Chronic hepatitis B: treatment alert

A qualitative exploration of enablers for hepatitis B clinical management among ethnic Chinese in Australia

An estimated 18% of people living with chronic hepatitis B (CHB) in Australia were born in China. While guideline-based care, including regular clinical monitoring and timely treatment, prevent CHB-related cirrhosis, cancer and deaths, over three-quarters of people with CHB do not receive guideline-based care in Australia. This qualitative study aimed to identify enablers to engagement in CHB clinical management among ethnic Chinese people attending specialist care. Participants self-identified as of Chinese ethnicity and who attended specialist care for CHB clinical management were interviewed in Melbourne in 2019 (n = 30). Semi-structured interviews covered experiences of diagnosis and engagement in clinical management services, and advice for people living with CHB. Interviews were recorded with consent; data were transcribed verbatim and thematically analysed. Receiving clear information about the availability of treatment and/or the necessity of long-term clinical management were the main enablers for participants to engage in CHB clinical management. Additional enablers identified to maintain regular clinical monitoring included understanding CHB increases risks of cirrhosis and liver cancer, using viral load indicators to visualize disease status in patient-doctor communication; expectations from family, peer group and medical professionals; use of a patient recall system; availability of interpreters or multilingual doctors; and largely subsidized healthcare services. In conclusion, to support people attending clinical management for CHB, a holistic response from community, healthcare providers and the public health sector is required. There are needs for public health programmes directed to communicate (i) CHB-related complications; (ii) availability of effective and cheap treatment; and that (iii) long-term engagement with clinical management and its benefits.

Detection of hepatitis B virus genotypic resistance mutations by coamplification at lower denaturation temperature-PCR coupled with sanger sequencing

Mutations in the reverse transcriptase (rt) region of the DNA polymerase gene are the primary cause of hepatitis B virus (HBV) drug resistance. In this study, we established a novel method that couples coamplification at lower denaturation temperature (COLD)-PCR and Sanger sequencing, and we applied it to the detection of known and unknown HBV mutations. Primers were designed based on the common mutations in the HBV rt sequence at positions 180 to 215. The critical denaturation temperature (Tc) was established as a denaturing temperature for both fast and full COLD-PCR procedures. For single mutations, when a melting temperature (Tm)-reducing mutation occurred (e.g., C-G → T-A), the sensitivities of fast and full COLD-PCR for mutant detection were 1% and 2%, respectively; when the mutation caused no change in Tm (e.g., C-G → G-C) or raised Tm (e.g., T-A → C-G), only full COLD-PCR improved the sensitivity for mutant detection (2%). For combination mutations, the sensitivities of both full and fast COLD-PCR were increased to 0.5%. The limits of detection for fast and full COLD-PCR were 50 IU/ml and 100 IU/ml, respectively. In 30 chronic hepatitis B (CHB) cases, no mutations were detected by conventional PCR, whereas 18 mutations were successfully detected by COLD-PCR, including low-prevalence mutations (<10%), as confirmed by ultradeep pyrosequencing. In conclusion, COLD-PCR provides a highly sensitive, simple, inexpensive, and practical tool for significantly improving amplification efficacy and detecting low-level mutations in clinical CHB cases.

Seroconversion of hepatitis B envelope antigen (HBeAg) by entecavir in a child with chronic hepatitis B

Hepatitis B virus (HBV) infection is a worldwide health problem. Consensus guidelines for the treatment of chronic HBV in children have not been established, and indications for antiviral therapy in adults with chronic HBV infection may not be applicable to children. The medications that are Food and Drug Administration approved for the treatment of children with HBV include interferon (IFN)-alpha and lamivudine. Nondetectable serum HBV deoxyribonucleic acid, Hepatitis B envelope antigen (HBeAg) loss, and HBeAg seroconversion following 1 year duration of entecavir treatment. A review of the literature of entecavir treatment of chronic hepatitis B in children is also provided.

