Acute Hepatitis C in Patients Receiving Hemodialysis

Abstract

Hepatitis C virus (HCV) infection is frequent in patients with end-stage renal disease treated by chronic dialysis, with a prevalence varying from 10–65% according to the geographical data. The prevalence is significantly associated with the duration of dialysis and the number of transfused blood products and has dramatically declined with efficient blood screening. We studied patients with acute HCV infection in a dialysis unit. The diagnosis was based on both anti-HCV detection and HCV-RNA detection. Other virological tools including HCV genotype determination was also used to tailor treatment to the individual patient and determine its efficacy for a one-year follow-up period. Seventeen patients (7 male and 10 female, mean age: 63.7 ± 11.6 SD) with acute hepatitis C were enrolled to our study. All of them were followed up for a period of one year after the diagnosis was established. Phylogenetic analysis distinguished two separate HCV subtypes 1b, which were both responsible for this acute infection (see ). These types did not differ in their behavior on the clinical situation of our patients, as confirmed by the fact that in both groups of patients, there was only one patient who presented with acute illness. Six patients of our study group, three months after the acute infection, received pegylated interferon (Peg-IFNa2a) 135 μg for a six-month period. Four of them responded very well to therapy and at the first determination HCV RNA was below the cutoff point. One of our patients with very high HCV levels (HCV RNA > 50,000,000 IU/mL), despite receiving the same therapy, did not respond well and developed cirrhosis. In conclusion, it is clear from our experience that better information is needed about the current incidence, prevalence, and risk factors for HCV infection in dialysis patients. Algorithms for the diagnosis and management of hepatitis C should be developed by academic societies. Routine screening for hepatitis C also would allow for better definition of the natural history of hepatitis C in patients with end stage renal disease.

Figure 1. NS 5B gene phylogenetic tree analysis of the acute hepatitis C epidemic.

INTRODUCTION

Hepatitis C virus (HCV) infection is frequent in patients with end-stage renal disease treated by chronic dialysis, with a prevalence varying from 10–65% according to the geographical data. The prevalence is significantly associated with the duration of dialysis and the number of transfused blood products[1],[2] and has dramatically declined with efficient blood screening.[3] Despite the high efficacy of blood screening and erythropoietin therapy, HCV contamination persists with a yearly incidence of 1.4%, with evidence of nosocomial transmission.[4],[5] Hemodialysis patients are at particularly high risk for blood-borne infections because of prolonged vascular access and the potential for exposure to infected patients and contaminated equipment. The incidence of seroconversion from negative to positive fell to 0.56% and then to 0% when universal precautions were reinforced, although the average number of transfusions and proportion of patients with dialyzer reuse or with monitors disinfected after each session did not change.[6]

Apart from the considerable variability in the prevalence of anti-HCV infection in dialysis units worldwide, there is also great variability in HCV testing practices in dialysis units. Virological diagnosis and monitoring of HCV infection are based on two categories of laboratory tests, namely serologic assays detecting specific antibody to HCV (anti-HCV, indirect tests) and assays that can detect, quantify, or characterize the components of HCV viral particles, such as HCV RNA and core antigen (direct tests). Direct and indirect virological tests play a key role in the diagnosis of infection, therapeutic decision-making, and assessment of the virological response to therapy.[7]

There are very few studies regarding acute HCV infection, and the problems with these published papers are explained by the nature of acute HCV itself. Acute HCV is common, and patients typically present at different stages of the disease with greatly variable signs, symptoms, and biochemical abnormalities. Acute HCV may not be diagnosed correctly, and accurate diagnosis may be delayed. There are still no specific tests to identify acute infection with HCV, and the outcome is not readily predictable from clinical and serological tests.[8]

We studied patients with acute HCV infection in a dialysis unit. The diagnosis was based on both anti-HCV detection and HCV-RNA detection. Other virological tools including HCV genotype determination were also used to tailor treatment to the individual patient and determine its efficacy for a one-year follow-up period.

PATIENTS AND METHODS

Seventeen patients (7 male and 10 female, mean age: 63.7 ± 11.6 SD) with acute hepatitis C were enrolled to our study. All of them were followed-up for a period of one year since the diagnosis was established. Prospectively, blood samples were collected from each patient before hemodialysis session three times a week for three months and then once per week for three months. After six months, blood collections continued with a rate 1–2 samples per month until one year after diagnosis of acute infection completed.

Anti-HCV was typically identified by using immunoassay. It detects mixtures of antibodies directed against various HCV epitopes located in the core. The specificity was greater than 99%, but sensitivity was more difficult to determine given the lack of gold standard. Clinical experience indicates that anti-HCV is positive in more than 99% of immunocompetent patients with detectable HCV-RNA.

