Effectiveness and tolerance of interferon-alpha 2b in the treatment of chronic hepatitis C in haemodialysis patients

Interferon monotherapy of chronic hepatitis C in dialysis patients: meta-analysis of clinical trials

The efficacy of monotherapy with interferon (IFN) (conventional or pegylated IFN) in dialysis patients with chronic hepatitis C remains unclear, although a number of clinical trials have been published addressing this issue. The aim of the study was to evaluate the efficacy and safety of monotherapy by conventional or pegylated IFN in dialysis patients with chronic hepatitis C by performing a systematic review of the literature with a meta-analysis of clinical trials. The primary outcome was sustained virological response (SVR; as a measure of efficacy), and the secondary outcome was drop-out rate (as a measure of tolerability). We used the random-effects model of Der Simonian and Laird, with heterogeneity and sensitivity analyses. We identified 28 clinical trials (645 unique patients), of which six (21.4%) had a controlled design. In the group of trials based on conventional IFN, the summary estimate for SVR and drop-out rate was 39% [95% confidence interval (CI) 32-46] and 19% (95% CI 13-26) respectively. The summary estimate for SVR rate in patients with the hepatitis C virus genotype 1 was 33% (95% CI 19-47). In the subset of trials using pegylated IFN, the summary estimate for SVR and drop-out rate was 31% (95% CI 7-55) and 27% (95% CI 1-52) respectively. The most frequent side-effects requiring interruption of treatment were flu-like symptoms, and gastrointestinal and haematological changes. A relationship between age and drop-out rate was found, even if no statistical significance was reached (P = 0.064). The studies were heterogeneous with regard to SVR and drop-out rate. No publication bias was observed. One-third of dialysis patients with chronic hepatitis C were successfully treated with conventional or pegylated IFN monotherapy. Preliminary evidence does not support additional benefit due to monotherapy with pegylated IFN on the viral response in the chronic kidney disease (CKD) population. Tolerance to IFN monotherapy was unsatisfactory, particularly to pegylated IFN. The optimal antiviral treatment of chronic hepatitis C in dialysis populations is currently under active investigation.

Meta-analysis: interferon for the treatment of chronic hepatitis C in dialysis patients

BACKGROUND

The efficacy of interferon monotherapy in dialysis patients with chronic hepatitis C remains unclear, although a number of small clinical trials have been published addressing this issue.

METHODS AND AIMS

We evaluated the efficacy and safety of initial interferon monotherapy in dialysis patients with chronic hepatitis C by performing a systematic review of the literature with a meta-analysis of clinical trials. The primary outcome was sustained virological response (as a measure of efficacy); the secondary outcome was drop-out rate (as a measure of tolerability). We used the random effects model of Der Simonian and Laird, with heterogeneity and sensitivity analyses.

RESULTS

We have identified 14 clinical trials (269 unique patients); two were controlled studies. The mean overall estimate for sustained virological response (SVR) and drop-out rate was 37%[95% confidence interval (CI) 28-48] and 17% (95% CI 10-28), respectively. The most frequent side-effects requiring interruption of treatment were flu-like symptoms (17%), neurological (21%) and gastrointestinal (18%). The overall weighted estimate for SVR in patients with hepatitis C virus genotype 1 was 30.6% (95% CI 20.9-48). In the sub-group of clinical trials (n = 5) with standard interferon administration (3 million units [MUI] thrice weekly, subcutaneous route, 24-week treatment), the overall mean estimate of SVR was 39% (95% CI 25-56). The studies were heterogeneous with regard to SVR and drop-out rate.

CONCLUSIONS

Tolerance to initial interferon monotherapy was lower in dialysis than nonuremic patients with chronic hepatitis C. However, more than one-third of haemodialysis patients with chronic hepatitis C have been successfully treated with interferon. Longer duration of interferon monotherapy does not appear to have a beneficial effect on the response rate. Further studies are warranted to define the optimal anti-viral regimen for chronic hepatitis C in dialysis population.

Hepatitis B and C and renal failure

Hepatitis C is the most common cause of liver disease in the dialysis patient. The prevalence of chronic hepatitis C determined by anti-HCV testing in this population ranges from 6% to 38%. Using second generation EIA assays, the prevalence of anti-HCV among patients participating in the 1997 National Surveillance of Dialysis Associated Diseases in the United States was 9.3%. Polymerase chain reaction testing for HCV RNA has shown that the prevalence of HCV infection can be as high as 20% to 30% of dialysis patients. The causes and source of infection in patients with chronic renal failure on hemodialysis are multiple. Before the introduction of routine screening of blood donors for anti-HCV, blood transfusions were an important risk factor for acquisition of hepatitis C. Other potential sources of infection include exposure to contaminated equipment and nosocomial routes such as patient-to-patient exposure. The risk of infection appears to correlate with the duration of hemodialysis and the number of transfusions. Interestingly, dialysate and buffers have been shown to be virus free even when used in hepatitis C infected patients. The natural history of chronic hepatitis C infection in patients with renal failure is not well characterized. Although persistent elevations in ALT levels occur in 12% to 50% of dialysis patients, the frequency of persistently normal ALT levels in HCV-infected dialysis patients appears to be higher than in HCV-infected patients without renal failure. Overt liver disease and liver failure rarely occur. The degree of inflammation in liver biopsies of renal failure patients is usually mild. Thus, progressive liver disease may be less common in patients with advanced renal disease but further studies are required to assess the true impact of hepatitis C infection in this high risk population. The impact of hepatitis C infection on morbidity and mortality of patients with end-stage renal disease remains poorly defined. Initial studies have failed to show a significant increase in mortality among HCV-infected hemodialysis or renal transplant patients within the first 5 years following transplantation. In contrast, recent studies with extended follow-up of renal transplant recipients suggest that hepatitis C infection may affect patient and graft survival during the second decade. Further studies are required to identify the mechanisms of infection of patients with end-stage renal disease and to define better treatment strategies for these patients before and after kidney transplantation.

