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Prevalence and risk factors for Helicobacter pylori infection in southwest China: a study of health examination participants based on 13C-urea breath test Featured

It has been well established that peptic ulcer disease, chronic gastritis, and gastric malignancies are strongly related to Helicobacter pylori (H. pylori) infection. H. pylori has been identified by the WHO as a dangerous carcinogen.

Background/aim: Helicobacter pylori (H. pylori) has a high prevalence in developing countries. We aimed to investigate the current prevalence of H. pylori, as well as its potential serum risk factors, in a population from southwest China.

Materials and methods: This cross-sectional study included 10,912 subjects who received medical examinations at the First Affiliated Hospital of Chongqing Medical University in 2014. Data regarding physical examinations and biochemical measurements were collected, and H. pylori infection was diagnosed with a 13C-urea breath test. Logistic regression was conducted to identify the risk factors for H. pylori infection.

Results: The infection rate of H. pylori was 34.4% (3750/10,912). Older age, lower albumin levels, and higher total cholesterol, LDLcholesterol, and fasting blood sugar were significantly associated with increased incidence of H. pylori infection. Moreover, logistic regression analysis showed that older age, low albumin, and hyperglycemia were independent risk factors for H. pylori infection after adjusting for other covariables.

Conclusion: The results from our study showed that H. pylori was prevalent in southwest China. Older age, low albumin levels, and hyperglycemia were significant risk factors associated with H. pylori infection.

( LIU J., et al. Turk J Med Sci (2017) 47: 1456-1462)

1. Introduction

It has been well established that peptic ulcer disease, chronic gastritis, and gastric malignancies are strongly related to Helicobacter pylori (H. pylori) infection. H. pylori has been identified by the WHO as a dangerous carcinogen (1). In addition, H. pylori plays a leading role in gastritis, which can result in gastric cancer (2,3). The incidence of gastric cancer was significantly reduced when H. pylori was eradicated in infected Asian individuals who were asymptomatic and healthy (4). Researchers have also found that infection with H. pylori can result in cardiovascular, hematological, hepatobiliary, and metabolic diseases (5–9). Currently, many epidemiological surveys have been performed to identify risk factors for H. pylori infection; age, obesity, and type 2 diabetes mellitus have been identified as risk factors (10–13). In terms of diagnosis, stool antigen testing, gastric biopsies, CLO-test, and urea breath test are used. However, 13C-urea breath test is the best known and most widely used test for detecting the presence of H. pylori infection and showed excellent accuracy compared to histology (14,15). According to previously published studies on the prevalence of H. pylori infection in China, the rates ranged from 41.35% to 72.3% and varied among different populations and different geographic areas (16). However, similar studies that focused on southwest China, such as in Chongqing, have rarely been performed. We studied a cohort from Chongqing, China. We used a 13C-urea breath test to analyze the prevalence of H. pylori infection and explore the potential risk factors for H. pylori infection in this population. It is our hope that our study may contribute to the current knowledge on the prevention and management of H. pylori infection.

2. Materials and methods

The study was carried out at the medical examination center in the First Affiliated Hospital of Chongqing Medical University, China in 2014. The study was approved by the Research Ethics Committee of the First Affiliated Hospital of Chongqing Medical University, and informed consent was obtained from each participant.

2.1. Study subjects and medical examination

The data in this study were collected from January to December 2014. Participants enrolled in this study were healthy subjects aged 18 years or older who received annual medical examinations. Participants with malignant tumors, severe cardiovascular diseases, acute infection, endocrine diseases, or incomplete data were excluded, accounting for 239 subjects. The final sampling size was 10,912. All participants received physical examinations and laboratory tests. The heights and weights of subjects were measured in a fasting state; the systolic and diastolic blood pressures (SBP and DBP) were measured twice with a standard apparatus during the medical examinations. Venous blood samples were collected following an overnight fast. Fasting blood sugar (FBS), serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), fasting serum triglycerides (TGs), albumin, highdensity lipoprotein cholesterol (HDL-C), γ-glutamine transferase (γ-GT), alanine transaminase (ALT), and aspartate aminotransferase (AST) were measured using an automatic biochemical analyzer (AU5400, Olympus, Tokyo, Japan).