The amplicon was detected by real time PCR technique. The principle is to detect amplicon synthesis and deduce the amount of viral genomes in the starting clinical sample during rather than at the end of the PCR reaction. This method is more sensitive than classical target amplification techniques and is not prone to carry-over contamination. Its dynamic range of quantification is consistently wider, making it particularly useful for quantifying the full range of viral loads observed in untreated and treated patients (see Table 1). The lower detection cutoff of current assay was below 615 IU/mL.

Table 1 Qualitative HCV RNA detection

PCR: Amplicor HCV 2.0 (Roche)

• cutoff: 50 IU/mL

• equal sensitivity for all HCV genotypes

• specificity: > 99%

• semi-automation on the Cobas Amplicor

Real-Time PCR

• Improved sensitivity.

• Wide, dynamic range of quantitation.

• No carry-over or cross-contaminations.

• Full automation expected.

For molecular determination of the HCV genotyping, a gold standard was used: direct sequencing of the NS5B (329bp), followed by sequence alignment with reference sequences and phylogenetic analysis. The HCV genotype is an intrinsic characteristic of the transmitted HCV strain and does not change during the course of infection. HCV genotypes form six clads or types (numbered 1–6) (see Figure 2) and are themselves subdivided into a large number of subclads or subtypes identified by lower-case letters (1a, 1b, 1c, etc). Phylogenetic analysis was performed, which can distinguish HCV types, subtypes, and isolates on the basis of average sequence divergence rates of approximately 30%, 20%, and 10%. Typing errors are uncommon, but subtyping errors may occur in 10–25% of all cases.

Figure 2. HCV genotypes.

RESULTS

Phylogenetic analysis distinguished two separate HCV subtypes 1b, which were both responsible for this acute infection (see Figure 1). These types did not differ in their behavior on the clinical situation of our patients. This element was confirmed by the fact that in both groups of patients, there was one patient presented with acute illness.

Levels of HCV RNA were compared with levels of ALT from the beginning until the day 156 from the start of the acute infection (see Figure 3). We noticed in two patients (patients 15 and 16) a significant decrease of HCV level (>2 log) with a parallel increase of ALT level. As we may notice in Figure 3, in all of the other patients of our study, kinetic of HCV and ALT levels were parallel.

Figure 3. Comparison HCV RNA (top line) and ALT levels (bottom line) in each patient.

Six patients of our study group, three months after the acute infection, received pegylated interferon (Peg-IFNa2a) 135 μg for a six-month period. Four of them responded very well to therapy and at the first determination. HCV RNA was below the cutoff point. One of our patients with very high HCV levels (HCV RNA > 50,000,000 IU/mL); although he received the same therapy, he did not respond well and developed cirrhosis.

DISCUSSION

HCV is a small double-shelled virus consisting of a lipid envelope (E) with virally consisting encoded glycoproteins (E1, E2) and nonstructural (NS: P7,NS2,NS3,NS4A, NS4B,NS5A and NS5B) components. The nonstructural proteins encode several proteases, a virus-specific helicase and an RNA-dependent RNA polymerase responsible for replication of the genome. HCV isolates, as it has been noticed, are classified into 6 distinct clads based on sequence homology (fig. 2). The virus circulates in serum asquasispecies in the envelope proteins E1 and E2.[9]

Exposure to infectious material is followed by the appearance of HCV RNA in serum within 1 to 2 weeks. Viral levels increase rapidly and serum alanine aminotransferase (ALT). Values generally become abnormal as HCV levels peak 4–8 weeks after the exposure. Antibody to HCV arises later, and the initial antibody response is targeted mostly against HCV core, NS3 and NS4 proteins. Recovery is marked by loss of HCV RNA and resolution of disease activity, whereas chronicity is marked by persistence of viremia (see Figure 4).[10]

Figure 4. Time course of HCV RNA in patients with (A) evolution to chronic injection, and (B) acute, spontaneously resolving hepatitis C.

In the present study, the spread of hepatitis C began from a hospitalized patient under hemodialysis after blood transfusion. The outbreak of the infection that followed connected with health care-related procedures. Assessing risk is based on the epidemiologic characteristics of HCV, including modes of transmission, which persons are at increased risk or have a high prevalence of infection, and the amount of disease or infection attributable to the risk. In 1998, the Centers for Disease Control and Prevention (CDC) convened a meeting of expert consultants to review the available data and develop recommendations for the prevention and control of HCV infection. However, outbreaks of HCV infection have been recognized in chronic hemodialysis patients (CDC, unpublished data).[11] These outbreaks were associated with the use of contaminated equipment and unsafe injection practices. The second behavior seems applicable to the outbreak of our dialysis unit.[12]

In our study, we used three virological markers of HCV infection, namely, HCV genotype, HCV RNA, and anti-HCV antibodies.

