Hepatitis B Virus Infection and Anti-HBc ( Total ) Positivity in CKD Patients before Dialysis

Background: CKD patients are associated with HBV infection both as a cause and complication of treatment. CKD patients before starting dialysis therapy are considered as a high risk group because of impaired immune response compared with healthy individuals and also other risk factors related with treatment and management. Only HBsAg marker does not always follow the presence or absence of HBV infection. Anti-HBc (total) alone positivity indicates previous exposure to HBV infection, window period and even after reactivation of resolved HBV infection. In some cases only anti-HBc positivity is interpreted as possible chronic low dose HBV infection (chronic carriage). Predialytic CKD patients were tested with three serological markers [HBsAg, anti-HBc (total) and anti-HBs] for screening HBV infection. Proper diagnosis before dialysis and knowing the infection status would help both the patient and doctor to choose proper treatment approach. Objective: This cross-sectional study was done in the CKD patients before starting dialysis therapy to find out the HBV infection and to evaluate the infection by minimal serological markers as for screening. Materials and Methods: A total of 211 patients with chronic kidney disease stage five (CKD-V) before starting dialysis therapy were included as subjects of this cross-sectional study. Among the CKD patients HBsAg was tested to see the prevalence. Other serological markers, i.e., anti-HBc (total) and anti-HBs were tested in combination with HBsAg in 89 randomly selected patients among the subjects. The patients were also tested for anti-HCV to assess co-infection. After collecting all the data of different test results analyses were done by SPSS version 15.0. Results: Among total study population 10 (4.7%) patients were found HBsAg positive. No patient was found positive for both HBsAg and anti-HCV. Among the 89 CKD patients only 2 (2.2%) patients were HBsAg positive, and only one patient (0.9%) was found positive for both anti-HBc and anti-HCV. Of them, a total of 22 (24.7%) patients were anti-HBs positive, and 35 (39.3%) patients were anti-HBc (total) positive. Of the three markers anti-HBc (total) alone positivity were in 20 (22.5%) patients. Conclusion: Data indicate a large proportion of HBV infected patients were underdiagnosed by usual screening method by HBsAg in our country. The finding of anti-HBc (total) alone cannot be clearly interpreted in terms of patient prognosis or infectivity. Patients are simply regarded as potentially infectious. Due to this uncertainty, different countries employ different procedures when faced anti-HBc alone findings. In some countries including ours the test is not performed. Since a substantial number of CKD patients with HBV infection have this antiHBc (total) positivity, standard screening procedures and precautions should be taken in blood donation, hemodialysis and for other invasive procedures to prevent transmission of infection.

Chronic kidney disease (CKD) is a worldwide problem with increasing incidence and prevalence of 10.3-13.7% in different countries. [1][2][3] It is frequently associated with liver diseases. Hepatitis B virus (HBV) infection as one of the most common causes of liver disease can cause CKD and CKD patients can acquire HBV infection during the course of management. Management of the CKD p a tients a ssociated with t hese infections is coupled with a d verse effects a n d higher rate of morbidity a n d mortality. 4,5 These infections a r e transmitted primarily t hrough t he parenteral route. Sexual and vertical routes also have some role in transmission. Some studies have shown that nosocomial transmission is not rare. CKD patients are at increased risk o f a cquiring HBV infection as a r esult of nosocomial spread or exposure to infected blood and blood products. 6 While the risk of transmission of these two viruses has been considerably reduced in developed countries owing to increased screening procedures [7][8][9] , the problem is not properly addressed in developing countries like Bangladesh. Because of common modes of transmission, HBV infection may co-exist with HCV infection and is r e latively high in transfusion recipients. [10][11][12] The prevalence of HBV infection (HBsAg seropositive) among patients on maintenance hemodialysis in the developed world is currently low (0-10%) but remains higher (2-20%) in developing countries. 4 CKD patients with HBV infection may be more likely to develop chronic infection once exposed to HBV. 6 Because of the immune dysfunction, acute HBV infection is often mild or asymptomatic in CKD patients, and in contrast to normal adults, the majority of them become chronic carriers due to impaired viral clearance. 13,14 The antibody response to HBV vaccine in CKD patients is reduced and declines logarithmically with time. 15 CKD p a tients ultimately undergo end stage renal therapy like dialysis for their treatment and survival. Risk factors for the infections are more in dialysis period than in predialytic stages. For this reason the CKD patients should be properly diagnosed knowing the infection status before dialysis which would help both the patient and doctor to choose the proper way of treatment to prevent nosocomial transmission and to use properly screened blood product by sterile technique.
There are different serological and molecular markers for the diagnosis of HBV infection and to assess the immunity against the infection. Most commonly in endemic a r eas, HBV chronic carriage stage with HBsAg too low to be detected is recognized by the presence of anti-HBc (total) as the only serological marker referred to as 'anti-HBc alone' or 'isolated anti-HBc'. 16 So, for rapid diagnosis and screening purpose minimal serological markers of HBV infection like HBsAg, anti-HBc (total) and anti-HBs may be done to comply with time and cost and to know the infection immune status to prevent transmission. We should have knowledge about the existence of the HBV infection in CKD patients before dialysis as immune response is reduced in CKD p a tients compared to healthy individuals and the patient may get infection during course of management. A very few studies are available regarding prevalence of HBV in CKD patients before dialysis. 17 In this study it has b e en attempted to determine the prevalence of HBsAg in the predialytic CKD patients and minimal serological markers, i.e., HBsAg, anti-HBc (total) and anti-HBs were tested to determine HBV infection status and immune stage of the infected or vaccinated patients. This will help in reducing the transmission of infection, and thereby taking further necessary action.