Medical management of chronic liver diseases in children (part I): focus on curable or potentially curable diseases

The management of children with chronic liver disease (CLD) mandates a multidisciplinary approach. CLDs can be classified into 'potentially' curable, treatable non-curable, and end-stage diseases. Goals pertaining to the management of CLDs can be divided into prevention or minimization of progressive liver damage in curable CLD by treating the primary cause; prevention or control of complications in treatable CLD; and prediction of the outcome in end-stage CLD in order to deliver definitive therapy by surgical procedures, including liver transplantation. Curative, specific therapies aimed at the primary causes of CLDs are, if possible, best considered by a pediatric hepatologist. Medical management of CLDs in children will be reviewed in two parts, with part I (this article) specifically focusing on 'potentially' curable CLDs. Dietary modification is the cornerstone of management for galactosemia, hereditary fructose intolerance, and certain glycogen storage diseases, as well as non-alcoholic steatohepatitis. It is also essential in tyrosinemia, in addition to nitisinone [2-(nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione] therapy, as well as in Wilson disease along with copper-chelating agents such as D-penicillamine, triethylenetetramine dihydrochloride, and ammonium tetrathiomolybdate. Zinc and antioxidants are adjuvant drugs in Wilson disease. New advances in chronic viral hepatitis have been made with the advent of oral antivirals. In children, currently available drugs for the treatment of chronic hepatitis B virus infection are standard interferon (IFN)-α-2, pegylated IFN-α-2 (PG-IFN), and lamivudine. In adults, adefovir and entecavir have also been licensed, whereas telbivudine, emtricitabine, tenofovir disoproxil fumarate, clevudine, and thymosin α-1 are currently undergoing clinical testing. For chronic hepatitis C virus infection, the most accepted treatment is PG-IFN plus ribavirin. Corticosteroids, with or without azathioprine, remain the basic strategy for inducing remission in autoimmune hepatitis. Ciclosporin (cyclosporine) and other immune suppressants may be used for patients who do not achieve remission, or who have significant side effects, with corticosteroid/azathioprine therapy. The above therapies can prevent, or at least minimize, progression of liver damage, particularly if started early, leading to an almost normal quality of life in affected children.

Viral hepatitis B in children: clinical characteristics and antiviral treatment

Chronic hepatitis B is a common and frequent disease occurring in children in China. Chronic hepatitis B virus infection during childhood may cause serious clinical consequences. Reasonable treatment is extremely important for children with therapeutic indications. However, there are many challenges in the treatment of chronic hepatitis B in children, such as treatment indications and the choice of antiviral therapy. This paper describes the natural history of HBV infection in children, indications for antiviral therapy, goals of antiviral treatment, and choice of antiviral drugs.

Evaluation of current treatment recommendations for chronic hepatitis B: a 2011 update

BACKGROUND AND AIM

Guidelines for the treatment of chronic hepatitis B have been recently updated in the 2009 European Association for the Study of the Liver consensus statement, the 2008 US Panel, the 2008 Asian-Pacific consensus statement, and the 2009 American Association for the Study of Liver Disease practice guidelines. We sought to determine whether these guidelines identified patients who developed hepatocellular carcinoma (HCC) or who died of non-HCC liver-related deaths for antiviral therapy.

METHODS

The criteria described in the new treatment guidelines were matched to the database of 369 hepatitis B surface antigen-positive patients, in whom 30 developed HCC and 37 died of non-HCC liver-related deaths during a mean follow up of 84 months.

RESULTS

Using criteria for antiviral therapy as stated by the four current guidelines, 19-30% of patients who died of non-HCC liver-related complications, and 23-53% of patients who developed HCC, would have been excluded for antiviral therapy. If baseline serum albumin levels of ≤ 3.5 g/dL or platelet counts of ≤ 130,000 mm(3) were included into the treatment criteria, then 85-94% of patients who developed liver-related complications would have been recommended for antiviral therapy. Also, the addition of precore A1896 mutants and basal core promoter T1762/A1764 mutants would have identified 98.5-100% of these patients.

CONCLUSION

The updated treatment guidelines for hepatitis B still excluded patients who developed serious liver-related complications. The inclusion of baseline serum albumin and platelet counts to current criteria would have identified a majority of these patients for antiviral therapy. These tests should be included into hepatitis B treatment strategies.

Influence of serum HBV DNA load on recurrence of hepatocellular carcinoma after treatment with percutaneous radiofrequency ablation

BACKGROUND

High serum load of hepatitis B virus (HBV) deoxyribonucleic acid (DNA) is a strong risk factor of hepatocellular carcinoma (HCC) development, independent of hepatitis B e antigen, serum alanine aminotransferase level, and liver cirrhosis. We evaluated whether serum HBV DNA load is associated with the risk of recurrence of HBV-related HCC treated with radiofrequency ablation (RFA).