Genetic heterogenicity is one of the most relevant biological characteristics of the HCV. Comparative analysis of the genomic sequences of the virus isolated in different parts of the world has led to the identification of up to six different HCV genotypes and much more subtypes (see Figure 2). The HCV subtype responsible for the infection in our study was 1b. It is one of the genotypes (1a, 1b, 2a, and 2b) that are widely distributed around the world.[13] The influence of the genotype of the virus on the severity of the disease is controversial. Several studies suggested that the most severe forms of liver disease, such as cirrhosis and hepatocellular carcinoma, are significantly associated with infection with virus of genotype 1b. Although it can not be used as supportive data, we remind the reader that one of our patients developed cirrhosis. However, the existence of any relationship between the severity of the disease and the virus genotype has not been confirmed by other authors.[14],[15] There are many possible explanations for the discrepancies among different studies, such as different characteristics of the patient population analyzed, genetic and environmental factors, gender, and age.

The presence of HCV RNA in peripheral blood is a reliable marker of active HCV perlication, which takes place principally in the liver. HCV RNA is detectable in serum 1–2 weeks after infection. It generally increases to reach a peak before disappearing when the infection resolves spontaneously, a fact that we observed in two of our patients. The HCV RNA levels are not affected by the severity of liver disease. In our study, the patients with the clinical illness did not have significant different levels of HCV RNA compared with the asymptomatic ones.

Acute hepatitis C is often mild and associated with few, if any, symptoms. Fulminant or severe cases are rare. Two of our patients presented with symptoms. Although the rate of chronic outcome is high, it can vary from as low as 40–50% to as high as 90–100%, depending on patients' age and sex (younger and female patients having lower rate of chronicity), the source of infection and size of inoculum (the highest risk for chronicity appears to be associated with post-transfusion hepatitis), and clinical features during acute phase (asymptomatic cases being more prone to progress to chronic hepatitis compared with cases with symptomatic disease).

Apart from the clinical situation, the most important finding is that acute hepatitis C has a high propensity to become chronic, which provides the rationale for treating patients with acute disease attempting to prevent chronicity. Because studies of treatment of acute hepatitis have been limited in size and included a heterogeneous population of patients, there have been few analyses of factors that predict a response. Six of our patients treated for a six-month period, starting three months after diagnosis, were confirmed.

In most studies of therapy of acute hepatitis C, treatment was delayed for 1–4 months after onset, a period of time needed to recognize the disease and make a positive diagnosis. Indeed, treating patients before the onset of symptoms and marked ALT elevations may be counterproductive because the antiviral therapy may only be effective in the setting of an active host immune response to the infection. Thus, available data suggest that delaying therapy by 2–4 months after onset may be a reasonable strategy to achieve these goals, but these conclusions are based on limited and preliminary experience.[16],[17]

Pretreatment HCV-RNA levels were reported in few studies, and a statistical significant association between lower initial levels of virus and sustained virological response was found.[18],[19] In our population, we have not noticed this kind of information. HCV genotypes 2 and 3 have been reported to have the highest rates of response. Factors of age, sex, race, obesity, and liver histology have not been analyzed. However, if the response rates are truly as high as 83–100% in acute hepatitis C (67% responders in our study from preliminary data), these factors are unlikely to show a significant correlation with response or lack of response.

A six-month course of peginterferon, as in our patients, seems the most rational approach. There is convincing evidence that interferon monotherapy reduces the rate of progression of acute to chronic hepatitis C. However, the optimal regimen of therapy has not been defined, particularly in terms of risk versus benefit. There have not been any studies of interferon-ribavirin combination therapy.

Studies on the natural history of acute hepatitis C have indicated the need for an accurate and prolonged virological follow-up evaluation to predict long-term outcomes. Our study is underway in order to ensure the resolution of HCV infection in our patients. There is a critical need for regular, prolonged follow-up of treated patients well beyond the 24 weeks after treatment, the period usually needed in evaluating outcome in chronic hepatitis C. Therapeutic studies of acute hepatitis C, such as ours, provide an excellent venue for ancillary studies on the viral and immunopathogenesis of acute infection.

In conclusion, it is clear from our experience that better information is needed about the current incidence, prevalence, and risk factors for HCV infection in dialysis patients. The CDC recommendations for screening and infection control practices to prevent and monitor HCV transmission should be widely adopted, including mounting a practical and efficient educational effort to train dialysis personnel in hemodialysis precautions. Algorithms for the diagnosis and management of hepatitis C should be developed by academic societies. Routine screening for hepatitis C also would allow for better definition of the natural history of hepatitis C in patients with end stage renal disease.