Prevalence of hepatitis C virus infection and risk factor analysis in Changsha, central China, about population undergoing routine check-up, 2013–2015

Background Currently, Hepatitis C virus (HCV) infection remains a major public health problem. The aim of current study wanted to determine the prevalence of HCV virus infections, and to explore the risk factors for HCV infection in the general adult population undergoing routine check-ups in Changsha City. Methods We collected 59688 blood samples from the adult population undergoing routine check-ups in 2013– 2015 and obtained relevant information using a standardized questionnaire. We then conducted association and logistic regression analyses. We used the enzyme immunoassay method to test for anti-HCV antibodies in the serum samples. Results The positivity rate of anti-HCV was about 0.57% (340/59688) in the general population. Participants from rural areas showed significantly higher HCV seroprevalence rates than did those from the urban area (0.83% vs 0.19%, p < 0.001). HCV seropositivity increased progressively with age, peaking at 55–64 years (1.23%), and decreasing in participants aged 65 and older. The positivity rate of anti-HCV for males was slightly higher than that of females (0.67% vs 0.48%, p = 0.002). The results of multiple logistic regression showed that history of blood transfusion, surgery, living in rural areas, and transmission in families were the main risk factors for HCV infection. Conclusions: The prevalence of HCV infection is low in the general population in Changsha. This information vital for healthcare settings and health education entities in public, especially in rural areas.


Background
Hepatitis C virus (HCV) is an RNA virus that is a hepacivirus in the flaviviridae family.It is primarily transmitted through sexual contact and blood products [1].Some patients with chronic HCV infections may develop cirrhosis or even hepatocellular carcinoma [1,2], which is becoming a severe public health problem.According to WHO statistics, in 2014 approximately 130 to 150 million people were infected chronic hepatitis C (CHC), and more than 350 thousand people died from HCV infection related liver diseases, cirrhosis and liver cancer.According to previous reports, male gender, blood transfusion history, medication history, and familial HCV infection are common risk factors for HCV infection [3,5].Because of insufficient information regarding the prevalence of HCV infection in Changsha, we investigated the general population to evaluate the prevalence characteristics and risk factors of HCV infection.

Study area and population
Changsha is one of the largest cities in central China; it is located in Hunan province and is home to 800 thousand citizens.The distribution of residents in urban and rural areas is equal, enhancing the reliability of this investigation.Cluster random sampling was adopted to screen out 59688 patients presenting for physical examinations at our hospital from 2013 to 2015, when testing for hepatitis C antibody was carried out.These subjects had an average age of 48.31 ± 14.62, range 15-92 years.A total of 27543 were male and 32145 were female.

Data collection
We designed unified questionnaire to acquire general information including age, gender, and residential area.All subjects were asked about their exposure history including history of blood donation, surgery, blood transfusion, ear piercing, dental treatment, invasive procedure, unsafe sexual contact, tattooing and intravenous drug abusers.(The specific content of the questionnaire is shown in supplementary material 1).Trained physicians administered questionnaire and recorded relevant information.

Sampling method
The sample size was calculated as follows: Detection of anti-HCV antibodies Fasting venous blood (5 mL) for serum isolation was collected under sterile conditions, and then cryopreserved at -20 ° C. Enzyme-linked immunosorbent assay (ELISAs) (Xinchuang Core Anti-HCV ELISA kit, Xiamen, China) were used to measure serum anti-HCV, according to manufacturer's instructions.When the OD value of sample was near the "gray area," the sample was repeated to determine the final testing results.

Statistical analysis
The experimental results were analyzed using SPSS 11.7 software.Continuous variables were expressed as mean standard difference, and counting data were expressed as percentages.The χ2 test was used to measure the overall distribution difference of classification variables and the global distribution difference of continuous variables in line with normal distribution was measured by the T test.When p < 0.05, the results were considered statistically significant.The risk factors for the disease were analyzed using univariate and multivariate logistic regression.Odds ratio (OR) and 95% confidence interval were calculated.

Demographic characteristics
A total of 59688 serum samples were collected from the participants who were available for HCV testing.A total of 24560 (41.15%) were from the urban area and 35128 (58.85%) were from the rural area.There were 27543 (46.14%) males and 32145 (53.86%) females.The ages ranged from 15 to 92 years, with a mean of 48.31 ± 14.62 years.There were no significant differences between the genders (χ2 = 9.403, p = 0.002).We grouped all individuals into seven age groups: 15-24, 25-34, 35-44, 45-54, 55-64 and ≥ 65 years.The specific demographic characteristics are shown in table 1.