Efficacy of interferon for chronic hepatitis C virus-related hepatitis in kidney transplant candidates on hemodialysis: results after transplantation

OBJECTIVES

Interferon-alpha (IFN) may have undesirable effects on a functioning graft. The aim of this study was to evaluate IFN treatment in kidney transplant candidates during the hemodialysis period as well as the results after transplantation.

METHODS

A total of 29 noncirrhotic hemodialysis patients with chronic hepatitis C virus (HCV) infection (based on long-term rise in ALT, HCV serology, HCV RNA by polymerase chain reaction methods, and histological evidence) were included. Tolerability to IFN treatment, pre- and posttransplantation therapeutic results, and long-term outcome were recorded. IFN regimen consisted of 3 million units (MU) times per week after hemodialysis sessions for 6 months, followed by 1.5 MU after each hemodialysis session for an additional 6 months. All patients gave informed consent for participation.

RESULTS

IFN therapy was fairly well tolerated. Adverse effects due to IFN toxicity, renal disease, or causes related to the immunological properties of IFN were observed in 24% of patients. At the end of treatment, ALT had normalized in 23/28 patients (82.1%), and HCV RNA had cleared in 23/28 patients (82.1%). During follow-up, HCV RNA was persistently negative in 18 patients (64%, including transplant recipients). A total of 14 patients (nine HCV RNA-negative) received a kidney transplant. Mean follow-up after the procedure was 41 +/- 28 months. In all, 12 patients had a functioning graft, one had acute vascular rejection, and one died of carcinoma. All transplanted patients maintained normal ALT levels, and eight remained HCV RNA-negative.

CONCLUSIONS

Treatment results in our study population were better than those observed in the general population. The long-term response achieved, which was maintained after transplantation, supports the use of IFN for HCV hepatitis in kidney transplant candidates under hemodialysis.

Hepatitis C and renal failure

Chronic hepatitis C virus (HCV) infection is common among patients with chronic renal failure. This chronic viral infection can result in significant morbidity and mortality. Liver failure from chronic hepatitis C is one of the leading causes of death among long-term survivors of renal transplantation. HCV infection also can be a cause of glomerulonephritis and nephrotic syndrome. Recognition of these conditions is important to optimize the management of these patients.

Pharmacokinetics of natural human IFN-alpha in hemodialysis patients

A pharmacokinetic study of natural human interferon-alpha (IFN-alpha) was conducted in hemodialysis patients. Natural human IFN-alpha was intramuscularly (i.m.) administered to 8 hemodialysis patients at a single dose of 5 million IU and to 7 patients undergoing hemodialysis at the same dose once daily for 5 successive days. The serum antiviral activity was determined by a cytopathic effect bioassay. In the single dose study, the serum antiviral activity reached a maximum (Cmax) of 56.4 +/- 33.3 IU/ml at 8.3 +/- 2.7 h after dosing, and the area under the serum concentration-time curve (AUC0-24h) was 957.2 +/- 601.8 IU h/ml. The Cmax and AUC0-24h values at day 5 following the repeated dosing were both 2.6-fold higher than those of day 1, and the serum antiviral activity reached a steady state within 3 days after initiation of repeated administration. The serum antiviral activity in hemodialysis patients showed a tendency to increase compared with that in the subjects with normal renal function, but the magnitude of the differences was not great. In one nonhemodialysis patient with poor renal function (creatinine clearance < 30 ml/min), no increases in serum antiviral activity owing to repeated dosing were observed. The main adverse events seen were fever (4 of 13, 30.8%), leukopenia (3 of 13, 23.1%), and fatigue (2 of 13, 15.4%). These results suggest that dosage modifications of natural human IFN-alpha are unnecessary for patients with low renal function, even those undergoing hemodialysis.

Hepatitis in patients with end-stage renal disease

Hepatitis B and hepatitis C are two common pathogens causing chronic hepatitis in patients with end-stage renal disease (ESRD). With the acceptance of hepatitis B s antigen (HBsAg) screening, infected patients have been identified and isolated over the past 20 years. Consequently, hepatitis B is now being seen less frequently in dialysis units. Even though hepatitis B has become less of a problem, non-A, non-B hepatitis has been recognized as a significant problem since 1979. With the availability of serological testing for hepatitis C virus (HCV), more specific information is now available in regard to HCV infection in dialysis patients. The prevalence of anti-HCV in haemodialysis (HD) patients is quite variable, ranging from 5 to over 50%. Anti-HCV positivity is associated with previous blood transfusions, mode of therapy and duration of haemodialysis. In Spain and Italy, the annual seroconversion rates of HCV antibodies in dialysis patients are 2-9%; this rate was much higher in Taiwan (15%). Whether patients with HCV infection should be identified and isolated during HD treatment is an issue of controversy. Transplantation is associated with increases in hepatitis B virus (HBV) replicative markers. The survival disadvantage in HBsAg-positive recipients usually did not become apparent until 8 years after transplantation. Hepatitis C virus-infected renal transplant recipients are presumably in a similar situation to patients with hepatitis B, although confirmatory data are currently lacking. Coinfection of HBV and HCV may lead to aggressive liver disease and cirrhosis. A hepatitis B vaccine is recommended for all susceptible dialysis patients. Dialysis patients have lower response rates to hepatitis B vaccines than do other people. Currently, no vaccine is available for hepatitis C. To date, there are no effective treatments available for hepatitis B and hepatitis C. Combination therapy with interferon/lamivudine for hepatitis B and interferon/ribavirin for hepatitis C may offer a promise of effective control of viral replication in the future.