Mayo (P = 0.698) and Royal Free models (P = 0.559). New pruritus or fatigue or other complications were not different, either before or after adjustment for baseline characteristics.

CONCLUSIONS

Long-term ursodeoxycholic acid therapy did not alter disease progression in primary biliary cirrhosis patients despite a significant improvement in serum bilirubin and alkaline phosphatase consistent with, and similar to, those seen in ursodeoxycholic acid cohorts in randomized trials.

Midterm cost-effectiveness of the liver transplantation program of England and Wales for three disease groups

Liver transplantation has never been the subject of a randomized controlled trial, and there remains uncertainty about the magnitude of benefit and cost-effectiveness for specific patient groups. This article reports the results of an economic evaluation of adult liver transplantation in England and Wales. Patients placed on the waiting list for a liver transplant were observed over 27 months. The costs and health benefits of a comparison group, representing experience in the absence of liver transplantation, were estimated using a combination of observed data from patients waiting for a transplant and published prognostic models. The analysis focuses on three disease groups, for each of which prognostic models were available: primary biliary cirrhosis (PBC), alcoholic liver disease (ALD), and primary sclerosing cholangitis (PSC). A higher proportion of patients with ALD were assessed for a transplant but not placed on the waiting list. The estimated gain in quality-adjusted life-years from transplantation was positive for each of the disease groups. The mean incremental cost per quality-adjusted life-year (95% bootstrap confidence intervals) from time of listing to 27 months for patients with PBC, ALD, and PSC are pound 29,000 (pounds 1,000 to pounds 59,000), pounds 48,000 (pounds 12,000 to pounds 83,000) and pounds 21,000 (-pounds 23,000 to pounds 60,000), respectively. In conclusion, liver transplantation increases the survival and health-related quality of life of patients with each of three end-stage liver diseases. However, the extent of this increase differs between different disease groups. Cost-effectiveness estimates were poorer for patients with ALD over the 27-month period than for patients with PBC or PSC. This in part reflects the costs of the higher number of ALD patients assessed for each transplant.

Short-term risk of disease progression in HIV-1-infected children receiving no antiretroviral therapy or zidovudine monotherapy: a meta-analysis

BACKGROUND

Data on the short-term risk of disease progression in HIV-1-infected children are needed to address the question of when to begin combination antiretroviral therapy. We estimated 12-month risks of progression to AIDS and death, by age and most recent measurement of CD4 T-cell percentage (CD4%) or viral load, in children receiving no antiretroviral therapy or zidovudine monotherapy only.

METHODS

We undertook a meta-analysis of individual longitudinal data for 3941 children from eight cohort studies and nine randomised trials in Europe and the USA. Estimates of risk were derived from parametric survival models.

FINDINGS

997 AIDS-defining events were recorded over 7297 person-years of follow-up in the analysis of CD4%, and 284 events over 2282 person-years in the viral load analysis, corresponding to 568 deaths (9087 person-years) and 129 deaths (2816 person-years), respectively. In children older than 2 years, risk of death increased sharply when CD4% was less than about 10%, or 15% for risk of AIDS, with a low and fairly stable risk at greater CD4%. Children younger than 2 years had worse outlook than older children with the same CD4%. Risk of progression increased when viral load exceeded about 10(5) copies per mL, although this association was more gradual compared with CD4%. Both markers had independent predictive value for disease progression; CD4% was the stronger predictor.

INTERPRETATION

This information is important for paediatricians making decisions, and for researchers designing trials, about when to initiate or restart antiretroviral therapy.

Preventative therapy in primary biliary cirrhosis

Because the etiology of PBC is still unknown, therapies remain empirical. Moreover, no contributions on preventative therapy supported by evidence-based medicine have been published to date. However, there are at least two groups of subjects who might benefit from preventative therapy: (1) subjects with normal liver enzymes who are found AMA-positive during autoantibody screening and (2) subjects transplanted for PBC with no histologic or biochemical signs of disease recurrence. The key questions are whether any therapy should be proposed to these subjects, since the natural history of the disease is very long, and what kind of treatment should be prescribed. UDCA is a well-tolerated, definitely "physiologic" treatment, but it is expensive and two recent meta-analyses question its benefit on survival. Current theory considers PBC an autoimmune disease, with a genetic predisposition, possibly triggered by an infectious agent or xenobiotic. If this is so, gene therapies might be the most promising future preventative therapies. For the time being, however, the only practical preventative management is in regards to the complications of PBC, namely osteopenia and portal hypertension.

