The prevalence of hepatitis B virus infection markers and socio-demographic risk factors in HIV-infected patients in Southern Brazil

Introduction: Hepatitis B virus (HBV) and human immunodefi ciency virus (HIV) infections are two of the world’s most important infectious diseases. Our objective was to determine the hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc) prevalences among adult HIV-infected patients and identify the associations between socio-demographic variables and these HBV infection markers. Methods: This study was performed from October 2012 to March 2013. Three hundred HIV-seropositive patients were monitored by the Clinical Analysis Laboratory of Professor Polydoro Ernani de São Thiago University Hospital, Santa Catarina, Brazil. The blood tests included HBsAg, anti-HBc immunoglobulin M (IgM) and total anti-HBc. Patients reported their HIV viral loads and CD4+ T-cell counts using a questionnaire designed to collect sociodemographic data. Results: The mean patient age was 44.6 years, the mean CD4 T-cell count was 525/mm3, the mean time since beginning antiretroviral therapy was 7.6 years, and the mean time since HIV diagnosis was 9.6 years. The overall prevalences of HBsAg and total anti-HBc were 2.3% and 29.3%, respectively. Among the individuals analyzed, 0.3% were positive for HBsAg, 27.3% were positive for total anti-HBc, and 2.0% were positive either for HBsAg or total anti-HBc and were classifi ed as chronically HBV-infected. Furthermore, 70.3% of the patients were classifi ed as never having been infected. Male gender, age >40 years and Caucasian ethnicity were associated with an anti-HBc positive test. Conclusions: The results showed an intermediate prevalence of HBsAg among the studied patients. Moreover, the associations between the anti-HBc marker and socio-demographic factors suggest a need for HBV immunization among these HIV-positive individuals, who are likely to have HIV/HBV coinfection.

Hepatitis B virus (HBV) infection and human immunodefi ciency virus (HIV) infection are two of the world's most important infectious diseases.HBV infection constitutes a major public health problem in many countries.More than two billion people have been infected with HBV worldwide, and 350 to 400 million people are chronic carriers 1 .It is estimated that nearly 600,000 people die annually from complications related to hepatitis B 2 .Approximately 70 million people have been infected with HIV; 35 million death shave occurred among individuals with acquired immunedefi ciency syndrome (AIDS), and there are approximately 35 million HIV carriers 3 .Among the people currently living with HIV worldwide, approximately 8%, or 3 million, are chronically infected with HBV 4 .
Coinfection with HBV and HIV is commonly observed because these viruses share common routes of transmission 5,6 .The prevalence of HBV/HIV coinfection refl ects geographical variations 7 , and the predominant routes of HBV transmission often correlate with the degree of endemicity.Most new infections occur among adults and are acquired sexually or through injectable drug use in minimally endemic settings.Conversely, exposure to chronically infected household members and perinatal transmission are the horizontal transmission routes that result in greatest amount of disease transmission in highly endemic countries.Countries with an intermediate endemicity exhibit a mixture of these transmission routes 8 .
HBV coinfection may increase morbidity and mortality in HIV-seropositive patients.In addition, HIV infection increases the risk of chronic HBV infection and promotes a faster progression to cirrhosis and its complications, particularly when HBV replication is high [9][10][11]

METHODS
The seropositivity of HBV infection markers among HIVinfected individuals ranges from 4.2% to 19.4% for hepatitis B surface antigen (HBsAg) 5,[12][13][14][15][16][17][18] and 22.9% to 70.4% for hepatitis B core antibody (anti-HBc) 12,14,16,17,19,20 .Studies have reported positive associations between HIV/HBV coinfection and such factors as sex, age, education level, intravenous drug use and homosexual activity 21,22 .In this study, the aim was to determine the prevalence of HBsAg and anti-HBc among an adult population infected with HIV regardless of antiretroviral therapy use to evaluate the different socio-demographic profi les of HIV/HBV coinfected subjects and to evaluate the presence of HBsAg and anti-HBc-associated factors in HIV-positive patients.
This cross-sectional study was performed at the Clinical Analysis Laboratory of Professor Polydoro Ernani de São Thiago University Hospital in the State of Santa Catarina, Brazil between October 2012 and March 2013.The cohort consisted of 300 patients aged ≥18 years who were infected with HIV-1, were treated with or without antiretroviral therapy and were monitored clinically and by the laboratory.
The patients answered a self-administered questionnaire that consisted of the following modules: socio-demographic characteristics, including sex, age, ethnicity, annual income, and the highest level of education achieved; HIV-related risks; cluster of differentiation for (CD 4 ) T-cell count; HIV viral load; time (in years) since HIV infection diagnosis; and years of antiretroviral therapy.
Antiretroviral therapy, CD 4 T-cell count, HIV viral load, time since diagnosis of HIV infection and length of treatment time were included as variables to investigate whether they are associated with the prevalence of HBV infection markers.
A cut-off of 500 cells/mm 3 for the CD 4 T-cell count was utilized according to the Protocol and Therapeutic Guidelines for the Clinical Management of HIV Infection in Adults 23 , which recommends initiating antiretroviral therapy when CD 4 lymphocyte counts are ≤500 cells/mm 3 .
A blood sample was collected from each patient for the qualitative determination of HBsAg and anti-HBc.Anti-HBc immunoglobulin M (IgM) tests were performed using samples obtained from HBsAg-positive patients.After the serum was separated, HBsAg and anti-HBc were detected using a chemiluminescence microparticle immunoassay (CMIA) commercial kit (ARCHITECT®, Abbott Diagnostics, Sligo, Ireland) according to the manufacturer's instructions.These results were categorized as either positive or negative according to the provided cut-offs.
Using bivariate analysis, we compared the HBsAg-positive and HBsAg-negative individuals to identify the sociodemographic variables that were likely to be associated with the presence of these markers in anti-HBc-positive and anti-HBcnegative patients.The variables included in the analysis were age, gender, ethnicity, education level, monthly income, time since HIV infection diagnosis, years of antiretroviral therapy, HIV transmission route, HIV viral load, and CD 4 T-cell count.
Pearson's chi-square test was used to compare the proportions.Statistical significance was set as p<0.050.To identify the parameters associated with anti-HBc, variables with p<0.200 in the bivariate analysis were evaluated with multiple logistic regression using the stepwise method.Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS®) for Windows version 17.0 (SPSS, Chicago, IL, USA) and MedCalc® version 12.4.0(MedCalc Software bvba, Ostend, Belgium).