2.2. Case definition H. pylori status was measured via 13C-urea breath test.

As previously described, the 13C- urea breath test was performed using standard procedures (17). In brief, a baseline breath sample was collected, and then the subject drank a test solution containing 75 mg 13C-urea. The 13CO2 in the breath was measured after 30 min. The breath samples were analyzed with an infrared heterodyne radiometer. If the two values showed a difference greater than 0.4%, then he/she was confirmed as being infected with H. pylori. Otherwise, he/she would be declared free of infection. Hyperglycemia was defined as fasting blood sugar ≥6.1 mmol/L. Body mass index (BMI) was defined as weight divided by height squared (kg/m2 ). According to the Chinese guidelines for the prevention and control of obesity, BMI <24 kg/m2 was considered normal BMI, BMI ≥24 kg/m2 was considered overweight, and BMI ≥28 kg/m2 was considered obese. Waist circumference was measured at the midway point between the costal margins. The waist-to-height ratio (WHtR) was calculated by waist circumference/height; WHtR ≥ 0.5 was considered central obesity. Subjects were also divided into groups based on serum albumin (g/L) quartiles (Qs): Q1 <45, Q2 45–47, Q3 47–48, and Q4 ≥48. Low albumin was defined as the lowest quartile of albumin (≤45 g/L). According to the joint committee for developing Chinese guidelines on the prevention and treatment of dyslipidemia in adults formulated in 2007, serum TGs ≥2.26 mmol/L were defined as high TGs, and HDL-C <1.04 mmol/L was considered low HDL-C. Serum TGs ≥6.22 mmol/L or LDL-C ≥4.14 mmol/L were defined as hypercholesterolemia.

2.3. Statistical analysis

All statistical analyses were performed with SPSS v.20.0 (SPSS Inc, Chicago, IL, USA). Variables distributed normally are presented as mean ± SD, while variables with a skewed distribution are presented as medians (interquartile range). The significance of differences between two groups was determined with a Student’s t-test for continuous data following a normal distribution. A Wilcoxon rank sum test was used for skewed distribution data and a chi-square test was used for dichotomous data. Logistic regression was performed to identify risk factors for H. pylori infection. Statistical differences were defined by P values (2-tailed) less than 0.05.

3. Results

The baseline characteristics of all subjects are shown in Table 1. The prevalence of H. pylori was 34.4% (3750/10,912); 33.8% and 35.1% in males and females, respectively. Of the 10,912 participants, 5774 (47.1%) were male and 5138 (52.9%) were female. The mean age was 44.1 ± 10.8. The mean age of the H. pylori-infected subjects was older than H. pylori-negative subjects. In the H. pylori-infected group, TC, LDL-C, and FBS were higher while albumin was lower, with each of these differentials reaching statistical significance (P < 0.05). However, BMI, WHtR, SBP, DBP, γ-GT, ALT, AST, TGs, and HDL-C did not differ significantly. 3.2. Logistic regression for H. pylori with its risk factors and prevalence of H. pylori infection among the risk factors We further analyzed the risk factors for H. pylori infection. As shown in Table 2, for univariate logistic regression analysis, H. pylori infection was significantly associated with older age, low albumin, high total cholesterol, high LDL-cholesterol, and hyperglycemia. After adjusting for other confounding factors, results showed older age (35– 45: 1.343, 95% confidence interval 1.021–1.765; ≥45: 1.610, 95% confidence interval 1.228–2.111), low albumin (1.136, 95% confidence interval 1.031–1.251), and hyperglycemia (1.258, 95% confidence interval 1.103–1.434) remained as statistically significantly associated with risk factors for H. pylori infection (Table 3).

Meanwhile, we analyzed prevalence of H. pylori infection among each risk factor. As shown in Table 4, the prevalence of H. pylori infection increased with increasing age; 26.0% of infected subjects were <25 years old, 29.7% were 35–44 years old, and 32.8% were ≥45 years old. Subjects with hyperglycemia had a higher rate of infection without considering sex differences. Low albumin was associated with a higher incidence for H. pylori infection.