Liver transplantation in the UK

INTRODUCTION

This paper provides a review of the practice of liver transplantation with the main emphasis on UK practice and indications for transplantation.

REFERRAL AND ASSESSMENT

This section reviews the process of referral and assessment of patients with liver disease with reference to UK practice.

DONOR ORGANS

The practice of brainstem death and cadaveric organ donation is peculiar to individual countries and rates of donation and potential areas of improvement are addressed.

OPERATIVE TECHNIQUE

The technical innovations that have led to liver transplantation becoming a semi-elective procedure are reviewed. Specific emphasis is made to the role of liver reduction and splitting and living related liver transplantation and how this impacts on UK practice are reviewed. The complications of liver transplan-tation are also reviewed with reference to our own unit. Immunosuppression:The evolution of immunosuppression and its impact on liver transplantation are reviewed with some reference to future protocols.

RETRANSPLANTATION

The role of retransplantation is reviewed.

OUTCOME AND SURVIVAL

The results of liver transplantation are reviewed with specific emphasis on our own experience.

FUTURE

The future of liver transplantation is addressed.

Time-dependent Cox regression model is superior in prediction of prognosis in primary sclerosing cholangitis

More precise prognostic models are needed for prediction of survival in patients with primary sclerosing cholangitis (PSC), particularly for the selection of candidates for liver transplantation. The aim of this study was to develop a time-dependent prognostic model for the calculation of updated short-term survival probability in PSC. Consecutive clinical and laboratory follow-up data from the time of diagnosis were collected from the files of 330 PSC patients from 5 European centers, followed for a median of 8.4 years since diagnosis. Time-fixed and time-dependent Cox regression analyses, as well as the additive regression model, were applied. The reliability of the models was tested by a cross-validation procedure. Bilirubin (on a logarithmic scale), albumin, and age at diagnosis of PSC were identified as independent prognostic factors in multivariate analysis of both the time-fixed and the time-dependent Cox regression models. The importance of bilirubin was more pronounced in the time-dependent model (hazard ratio [HR], 2.84) than in the time-fixed analysis (hazard ratio, 1.51). The additive regression model indicated that once the patients survive beyond the first 5 years, the impact on prognosis of albumin at diagnosis ceases. The time-dependent prognostic model was superior to the time-fixed variant in assigning low 1-year survival probabilities to patients that actually survived less than 1 year. In conclusion, a time-dependent Cox regression model has the potential to estimate a more precise short-term prognosis in PSC compared with the traditional time-fixed models.

Liver transplantation in the UK

INTRODUCTION

This paper provides a review of the practice of liver transplantation with the main emphasis on UK practice and indications for transplantation.

REFERRAL AND ASSESSMENT

This section reviews the process of referral and assessment of patients with liver disease with reference to UK practice.

DONOR ORGANS

The practice of brainstem death and cadaveric organ donation is peculiar to individual countries and rates of donation and potential areas of improvement are addressed.

OPERATIVE TECHNIQUE

The technical innovations that have led to liver transplantation becoming a semi-elective procedure are reviewed. Specific emphasis is made to the role of liver reduction and splitting and living related liver transplantation and how this impacts on UK practice are reviewed. The complications of liver transplan-tation are also reviewed with reference to our own unit. Immunosuppression:The evolution of immunosuppression and its impact on liver transplantation are reviewed with some reference to future protocols.

RETRANSPLANTATION

The role of retransplantation is reviewed.

OUTCOME AND SURVIVAL

The results of liver transplantation are reviewed with specific emphasis on our own experience.

FUTURE

The future of liver transplantation is addressed.

