Introduction
Chronic hepatitis B (CHB) infection is a common liver disease that affects 257 million people globally (1). The prevalence of hepatitis B surface antigen (HBsAg) ranges from 0.7 to 6.8% worldwide. Turkey is middle endemic region for CHB infection, according to World Health Organization (WHO) data.
With effective vaccination programs, active and passive immunizations of newborns born from infected mothers and increased sanitation, the prevalence of HBsAg has declined over the past years. However, it still remains one of the most important causes of liver cirrhosis and hepatocellular carcinoma (HCC) all over the world, especially in underdeveloped countries. In a systematic review between 1999-2009, HBsAg positivity was found to be 4.6% in our country (2). Currently, according to public health data, about 2 million people in Turkey (2% of the population) are considered to be positive for HBsAg (3).
In Turkey, Hepatitis B virus (HBV) vaccine has been included in the national vaccination schedule in 1998. And catch-up immunization has been performed in primary schools. Thereby the vast majority of the generation born after 1990 has been vaccinated.
In the study, our aim is to compare the seroprevalence of HBsAg and anti-HBS by birth-date in Sungurlu State Hospital, Çorum.
Materials and Methods
The results of patients who applied to our hospital between January 2018 and October 2019 for any reason and who tested for HBsAg and anti-HBs were scanned retrospectively on the electronic system. As our study was retrospective, ethical approval and patients consent were not obtained. A total of 1486 patients were evaluated. The patients were divided into three groups according to their birth dates; 1. born before 1990 (918 cases), 2. born between 1991-1997 (216 cases), 3. born in 1998 and after (352 cases). The rate of HBsAg and Anti-HBs seropositivity were compared by birth-date.
Statistical Analysis
SPSS 21 program was used to analyze the data. Chi-square and Mann-Whitney U were used to compare categorical and continuous variables respectively. Post-hoc analysis with bonferroni correction was used for statistically significant results in the presence of more than two groups. P-value ≤0.05 was considered significant.
Results
Of 1486 cases, 737 were women and 749 were men. The median age was 38 (0-95 years). HBsAg positivity was 1.9% (29) and anti-HBs positivity was 54.2% (805). While 27 of the HBsAg positive patients were born before 1990, 2 patients were born in between 1990-1998. HBsAg positivity was found almost 3 times higher in the male population (Table 1). Of 29 patients with HBsAg positivity, 21 were male and 8 were female, the difference between the genders was statistically significant (p=0.02). Eight patients were inactive HBsAg carriers and 7 were under antiviral treatment with the diagnosis of CHB. Fourteen patients (48%) were without follow-up. Anti-HBs positivity was 41% in patients born before 1990, and 71% in those born in 1998 and after (p>0.001). Anti-HBs positivity was slightly higher in men (Table 1), but not statistically significant (p=0.10). Anti-HCV positivity was 0.4% (6/1447) and anti-HIV positivity was 0.1% (2/1332).
Discussion
With effective vaccination programs, although the incidence of HBsAg has been decreasing all over the world, CHB is still the most important cause of liver cirrhosis and HCC-related deaths. It is estimated 887.000 deaths per year (1). In Turkey, approximately 2% of the population are considered to be HBsAg positive, and 40-50% of liver transplantations between 2012 and 2016 were caused by complication of HBV infection (3,4). On the other hand, as the disease remains silent without having complication, most patients are unaware of their illness. While, only 10.5% of HBsAg positive individuals are thought to be aware of their disease worldwide, this rate was found 12% in a study in Turkey (1,5). In our study, 14 of 29 HBsAg positive patients (48%) did not have CHB follow-up.
Vaccination is the most effective way to control and prevent the disease. HBV vaccination provides 98-100% protection from HBV infection. In 1992, WHO called for vaccination of infants against HBV worldwide, thereafter, vaccination programs for HBV have been conducted in most countries. In Turkey, HBV vaccine has been included in the national vaccination program since 1998. According to Public Health Agency data, the rate of vaccination for hepatitis B increased from 64% in 1999 to 98% in 2018 in Turkey. While the incidence of acute hepatitis B was 4-6 per 100.000 in 1990, it was reported as 1.9 per 100.000 in 2017 in our country. Under the age of 15, this rate has decreased to less than 1 per 100.000 (3).
HBV vaccine is the first vaccine that prevent from cancer. In a study published in 1997 in Taiwan, it was observed that there was a significant decrease in childhood HCC cases after the HBV vaccination program (6). In another study from Alaska, it was emphasized that there was a significant decrease in acute hepatitis B and HCC cases in childhood after the national vaccination program (7).
The results of our study showed a significant decrease in CHB infection with the national vaccination program. HBsAg positivity was found 1.9% in our study group, and all patients were born before 1998. The results were consistent with the rate of our country (2%). HBsAg positivity was found 2.5% in a study including 61.943 volunteers from 73 provinces (8). In another study from Turkey, HBsAg was found positive in 4.75% of 58.752 cases and 97% of the cases were born before 1998 (9). In a review HBsAg positivity in pregnant women between 1975-2016, it was seen that HBsAg positivity varied between 1.2-19.2%. This rate was decreased to 1.2-5.2% after 2010 (10).
While the anti-HBs positivity was found to be about 70% in the first 3 decades, it decreased below 40% in the subsequent decades. As of the 7th decade, it seems that anti-HBs positivity started to increase again (Table 2). This increase is thought to be associated with increased disease contact. In a study published in 2016, similar to our study, anti-HBs positivity was 85.56% in the 0-12 age group and 56.4% in the 13-20 age group, it decreased to 20% within the 20 years. In those over 50 years old, anti-HBs positivity increased again and rises above 40% (11).
Study Limitations
This study had some limitations including retrospective design, low number of cases and unknown of patients anti-HBc IgG status. Prospective studies are needed to better demonstrate these findings.
Conclusion
HBV infection is a communicable disease that can have fatal complications. Immunization is very important and effective way in its control and prevention. With national vaccination program, it is clear that the incidence of the disease has decreased considerably. Therefore, it is very essential to administer HBV vaccination to all people, especially those at risk.
Ethics
Ethics Committee Approval: As our study was retrospective, ethical approval was not obtained.
Informed Consent: Patient consent was not obtained.
Peer-review: Internally peer-reviewed.
Authorship Contributions
Surgical and Medical Practices: S.Y.K, A.K., Concept: S.Y.K, A.K., Design: S.Y.K, A.K., Data Collection or Processing: S.Y.K, A.K., Analysis or Interpretation: S.Y.K, A.K., Literature Search: S.Y.K, A.K., Writing: S.Y.K, A.K.
Conflict of Interest: Authors declare no conflict of interest.
Financial Disclosure: There was no aid and sponsor for this study.