Saudi Journal of Kidney Diseases and Transplantation

: 2007  |  Volume : 18  |  Issue : 1  |  Page : 107--113

The Impact of Polymerase Chain Reaction Assays for the Detection of Hepatitis C Virus Infection in a Hemodialysis Unit

Magdi M Hussein1, Jaap M Mooij1, Mohamed S Hegazy1, Mohammed S Bamaga2,  
1 Department of Nephrology and Dialysis, The Al Hada Armed Forces Hospital, Taif, Saudi Arabia
2 Department of Laboratory Medicine and Molecular Pathology, The Al Hada Armed Forces Hospital, Taif, Saudi Arabia

Correspondence Address:
Magdi M Hussein
Department of Nephrology and Dialysis, Al Hada Armed Forces Hospital, P.O.Box 1347, TAIF
Saudi Arabia


Hepatitis C virus (HCV) infection is most often diagnosed by detection of antibodies against the virus (HCV Ab). However, it has been reported that some HCV Ab negative patients test positive for HCV-RNA. Over a study period of 30 months, all patients on hemodialysis at the Al Hada Armed Forces Hospital in Taif, Saudi Arabia were tested monthly for HCV Ab and twice per year for HCV-RNA. HCV Ab was tested by a third generation microparticle enzyme immunoassay (MEIA), and HCV-RNA by a qualitative hepatitis-RNA assay, second version (COBAS Amplicor ® PCR), which was recently introduced in the Molecular Pathology Laboratory of our hospital. Of the 180 patients studied, 34 (18.9%) had positive HCV Ab, and of the 146 HCV Ab negative patients, five patients tested positive for HCV-RNA (3.42 %). Our study further finds that, when applying HCV Ab testing only, some patients with HCV viremia may be undetected. For better HCV infection control, routine HCV­RNA testing of dialysis patients should be considered, particularly in areas where the infection is common and in units applying isolation policies.

How to cite this article:
Hussein MM, Mooij JM, Hegazy MS, Bamaga MS. The Impact of Polymerase Chain Reaction Assays for the Detection of Hepatitis C Virus Infection in a Hemodialysis Unit.Saudi J Kidney Dis Transpl 2007;18:107-113

How to cite this URL:
Hussein MM, Mooij JM, Hegazy MS, Bamaga MS. The Impact of Polymerase Chain Reaction Assays for the Detection of Hepatitis C Virus Infection in a Hemodialysis Unit. Saudi J Kidney Dis Transpl [serial online] 2007 [cited 2021 Jan 20 ];18:107-113
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Full Text


Hepatitis C virus (HCV) infection is associated with a poor prognosis for survival among dialysis patients. [1],[2] Commonly, HCV is diagnosed by detection of antibodies against the virus (HCV Ab). However, it has been reported that 2.5 to 12% of patients with active HCV infection, as manifested by detectable serum levels of hepatitis C-RNA (HCV-RNA), test negative for antibodies against the virus. [3],[4],[5] In some patient groups, such as immunocompromised patients, in which the antibody response is suppressed, this number might be even higher. In one study from Saudi Arabia, 28% of the dialysis patients who were anti-HCV negative by third generation ELISA tested positive for HCV-RNA. [6]

These findings indicate that significant numbers of patients with active HCV infection will remain undetected when only anti-HCV Ab assays are used, with unforeseen consequences. In our hospital, we recently introduced an HCV-RNA assay to test all patients routinely for HCV infection, in addition to standard hepatitis C serology screening. This study was undertaken to detect the prevalence of HCV-RNA in HCV Ab negative patients.

 Patients and Methods

Since mid 2003, blood samples from all patients on hemodialysis (HD) at the Al Hada Armed Forces Hospital in Taif, Saudi Arabia were taken on a monthly basis for detection of anti-HCV Ab, and in addition twice per year for detection of the presence of HCV-RNA. Anti-HCV antibodies were analyzed using a third generation micro­particle enzyme immunoassay (MEIA) (Abbott Axsym ®, Abbott Laboratories, Abbott Park, IL, USA). The sensitivity and specificity of this test, as mentioned by the manufacturer, are 100 % and 99.6 %, respectively. [7] HCV-RNA was analyzed through a qualitative hepatitis-RNA assay (COBAS Amplicor ® PCR), version 2 (Roche Diagnostics, Branchburg, NJ, USA). [8] This assay has a detection limit of approximately 50 copies of HCV-RNA per ml; the number of copies ranges from 60 to 100 per ml for plasma and serum, respectively. [9]