METHODS

The study population was 69 consecutive patients with HBV-related HCC treated locally completely with RFA between January 2000 and September 2007. The risk factors for HCC recurrence were analyzed based on laboratory data, including serum HBV DNA load, together with tumor size and number using univariate and multivariate proportional hazard regression analyses.

RESULTS

HCC recurrence was observed in 42 of 69 patients during the median observation period of 1.5 years. Cumulative recurrence rates at 1, 3, and 5 years were 26.5, 57.8, and 74.3%, respectively. In univariate analysis, albumin (<3.5 g/dl), platelet count (<150 × 10(3)/mm(3)), prothrombin activity (PT) (<70%), Child-Pugh class B, serum HBV DNA load (>4.0 log10 copies/ml), and tumor number (>3) were associated with the recurrence at p ≤ 0.15. Multivariate Cox regression analysis with stepwise variable selection showed that the tumor number (risk ratio, 4.63; 95% CI, 1.50-14.25, P = 0.0076), low PT (3.39, 1.52-5.78, P = 0.0029), and high HBV DNA load (2.67, 1.16-6.14, P = 0.021) were independent risk factors for HCC recurrence.

CONCLUSION

Serum HBV DNA load is associated with the risk of recurrence of HBV-related HCC after RFA.

Hepatitis B e antigen seroconversion: a critical event in chronic hepatitis B virus infection

BACKGROUND

Replication of hepatitis B virus (HBV) is the primary driver of disease progression and clinical outcomes in patients with chronic hepatitis B (CHB), but other factors, such as hepatitis B e antigen (HBeAg) status, also influence disease course. The importance of HBeAg seroconversion is underscored by current CHB treatment guidelines that recommend limiting the duration of antiviral therapy in HBeAg-positive patients who achieve seroconversion.

AIMS

A 2-day meeting of leading hepatologists with extensive experience managing patients with CHB in the Asia-Pacific region was held with the overall goals of reviewing and evaluating (1) available data on the relationship between HBeAg seroconversion and clinical outcomes for patients with HBeAg-positive CHB, and (2) the ways in which seroconversion should influence patient management.

CONCLUSIONS

It was agreed that HBeAg seroconversion is an important serologic end point for patients with CHB and that achieving this goal should be an important consideration in treatment selection. Patients with HBeAg-positive CHB should consider pegylated interferon if they are aged < 40 years (especially women), have lower HBV DNA levels, can afford this treatment, and have a lifestyle that would support adherence to injection therapy. Alternatively, nucleos(t)ide analogs are recommended in patients with alanine aminotransferase levels ≥ 2 × the upper limit of normal, HBV DNA levels < 9 log(10) IU/ml, and compensated CHB. Entecavir, telbivudine, and tenofovir may be used as first-line therapy; they can be administered as a finite therapeutic course in HBeAg-positive patients who seroconvert. Telbivudine and tenofovir should be considered in women of child-bearing potential.

Efficacy of entecavir in chronic hepatitis B patients with mildly elevated alanine aminotransferase and biopsy-proven histological damage

Current guidelines for management of chronic hepatitis B recommend treatment for patients presenting with elevated hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) >2 x upper limit of normal (ULN) or histological evidence of liver disease. Retrospective analyses have demonstrated that significant hepatic necroinflammation and fibrosis were present in a substantial proportion of patients with ALT 1 to 2 x ULN. To assess therapeutic efficacy in this clinical setting, we retrospectively examined treatment endpoints among the subset of nucleoside-naïve chronic hepatitis B (CHB) patients treated in phase 3 clinical trials of entecavir who had both screening and baseline serum ALT 1.3 to 2 x ULN. A total of 1347 patients were randomized to treatment with entecavir or lamivudine. Three hundred thirty-six patients, constituting 25% of the total study population, had screening and baseline ALT 1.3 to 2 x ULN. Clinically significant necroinflammation (Knodell necroinflammation score > or =7) was observed in 60% and 72% of hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients, respectively, whereas marked fibrosis (Ishak fibrosis score > or =4) was observed in 8% and 15% of HBeAg-positive and HBeAg-negative patients, respectively. Among entecavir-treated HBeAg-negative patients, the proportions of patients achieving histological improvement, HBV DNA <300 copies/mL, and ALT normalization were similar between patients with mildly elevated ALT and those with ALT >2 x ULN. However, entecavir-treated HBeAg-positive patients with mildly elevated ALT had lower response rates for histological improvement, HBV DNA less than 300 copies/mL, ALT normalization, and HBeAg seroconversion than those with ALT greater than 2 x ULN.