A simulation modelling approach to evaluating alternative policies for the management of the waiting list for liver transplantation

A shortage of donor liver grafts unfortunately results in approximately 10% of patients dying whilst listed for a liver transplant in Europe and the United States. Thus it is imperative that all available organs are used as efficiently as possible. This paper reports upon the application of a simulation modelling approach to assess the impact of several alternative allocation policies upon the cost effectiveness of this technology at one liver transplant centre in the UK. The impact of changes in allocation criteria on the estimated net life expectancy, average net costs and overall cost effectiveness of the transplantation programme were evaluated. The incremental cost effectiveness ratio (ICER) for the base case allocation policy, based upon the time spent on the waiting list (i.e., longest wait first) was 11,557 pounds sterling at 1999 prices. The ICERs associated with an allocation policy based upon age (lowest age first), and an allocation policy based upon the severity of the pre-transplant condition of the patient (with most severely ill patients given a lower priority) were lower than the base case at 10,424 pounds sterling and 9,077 pounds sterling, respectively. The results of this modelling study suggest that the overall cost effectiveness of the liver transplantation programme could be improved if the current allocation policy were modified to give more weight to the age of the patient and the reduced chances of success of the most severely ill patients.

Randomised controlled trials of ursodeoxycholic-acid therapy for primary biliary cirrhosis: a meta-analysis

BACKGROUND

Ursodeoxycholic acid (UDCA) is the only approved treatment for primary biliary cirrhosis, but its effect on disease progression and survival is uncertain. The aim of this study was to clarify the efficacy of UDCA in primary biliary cirrhosis.

METHODS

A systematic review, including the use of meta-analysis, was done for the randomised and switch-over phases of trials comparing UDCA with placebo, obtained from Medline and Embase databases, and from manual searches derived from review articles and abstracts of major international meetings. All trials had more than a mean of 6 months' follow-up and only included patients with primary biliary cirrhosis (PBC) according to established diagnostic criteria.

FINDINGS

17 relevant articles were identified: 11 randomised controlled trials, including 1272 patients, and six reports of the switch-over phases. UCDA had a favourable effect on liver biochemistry in most of the studies but not on symptoms or the progression of histological stage; two studies did not assess survival, liver transplantation, or complications of liver disease. Meta-analysis showed no difference between UDCA and placebo in the incidence of death (odds ratio 1.21, 95% CI 0.71-2.04), liver related death (0.72, 0.22-2.32), liver transplantation (1.27, 0.78-2.07), death or liver transplantation (1.26, 0.87-1.82), and in the development of complications of liver disease (1.11, 0.64-1.92). With the primary end point defined by the authors (a combined end point in three studies, and death or liver transplantation in the others) an odds ratio of 1.53 (0.97-2.42) was obtained. Assessment of the switch-over phases, during which there was a longer follow-up, did not change the results of the meta-analysis.

INTERPRETATION

Published randomised controlled trials of UDCA do not show evidence of therapeutic benefit in PBC and its use as standard therapy needs to be re-examined.

Optimal timing of liver transplantation for patients with primary biliary cirrhosis: use of prognostic modelling

BACKGROUND/AIMS

Liver transplantation remains the only definitive treatment for patients with end-stage primary biliary cirrhosis, although the optimal timing of the procedure remains uncertain. The aim of the study was to use prognostic modelling to determine the optimal timing of transplantation for patients with primary biliary cirrhosis.

METHODS

A prognostic model for predicting the survival of patients after transplantation was generated using the Cox regression model with data from 312 patients transplanted for primary biliary cirrhosis at the Queen Elizabeth Hospital, Birmingham. The prognosis after transplantation was compared to that without transplantation (using a previously published prognostic index for non-transplantation) both in these patients and in 98 non-transplanted primary biliary cirrhosis patients dying from the liver disease, in order to establish at what stage the prognosis with transplantation was better than without transplantation.

RESULTS

The prognostic index for transplantation included the following significant prognostic variables: serum bilirubin, serum albumin, age, year of transplantation, and the presence of ascites or treatment with diuretics. Comparison of prognosis with and without transplantation showed that the predicted gain in survival after transplantation becomes increasingly positive when the 6-month survival probability in the absence of transplantation falls below 0.85. In the non-transplanted patients this occurs on average about 8 months before death.

CONCLUSIONS

Comparison of the prognosis with and without transplantation provides a rational method for determining the optimum timing of the procedure which occurs approximately when the predicted 6-month survival probability without transplantation falls below 0.85.

Practical problems in fitting a proportional hazards model to data with updated measurements of the covariates

We review and discuss the practical problems encountered when analysing the effect on survival of covariates which are measured repeatedly over time. Specific issues arise over and above those met with the standard proportional hazards model and concern all stages of data preparation, data analysis and interpretation of the results. Data from a randomized clinical trial of patients with primary biliary cirrhosis, on whom several measurements were taken at regular intervals after entry, are presented as an illustration.