Most of the patients who tested positive with the HCV qualitative assay underwent further quantitative testing with the COBAS Amplicor HCV Monitor TM Test, version 2 (Roche Diagnostics, Branchburg, NJ, USA). [10] The values of this test results are given as IU/ml. All HCV-PCR tests were carried out at the Molecular Pathology Laboratory of our hospital by medical technologists who were trained by Roche to run the reverse-transcriptase PCR assays. The tests are performed in a specially designated area for molecular protocols to prevent cross contaminations.

For the purpose of this study, the duration on dialysis was defined as the time on dialysis both prior to the study and during the study period. The end of the study period was set at December 31, 2005, or earlier if the patient was transplanted, expired, or lost to follow-up (e.g. transferred to another hospital). Patient data, including age (at the end of the study) and duration on dialysis are presented as mean ± standard deviation, are shown in [Table 1]. The correlations between two parameters (duration on dialysis and number of HCV Ab positive patients) were calculated using the two-tailed Pearson bivariate correlation coefficient. The level of significance was set at p A possible explanation for the absence of antibodies in a patient with active viremia might be the known suppressed cellular immunity in the dialysis population, causing a reduced ability to mount a detectable antibody response to the virus. In this context, it is known that hepatitis B vaccinations in dialysis patients do not always result in an antibody response (despite doubling of the vaccine dose). [16],[17],[18] A similar lack of immune response to vaccination has also been associated with the malnutrition-inflammation-cachexia syndrome (MICS), which leads to a poor prognosis in dialysis patients. [19]

Failure to detect HCV Ab in an HCV­RNA positive patient might also occur in the so-called "window" period between infection and anti-HCV seroconversion, which might be prolonged in dialysis patients. [20] In some other cases, it may be due to disappearance of anti-HCV antibody despite persistence of viremia.[11] The prevalence of positive HCV Ab patients in our dialysis center was 18.9%. Five patients in the HCV Ab negative group were positive for HCV-RNA. One of them was known to be HCV Ab negative and HCV-RNA positive before dialysis, while two patients were shown to be HCV-RNA positive at the start of the dialysis period; thus, the infection might have been acquired prior to commence­ment of dialysis treatment. However, one patient, who had already been on dialysis for 50 months, became positive for HCV­RNA during the study period, while for another patient, who had been on dialysis for 10 months and HCV-RNA positive and Ab negative at the start of the study, the HCV serology became "equivocal" after six months during the study period, again suggesting a recent infection.

The prevalence of HCV positive serology in our unit was found to be well below the 47.8% reported for dialysis patients in the Kingdom of Saudi Arabia as a whole in 2002.[21] The reason for this difference might be that in our center, in addition to adherence to universal infection control precautions [11],[13],[14],[15] from an early stage, specific policies were developed for dialysis of HCV Ab positive patients to prevent the spread of infection. They include isolation from other patients and the use of designated dialysis machines in these patients. [22] These isolation policies are not recommended as routine strategies to control nosocomial transmission of HCV in dialysis units and are not included in the CDC guidelines. [15] Nevertheless, they were applied in our unit in view of the high prevalence of HCV infection in the area.

Despite these isolation policies, a potential risk for spread of the infection always remains, if some of the HCV-serology negative patients happen to be active carriers of the virus. This might explain why, during the study period, despite the adherence to universal infection control precautions, and the designation of special machines to HCV Ab positive patients, fresh cases of HCV infection, possibly dialysis-related, were seen in our unit. This observation might also be supported by the finding in our study of a strong positive correlation between the duration on dialysis and HCV Ab positivity. Some investigators recommend routine testing for HCV-RNA in all dialysis patients [5], [23], [24] while others recommend it only for the HCV Ab negative patients. [25] The CDC guidelines recommend performing the test only for patients with abnormal liver function tests and negative HCV-serology. [15]

In areas with a high prevalence and incidence of HCV infection, and in view of the signi­ficant morbidity and mortality associated with HCV infection, testing for HCV-viremia might be a valuable tool, despite the high costs, to improve the diagnosis of HCV infection and, by doing so, to reduce the risk of spreading. [5], [20], [23], [24], [26]


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