CONCLUSION

This retrospective analysis demonstrated that HBeAg-negative CHB patients treated with entecavir responded similarly irrespective of baseline ALT level. However, HBeAg-positive patients with mildly elevated ALT responded less well to treatment with entecavir than did those with ALT greater than 2 x ULN.

Withdrawal of lamivudine in HBeAg-positive chronic hepatitis B patients after achieving effective maintained virological suppression. J Clin Virol. 2009;45:114-118. [PMID: 19451024 DOI: 10.1016/j.jcv.2009.04.006]

BACKGROUND

A recommendation was made by the ACT-HBV Asia-Pacific Steering Committee regarding the withdrawal of lamivudine in chronic hepatitis B patients after achieving effective maintained virological suppression. The outcome of patients following this therapeutic guideline has not been clearly investigated.

OBJECTIVE

In this study, we examined the outcome of patients adherent to the lamivudine withdrawal guideline.

STUDY DESIGN

Seventy-one chronic hepatitis B patients achieving seroconversion of hepatitis B e antigen (HBeAg) as well as effective maintained virological suppression during lamivudine therapy were included. Lamivudine was withdrawn provided that undetectable HBV-DNA had been documented on two separate occasions at least 6 months apart. The patients were followed for a median period of 15 months (range, 6-72 months). The effect of pre-therapeutic clinical and virological factors on time to relapse was analyzed.

RESULTS

Of the 71 patients, 19 (27%) relapsed, of whom 5 showed reappearance of HBeAg and 14 had HBeAg-negative hepatitis. Cox proportional hazard model showed pre-therapeutic HBV-DNA level was the only predictor for time-to-relapse (hazard ratio=1.023, 95% confidence interval=1.004-1.043, P=0.020). Categorical analysis showed that 15/34 (44.1%) and 4/37 (10.8%) patients with pretreatment HBV-DNA levels >10(8) and <or=10(8)copies/mL, respectively, relapsed during follow-ups. The accumulative relapse rates were significantly different between the two groups of patients (Kaplan-Meier method, P=0.003).

CONCLUSIONS

In patients with pretreatment HBV-DNA levels <or=10(8)copies/mL, lamivudine could be withdrawn after achieving effective maintained virological suppression. Relapse of HBeAg-negative hepatitis remained a major problem.

Management of chronic hepatitis B in children

Hepatitis B virus (HBV) infection is a worldwide problem and can cause acute liver failure, acute hepatitis, chronic hepatitis, liver cirrhosis, and liver cancer. In areas of high prevalence such as in Asia, Africa, southern Europe, and Latin America, the hepatitis B surface antigen positive rate ranges from 2% to 20%.In endemic areas, HBV infection occurs mainly during infancy and early childhood. Mother-to-infant transmission accounts for approximately half of the chronic HBV infections. In contrast to infection in adults, HBV infection during early childhood results in a much higher rate of persistent infection and long-term serious complications such as liver cirrhosis and HCC.Three phases of chronic hepatitis B have been identified: the immune-tolerant phase, the immune-active phase, and the inactive hepatitis B phase. These phases of infection are characterized by variations in viral replication, hepatic inflammation, spontaneous clearance, and response to antiviral therapy.The optimal goal of antiviral therapy for chronic HBV infection is to eradicate HBV and to prevent its related liver complications. However, due to the limited effect of available therapies in viral eradication, the goal of treatment is to reduce viral replication, to minimize liver injury, and to reduce infectivity. In this review the current recommendations for monitoring and treating chronic HBV infection in children are reviewed.