Materials and Methods
This cross-sectional study was carried out during the period from July 2011 to June 2012. A total of 211 patients with CKD stage five (CKD-V) [Estimated glomerular filtration rate (eGFR) <15 mL/min/1.73m 2 for >3 months] before starting dialysis therapy were included in this study. Patients with CKD admitted in the Department of Nephrology in National Institute of Kidney Diseases and Urology hospital were tested and included as subjects of this study. CKD stage five was assessed according to the relevant history and based on age, sex and serum creatinine value. According to Kidney Disease Outcome Quality Initiative (KDOQI) guideline patients with e stimated GFR <15 mL/min/1.73m 2 for > 3 months was considered as CKD-V. 18  Introduction condition of the infected or vaccinated patients. All predialytic CKD patients were screened for HBsAg. Among a l l study subjects 8 9 p r edialytic C KD patients were taken randomly and tested in addition for anti-HBs and anti-HBc (total). Antibody to HCV was tested to see co-infection. Only 89 subjects were managed for testing the additional serological markers due to fund constraint. HBV infection and HBV vaccination stages were assessed and analyzed. After collecting all the data of different test results analyses were done by SPSS version 15.0.

Results
Total 211 CKD patients before starting dialysis therapy were included in the study. Of them 121 were male and 90 were female with mean age 43.93 ± 15.68 years. All patients were tested for HBsAg. Among them 10 (4.7%) patients were found positive for HBsAg and 201 (95.3%) patients were HBsAg negative.
Among a l l predialytic C KD p a tients 8 9 C KD patients were included randomly t o t e st the serological markers of HBV infection. HBsAg, anti-HBs and anti-HBc (total) were done to know the infection status whether the patient had no infection or got cured of HBV infection or was in window period. In addition, the patients might have old infection or chronic infection or acute infection or the patient might get HBV vaccination.
Among the 89 CKD patients only 2 (2.2%) were HBsAg positive, 22 (24.7%) patients were anti-HBs positive and 35 (39.3%) patients were anti-HBc (total) positive. All the serological markers were analyzed combined to detect CKD patients with or without HBV infection in pre-dialysis stage into six categories: no HBV infection (HBsAg -ve, anti-HBc -ve, a n ti-HBs -ve), a cute HBV infection (incubation period)/recent vaccination (HBsAg +ve, anti-HBc -ve, anti-HBs -ve), chronic/acute infection (HBsAg +ve, anti-HBc +ve, anti-HBs -ve), old cured infection (HBsAg -ve, anti-HBc +ve, anti-HBs +ve), HBV infected patient with window period/old infection without protective antibody/ chronic carriage anti-HBc alone (HBsAg -ve, anti-HBc +ve, a n ti-HBs -ve) and patients had vaccination (HBsAg -ve, anti-HBc -ve, anti-HBs +ve). CKD patients with an isolated positive test for anti-HBc IgG or anti-HBc (total) are called anti-HBc alone. Among the 89 CKD patients only one patient (0.9%) was found positive for both anti-HBc (total) and anti-HCV. No patient was found positive for both HBsAg and anti-HCV. The following table shows analysis of the results of three serological tests (HBsAg, anti-HBc [total] and anti-HBs) of HBV infection and vaccination. The patients who developed protective antibody anti-HBs against hepatitis B virus b e came immune and noncontagious. The two groups; old cured infection (HBsAg -ve, anti-HBc +ve, anti-HBs +ve) and previously vaccinated patients (HBsAg -ve, anti-HBc -ve, anti-HBs +ve) developed anti-HBs and immunity. So, among total CKD patients about 24% developed protective antibody against HBV.