Area, age and gender distribution of anti-HCV positive rate
A total of 340 individuals were anti-HCV positive by ELISA.The anti-HCV positive rate of the entire population was 0.57%.The rate in the rural population was 0.83%, significantly higher than that of the urban area (p < 0.001).The anti-HCV positivity rate for male subjects was 0.67%, compared with 0.48% in females.The difference in prevalence between men and women was not statistically significant (p = 0.002).The rate of anti-HCV seropositivity increased with age (p < 0.001), peaking in the 55-64 group (1.24, 183/14793), and then decreased.The lowest anti-HCV prevalence was in the 15-24 group (0%, 0/6763) (Table 2).

Risk factors for HCV infection
In univariate analyses, gender, age, living in rural area, blood transfusion, history of surgical procedures, dental treatment, invasive procedures and ear piercing and transmission in families were associated with anti-HCV seropositivity (p < 0.05 or p < 0.01) (Table 2).However, the multivariate analysis showed that blood transfusion, living in the rural area, surgical procedures and transmission in families remained independently associated with HCV infection (p < 0.05 or p < 0.01) (Table 3).

Discussion
We found that the anti-HCV-positive rate of the general population in Changsha was 0.57% (340/59688), significantly lower than the previously reported rate of 2.26% in Hebei province in 1992 [6,7].This possibly due to improvements in medication and quality of life in recent years, especially the safety of blood transfusion.The rate was very close to the screening result of 157,168 people in Jiangsu province, where the total positive rate of anti-HCV was 0.79% [8]and the screening result of 438,575 people in the city of Mianyang, west China, where the total positive rate of anti-HCV was 0.80% [9].Min et al. reported that blood transfusion, surgery, or with a previous diagnosis of hypertension were significant risk factors for HCV infection in 2015 in the city of Mianyang [9].A study by Yuliang Zhao in 2013 in Hebei Province found that history of blood transfusion and transmission in families, lived in rural area and aged 40-59, were significantly associated with HCV seropositivity [10].Our results showed a significant association between the gender, age, a history of dental treatment, invasive procedures, ear piercing surgery, blood transfusion, transmission in families and living in a rural area and HCV.
In particular, the last four factors were the independent variables associated with HCV infection.Many of the identified risk factors in our study were similar to those of previously reports.
In the present study, the anti-HCV positive rate in rural areas was significantly higher than that in urban areas corresponding with previous study results in China [11,12].We considered that this phenomenon may be caused by different economies, lifestyles and education in the two regions.
Another important reason might be commercial blood selling in rural areas.Some studies had showed that the paid blood donors had a comparatively higher HCV infection rate [13,14].Before 1998, there were number of people selling blood in the countryside in China.Individuals sell blood to illegal blood collection agencies who had no legal business license for payment [15].Therefore, some of the illegal collection agencies generally used unsafe blood collection methods, and reused of non-sterilized needles, that could easily spread HCV infection.
We found that participants who had a history of blood transfusion were more likely to have HCV infection.Many studies in China showed that having a history of blood transfusion is a very important risk factor [16,17] for HCV infection, primarily because of illegal blood donation in some rural areas in the late 1980s.
We found that participants who had a history of surgery had a higher infection rate of HCV.More than 20 years ago, the hospitals in some underdeveloped areas often spread HCV infection due to inadequately sterilized medical equipment, in the context of no HCV test before surgery.Furthermore, transmission in family members was important risk factor for HCV infection.The same results were obtained in other studies [10,18].It might be that the corresponding family members were infected from a common source instead of the index patients; however, the high infection rate of intra-familial clustering was based on the assessment of risk factors for person-to-person viral transmission.Moreover, in past decades, the general population lacked healthcare and HCV transmission knowledge due to their lower levels of education.
There were several limitations in this study.First, HCV virological assessments including HCV RNA levels and HCV genotypes were not performed.Second, based on the subjects' memories, recall bias was a limitation.Therefore, future surveillance studies of this virus are warranted in a broader population.Moreover, it may be difficult to self-report some behaviors, such as injecting drug use.

Conclusions
This large-scale study revealed that the infection rate of HCV among the population in Changsha was slightly lower in the general population than the national average.Despite its limitations, our study provided reference data for improving the level of infection control in healthcare settings as well as public health education regarding HCV infection, especially in rural areas.

TABLE 1 .
Demographic characteristics of study population

TABLE 2 .
Single factor analysis of HCV infection and related risk factors

TABLE 3
Factors associated with seropositivity of Hepatitis C identified in multiple logistic regression