Ethical considerations
This study was approved by the Ethics Committee of the Federal University of Santa Catarina (Protocol 94.398).

Informed written consent was obtained from all participants.
A total of 300 patients were enrolled in this study (179 males and 121 females), and the average age of the subjects was 44.6 years (range: 18 to 81).The patients' mean CD4T-cell count at the time of HBV testing was 525/mm 3 (range: 90 to 1,446), and the average total antiretroviral therapy time and time since HIV diagnosis were 7.6 years (range: 0 to 25) and 9.6 years (range:1 to 27), respectively.
The overall prevalences of HBsAg and total anti-HBc were 2.3% (7/300) and 29.3% (88/300), respectively.Among the individuals analyzed, 0.3% (1/300) were positive for HBsAg, 27.3% (82/300) were positive for total anti-HBc, and 2% (6/300) were positive either for HBsAg or total anti-HBc.All of the HBsAg-positive patients who tested positive for total anti-HBc had negative anti-HBc IgM results and were classifi ed as chronically infected.None of the patients had positive anti-HBc IgM test results.The absence of HBsAg and anti-HBc was observed in 70.3% of the examined patients (211/300), who were classifi ed as never having been infected (Table 1).
The statistical analyses indicated that none of the sociodemographic or clinical variables studied were associated with positive HBsAg (Table 2).However, caucasians (p=0.049),men (p<0.001),people with incomes ≥US$1,300 (p=0.032),patients over 40 years old (p=0.001),men who had sex with men and patients who were part of an intravenous drug use (IDU) risk group (p=0.005) were more likely to have an anti-HBc positive test compared with patients with African ancestry, members of non-intravenous drug user riskg roups, females, patients with an income <US$1,300 and those aged ≤40 years old (Table 3).In the stepwise logistic regression analysis, non-Caucasian individuals and women had a signifi cantly lower risk of being anti-HBc positive.Conversely, individuals older than 40 years had an increased risk of being anti-HBc positive (Table 4).
Taking into account the seropositivities of 0.3% for HBsAg and 2% for HBsAg and total anti-HBc, this study revealed an overall seropositivity of 2.3% for HBsAg.The prevalence of HBsAg carriers identifi ed in this study can be considered intermediate 29 .In addition, the prevalence of HBsAg in our study is lower than the continental HBsAg prevalence of 9.1% that was estimated for HIV-seropositive patients by the EuroSIDA Study Group in 1998, which included the United Kingdom, Ireland, Norway, Sweden, Denmark, Germany, Holland, Luxembourg, France and Switzerland 30 and countries in which the HBV infection prevalence in the general population was estimated to be less than 1%.
When we compared our results with those from a 1999 study performed in the same region that also examined HIV seropositivity 31 , we found reductions in the prevalences of HBsAg, anti-HBc and HBV chronic infection from 28.8%, 95.5% and 24.3% to 2.3%, 29.3% and 2%, respectively.
Studies performed in southern Brazil between 2009 and 2010 showed that the vaccination coverage of children and adolescents who were born after the hepatitis B vaccination was introduced was over 92% 32 and that the HBsAg and anti-HBc prevalences were less than 1% and 10%, respectively [32][33][34][35] .Hepatitis B virus vaccination began in 1992 for children younger than fi ve years of age and subsequently expanded to health professionals, students, fi refi ghters, police and the military in 1994 and to adults under 20 years old in 2001 36 .Considering that the marked reduction in the prevalence of HBV infection markers among the general population is primarily a result of immunization against hepatitis B, vaccination may have also contributed to the decreased prevalences of HBsAg and anti-HBc that were observed in HIV-infected individuals between 1999 and 2013.
Studies performed in the United Kingdom and the United States among HIV-infected children and adults 14,37 also found a signifi cant decrease in the prevalence of HBV infection markers (HBsAg and anti-HBc) ten and fi fteen years after hepatitis B vaccinations were introduced.Considering the expanded availability of the hepatitis B vaccine to people in older age groups and the expansion of risk groups, which resulted in the near-universalization of the vaccine 36,38 , it is possible that the prevalence of HIV/HBV coinfection and the prevalence of HBsAg and anti-HBc in the general population may decline signifi cantly over the next decade, resulting in true therapeutic reductions in pathologies caused by HBV infection, such as hepatocellular carcinoma and liver cirrhosis.