Chronic hepatitis B: early viral suppression and long-term outcomes of therapy with oral nucleos(t)ides

Chronic hepatitis B is a serious health problem worldwide with a substantial minority of patients experiencing premature death due to end-stage liver disease and/or hepatocellular carcinoma. Antiviral therapy may help prevent complications of chronic hepatitis B, and seven agents are currently approved in many countries. Of these agents, five are nucleos(t)ide analogs that all have a risk of antiviral drug resistance with long-term use. Efforts have been made in the recent years to prevent or to reduce the risk of viral resistance in patients treated with oral nucleos(t)ides as the majority of these patients will require therapy for 3-5 years or longer. One approach is to identify patients who would most likely develop antiviral resistance on long-term therapy using predictors obtainable early in the course of treatment, when intervention with new or additional therapy can be instituted. The most important predictors of treatment outcomes are serum HBV DNA levels at baseline and during the first 6 months of therapy. The purpose of this synopsis is to review the recent literature regarding the importance of serum HBV DNA levels in association with treatment outcomes in chronic hepatitis B, particularly the association of complete viral suppression early in the course of oral therapy with long-term treatment outcomes, particularly the incidence of antiviral drug resistance.

A treatment algorithm for the management of chronic hepatitis B virus infection in the United States: 2008 update

Chronic HBV infection is an important public health problem worldwide and in the United States. A treatment algorithm for the management of this disease, published previously by a panel of U.S. hepatologists, has been revised on the basis of new developments in the understanding of the disorder, the availability of more sensitive molecular diagnostic tests, and the licensure of new therapies. In addition, a better understanding of the advantages and disadvantages of new treatments has led to the development of strategies for reducing the rate of resistance associated with oral agents and optimizing treatment outcomes. This updated algorithm was based primarily on available evidence by using a systematic review of the literature. Where data were lacking, the panel relied on clinical experience and consensus expert opinion. The primary aim of antiviral therapy is durable suppression of serum HBV DNA to low or undetectable levels. Assays can now detect serum HBV DNA at levels as low as 10 IU/mL and should be used to establish a baseline level, monitor response to antiviral therapy, and survey for the development of drug resistance. Interferon alfa-2b, lamivudine, adefovir, entecavir, peginterferon alfa-2a, telbivudine, and tenofovir are approved as initial therapy for chronic hepatitis B and have certain advantages and disadvantages. Although all of these agents can be used in selected patients, the preferred first-line treatment choices are entecavir, peginterferon alfa-2a, and tenofovir. Issues for consideration for therapy include efficacy, safety, rate of resistance, method of administration, and cost.

Treatment recommendations for chronic hepatitis B: an evaluation of current guidelines based on a natural history study in the United States

Current guidelines for treatment of chronic hepatitis B include hepatitis B e antigen (HBeAg) status, levels of hepatitis B virus (HBV) DNA, and serum alanine aminotransferase (ALT) values in the setting of either chronic hepatitis or cirrhosis. Based on findings from a prospective study of hepatitis B surface antigen (HBsAg)-positive patients, we determined whether these guidelines included patients who developed hepatocellular carcinoma (HCC) and who died of non-HCC liver-related complications. The criteria for treatment from four published guidelines were matched to a cohort of 369 HBsAg-positive patients enrolled in the study. During a mean follow-up of 84 months, 30 patients developed HCC and 37 died of non-HCC liver-related deaths. Using criteria for antiviral therapy as stated by the four guidelines, only 20%-60% of the patients who developed HCC, and 27%-70% of patients who died of non-HCC liver-related deaths would have been identified for antiviral therapy according to current treatment recommendations. If baseline serum albumin levels of 3.5 mg/dL or less or platelet counts of 130,000 mm(3) or less were added to criteria from the four treatment guidelines, then 89%-100% of patients who died of non-HCC liver-related complications, and 96%-100% of patients who developed HCC would have been identified for antiviral therapy. In addition, if basal core promoter T1762/A1764 mutants and precore A1896 mutants also were included, then 100% of patients who developed HCC would have been identified for treatment.

CONCLUSION

This retrospective analysis showed that the current treatment guidelines for chronic hepatitis B excluded patients who developed serious liver-related complications.

Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2008 update

Large amounts of new data on the natural history and treatment of chronic hepatitis B virus (HBV) infection have become available since 2005. These include long-term follow-up studies in large community-based cohorts or asymptomatic subjects with chronic HBV infection, further studies on the role of HBV genotype/naturally occurring HBV mutations, treatment of drug resistance and new therapies. In addition, Pegylated interferon alpha2a, entecavir and telbivudine have been approved globally. To update HBV management guidelines, relevant new data were reviewed and assessed by experts from the region, and the significance of the reported findings were discussed and debated. The earlier "Asian-Pacific consensus statement on the management of chronic hepatitis B" was revised accordingly. The key terms used in the statement were also defined. The new guidelines include general management, special indications for liver biopsy in patients with persistently normal alanine aminotransferase, time to start or stop drug therapy, choice of drug to initiate therapy, when and how to monitor the patients during and after stopping drug therapy. Recommendations on the therapy of patients in special circumstances, including women in childbearing age, patients with antiviral drug resistance, concurrent viral infection, hepatic decompensation, patients receiving immune-suppressive medications or chemotherapy and patients in the setting of liver transplantation, are also included.

Natural history and clinical management of chronic hepatitis B virus infection in children

Hepatitis B virus (HBV) infection may cause acute, fulminant, or chronic hepatitis, leading to liver cirrhosis or hepatocellular carcinoma. Despite the availability of effective vaccine, HBV infection during infancy or early childhood is common in areas of high endemicity. In these regions, mother-to-infant transmission accounts for approximately 50% of chronic infections. Although the natural history of HBV infection in adults is well characterized, little information is available in the literature regarding the natural history of HBV infection in children. Similar to infection in adults, chronic HBV infection in children can be divided into distinct phases: immune tolerant, immune clearance, and inactive carrier state. However, acute exacerbation, with reactivation of HBV replication and re-elevation of alanine aminotransferase levels after hepatitis B e antigen seroconversion, is relatively rare in children, in comparison to adults. Although several potent antiviral agents are now available for the treatment of chronic hepatitis B, experience with these agents in the pediatric setting is limited. To date, conventional interferon alpha and lamivudine are the only two antiviral agents approved to treat chronic hepatitis B in children. The rapid emergence of resistant HBV associated with long-term lamivudine therapy, as well as poor tolerability associated with conventional interferon alpha, are factors that should be considered before initiating antiviral therapy. This article reviews current knowledge regarding the natural history and treatment of chronic hepatitis B in children. Factors that affect the natural history of HBV infection in children are also reviewed.

Current approaches for treating chronic hepatitis B: when to start, what to start with, and when to stop

The natural course of hepatitis B virus (HBV) infection is variable, and chronic hepatitis B (CHB) disease exhibits itself through a spectrum of clinical manifestations. These factors contribute to the challenges faced when managing patients who live with HBV infection. Furthermore, conventional treatment options (e.g., interferon alfa-2a, lamivudine, and adefovir) are moderately effective and can be associated with problems, such as poor tolerability (interferon alfa-2a) and the development of drug resistance (lamivudine). Over the last 5 years, several antiviral agents including entecavir, peginterferon alfa-2a, and telbivudine which are more efficacious and have improved tolerability over previous drugs have become available. The availability of novel antiviral agents and advances in understanding resistance patterns of antiviral agents has resulted in refinement of CHB treatment recommendations and guidelines. More recently, evidence from clinical trials suggests the central importance of virologic suppression as an indicator of treatment outcome and the predictive value of on-treatment HBV DNA levels in response to antiviral therapy. This review highlights the goals of therapy and clinical experience with therapies that are newly licensed or in the late stages of clinical development. Current approaches for treating CHB and new strategies for optimizing response to therapy are also discussed.

Economics of chronic hepatitis B and hepatitis C

Although not all patients develop progressive liver disease, chronic hepatitis B and chronic hepatitis C infections cause substantial morbidity and mortality worldwide. To address this need, many new antiviral treatments have become available over the past 10 years. While safety, efficacy, and therapeutic indications have been well established for these agents, the economics of antiviral treatment have become increasingly a focus of discussion for physicians, policymakers, and health payers. In this paper, we will elucidate some economic principles using examples from the treatment of hepatitis B and C. In particular, we will examine the considerations in estimating drug costs, methods for performing economic analyses and lastly summarize published cost-effectiveness analyses for antiviral treatments of chronic hepatitis B and chronic hepatitis C. This review should help clinicians understand economic issues regarding new drugs and answer questions about whether the clinical benefit provided by a medication justifies its expense.