Discussion
Hepatitis is one of the most common causes of mortality in CKD patients ranking third in number after cardiovascular disease and infection. Prevention and treatment of hepatitis gain more importance in the treatment of CKD patient. 19 22 In Bangladesh, there is paucity of information on the prevalence of HBV and HCV infections among general population and majority of the previous studies were conducted in selected group of people with higher risk factors such a s b l ood donors, d r ug a d dicts, commercial sex workers ( C SWs) or hospitalized patients. [23][24][25][26][27] However, a report showed 5.5% HBsAg positivity among the general population living in Savar, a semi-urban area on the outskirts o f Dhaka. 28 According to another study 29 29 In the present study 10 (4.7%) patients were found HBsAg positive among 211 predialytic CKD patients, which is comparable with the previous studies in Dhaka 28,29 and lies within the range of 2 -7%, reported by previous studies from selective and general population. [23][24][25][26][27][28][29] Out of the total population only 89 predialytic CKD patients were tested for anti-HBc and anti-HBs due to fund constraint. Among the 89 CKD patients only 2 (2.2%) patients were HBsAg positive, 22 (24.7%) patients were anti-HBs positive, and 35 (39.3%) patients were anti-HBc (total) positive. No patient was found positive for both HBsAg and anti-HBc. So, a total of 37 (41%) CKD patients have been found seropositive (HBsAg p o sitive and anti-HBc positive) for HBV infection which is higher than the total seropositivity [582 (29%)] percentage found in general population in another study. 29 Only anti-HBc positive percentage (39.3%) was found higher in CKD patients than in general population (22.6%). 29 As the dialysis patients are higher risk group to get the infections, there may be discrepancy in pre-dialysis and dialysis p e riod regarding t hese infections. In Bangladesh, around 12% of patients on maintenance hemodialysis were serologically positive for hepatitis B virus infection. 30 In India, HBV prevalence was 8.8% and 14.2% in predialysis a n d hemodialysis group respectively. 31,32 In Turkey, prevalence of HBV was 10.5% and 4.9--6.5% in predialysis and hemodialysis patients r e spectively. 17,33 In another study 34 in Bangladesh, researchers included 25 predialytic patients and 63 maintenance hemodialysis patients and HBsAg positivity was more (16%) in predialysis compared to 1.6% in hemodialysis period. Our data of HBsAg positivity differ from above study in predialytic CKD patients. 34 Improvements in the national vaccination programs, reduction of transfusion numbers due to erythropoietin administration and implementation of compulsory blood donor screening have reduced the number of HBV infection. But still due to diminished immune response and lack of thorough blood screening HBV infection remains a m ajor concern in HD centers. 35 HBV prevalence by HBsAg seromarker has b e en evaluated in many studies and also in present study. But presence or absence of only HBsAg marker does not always follow t he presence or absence of HBV infection. Here 89 predialytic CKD patients were tested and analyzed by other serologic markers for HBV, anti-HBc and anti-HBs in addition to HBsAg. Only three serological markers were included to analyze the HBV infection for screening purpose to make it cost-effective and to prevent transmission of infection. C ured condition having protective antibody (anti-HBs) against HBV r e flect immune stage and infected patients without anti-HBs were non-immune. Some individuals with 'anti-HBc alone' carry HBV in their serum, their proportion varies greatly between 0.2% in blood donors and 47% in intravenous drug abusers. 38 In HBV endemic areas, anti-HBc alone or isolated anti-HBc positive patient may have HBV chronic carriages stage with HBsAg too low to be detected and recognized by the presence of anti-HBc as the only serological marker. 16,35 So the finding of anti-HBc alone cannot be clearly interpreted in terms of patient prognosis or infectivity. Patients are simply regarded as potentially infectious. Due to this uncertainty different countries employ different procedures when faced anti-HBc a l one findings. In case of blood donation, many countries including United States test blood for anti-HBc (total) and discard the blood from anti-HBc alone positive donors. 35 This test is not performed in some countries including ours. Since individuals with anti-HBc alone are considered potentially infectious and a substantial number of CKD patients with HBV infection have this anti-HBc a l one positivity, standard screening procedures and precautions should be taken in blood donation, hemodialysis a n d for other invasive procedures to prevent transmission of infection.