Regarding the 2% chronic HBV infection prevalence observed in this study, it is important to note that the worldwide prevalence of chronic HBV infection in HIV-infected patients is approximately 10% 39 .However, studies have shown that HBVdeoxyribonucleic acid (HBV-DNA) can be detected in patients with serological profi les that would traditionally be interpreted as previously infected or never infected 16,40 and in patients who are also seropositive for anti-HBc 41 .The prevalence of occult hepatitis B infection in HIV-positive patients with isolated anti-HBc ranges from 0% to 89% 42 .Thus, additional studies are required to better assess the prevalence of chronic hepatitis B infection among HIV-seropositive patients.
Importantly, we found that anti-HBc was most prevalent among males, people over 40 years old and people of Caucasian ethnicity.Moreover, non-Caucasian people and women had a signifi cantly lower risk of being anti-HBc positive.The association between male gender and a high anti-HBc prevalence was also observed in previous studies 16,43,44 and can be explained by males' higher rate of promiscuity and more frequent exposure to risk factors for transmission 5 .The association between anti-HBc and age over 40 years that we observed in our study can be explained by the increased chance of HBV infection that results from a longer lifespan and life time exposure to unprotected sex, unprotected sexual relationships and mother-to-child transmission.Importantly, older patients are also less likely to have been vaccinated for HBV or to have contracted HBV before they contracted HIV because vaccinations for individuals over thirty years of age did not begin until 2013 36 .The signifi cant association between Caucasian ethnicity and anti-HBc prevalence may be attributable to the socio-demographic characteristics of the study population.Our study's population differs from the populations of studies performed in the United Kingdom and Germany; in those countries, there were stronger associations between HBV infection markers and patients who were non-Caucasian patients or originated from endemic regions 14,16 .One limitation of the present study is that the cohort is only representative of the population of HIV-infected patients of Florianópolis, State of Santa Catarina.However, the results of this study provide valuable data for targeting HBV immunization campaigns among HIV-infected patients, who are more likely to exhibit HIV/HBV coinfection, and may help to improve preventive actions.
The results of this study indicated an intermediate prevalence of HBsAg among HIV-infected patients in southern Brazil.In addition, the prevalence of the anti-HBc marker was signifi cantly associated with the sex, age and ethnicity of the HIV-infected patients, suggesting the need for HBV immunization campaigns that focus on those HIV-positive individuals who are most susceptible to coinfection.Despite the observed decline in the prevalence of HBsAg and anti-HBc, prevention campaigns are important to encourage the adult population to vaccinate and to reaffi rm that vaccination is the most effective way to avoid both HBV infection and diseases that result from infection, such as hepatocellular carcinoma.

TABLE 1 -Prevalence of the HBV infection markers HBsAg and anti-HBc among 300 HIV-infected patients in Southern Brazil from October 2012 to March 2013.
HBV: hepatitis B virus; HBsAg: hepatitis B surface antigen; anti-HBc: hepatitis B core antibody; HIV: human immunodefi ciency virus.

TABLE 2 -Socio-demographic and clinical variables potentially associated with isolated HBsAg prevalence in 300 HIV-infected patients in Southern Brazil from October 2012 to March 2013.
HBsAg: hepatitis B surface antigen; HIV: human immunodefi ciency virus; MSM: men who have sex with men; IDU: intravenous drug user; CD4: cluster of differentiation 4.www.scielo.br/rsbmtI www.rsbmt.org.br

TABLE 3 -Socio-demographic and clinical variables potentially associated with anti-HBc prevalence among 300 HIV-infected patients in Southern Brazil from October 2012 to March 2013.
Anti-HBc: hepatitis B core antibody; HIV: human immunodefi ciency virus; MSM: men who have sex with men; IDU: intravenous drug user; CD4: cluster of differentiation 4.*Statistically signifi cant at p<0.050.

TABLE 4 -Multiple logistic regression analysis of socio- demographic variables associated with anti-HBc prevalence among 300 HIV-infected patients in Southern Brazil from October 2012 to March 2013.
Anti-HBc: hepatitis B core antibody; HIV: human immunodefi ciency virus; OR: odds ratio; 95% CI: confi dence interval.*Statisticallysignifi cant at p<0.050.