4. Discussion

The rates of H. pylori infection have significantly decreased in developed Western countries, but the situation is less well-defined in developing countries like China. In this study, we aimed to investigate the prevalence of H. pylori infection and explore the potential risk factors for H. pylori infection. Our results showed that the prevalence of H. pylori infection was 34.4% in Chongqing. The results of this study also showed that older age, hyperglycemia, and low albumin are independent risk factors for H. pylori infection in the population from southwest China. Age plays an important role in infection among the elderly. However, previous studies have shown ambiguous associations between H. pylori infection and age. Tarkhashvili et al. showed that H. pylori infection was associated with older age, and they attributed the higher infection rate to lower socioeconomic conditions (18). A study that aimed to explore associations between H. pylori infection and metabolic syndrome also showed a higher prevalence in older age groups (19). Another study, however, showed that the elderly had a relatively lower infection rate (10). In our study, the prevalence of H. pylori infection increased along with increasing age, and age was an independent risk factor for H. pylori infection. On one hand, adults who had relatively poor childhood living conditions experienced higher rates of H. pylori infection; the infection persisted throughout life unless specific measures were taken (20,21). On the other hand, although H. pylori infection was highly prevalent, only 10%–20% of infected people became symptomatic, which leads to lack of accurate measures for eradication (22). Both factors may have resulted in a cumulative effect in the older group and thus a higher prevalence in the elderly. However, further studies are needed to understand the associations between age and H. pylori infection. The main physiological function of serum albumin is to maintain the colloid osmotic pressure and as a marker for liver synthetic function. In our study, we found a significant association between low serum albumin and H. pylori infection. Our data showed that the group with serum albumin ≥48 g/L had the lowest rate of infection, while the group with serum albumin <45 g/L had the highest rate of infection. However, there is ambiguity in the current published literature about the pathophysiologic relationship between serum albumin and H. pylori infection. The mechanisms might involve declining physiologic functions in the elderly and compromised liver synthetic function, which resulted in low serum albumin; low serum albumin was shown to be linked to infection and longer duration of hospitalization (23,24). Furthermore, previous studies have shown that albumin has important immunomodulation and anti-inflammatory activities (25). Infusion of albumin had positive effects in patients suffering from infection (26,27). Those results indicate that the subjects with low albumin are more likely to be infected with H. pylori. As demonstrated previously, some reports have shown that there is a significantly higher infection rate and lower eradication rate among subjects with diabetes mellitus (11,28,29). In the present study, hyperglycemia has been shown to be a significant risk factor for H. pylori infection. Although the pathological mechanism is unclear, available findings can partially explain the potential mechanisms through which hyperglycemia can lead to higher rates of H. pylori infection. Hyperglycemia has been shown to increase endothelial permeability and alter basement membrane composition and structure (30,31), making it easier for H. pylori infection to occur. Meanwhile, a study from Shew-Meei Sheu’s group also showed that hyperglycemia played a positive role in maintaining H. pylori growth and viability and enhancing bacterial adhesion (32). Some results of the present study appear to be discordant with expected patterns. The prevalence of H. pylori infection was 34.4% in Chongqing at the time of this study, similar to our previous study (33). However, it was much lower than previously published studies (16). Several reasons may contribute to the differences. First, a previous study showed that H. pylori infection was significantly and inversely associated with socioeconomic status (34). The subjects in this study who had a health check-up in third-level Grade A hospitals had a relatively better income, which might have resulted in the lower rates of H. pylori infection in this study. Secondly, identification of the presence of H. pylori infection was obtained via different methods, and some of the tests for H. pylori may have resulted in a higher false-positive rate than the urea breath test. Previous studies have shown that H. pylori infection was associated with high BMI, lower HDL cholesterol, sex differences, higher levels of blood pressure, and total cholesterol (35,36). However, we did not find an association between the above-mentioned factors and H. pylori infection in this study. The reasons may be that the populations enrolled in different studies may have had different characteristics and genetic backgrounds, different inclusion criteria, different cultural traditions or eating patterns, or were from different geographic regions. Those factors need to be investigated further. We must acknowledge that there were limitations in this study. First, we did not collect information on the use of drugs for H. pylori infection treatment before the 13C-urea breath test examination and excluded the subjects with a history of antibiotic use for H. pylori infection, which might have led to underestimation of the prevalence of H. pylori infection. Second, although we had a large population, the analysis was based on data from only one center and there was limited information on the subjects. A multicenter study and additional information such as education status, smoking, number of people in household, alcohol intake, socioeconomic status, and quality of water supply should be collected to reduce bias and validate the results in this study. Finally, because this was a cross-sectional design, the association between the potential risk factors and infection with H. pylori could not be proven conclusively. Longitudinal studies should be carried out to confirm the results before extrapolating them to other areas. In conclusion, our study showed that the current infection rate of H. pylori was 34.4% in Chongqing. We also showed that older age, low albumin, and hyperglycemia were independent risk factors for H. pylori infection. However, further studies are needed to further identify the risk factors that will be helpful in developing strategies for the prevention of H. pylori infection. Acknowledgment The authors are grateful to the examination center at the First Affiliated Hospital of Chongqing Medical University for data collection.

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Last modified on Thứ hai, 05 Tháng 10 2020 10:19
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