Assessment of prevalence and risk factors of helicobacter pylori infection in an oilfield Community in Hebei, China

This was a cross-sectional study carried out in Jidong Community of Hebei province, China. This community included 10,043 employees of the Jidong Oilfield Inc. and their families. From June 2016 to June 2017, all residents took physical examination in the Caofeidian District Hospital. Six thousand six hundred fifty-six subjects agreed to participate this study and completed a structured questionnaire. One thousand eight hundred sixty subjects were excluded from the study. The exclusion criteria were as follows: 1. Past history of gastric cancer, coronary heart disease (CHD) or ischemic stroke (IS) as assessed by a validated questionnaire; 2. Previous gastrectomy; 3. On antibiotics during past 30 days or any proton pump inhibitors within 14 days before. Finally, a total of 4796 consecutive subjects were enrolled and subsequently had ¹³C-urea breath test (13C-UBT).

The study protocol was reviewed and approved by the Ethics Committee of Jidong Oilfield Inc. Medical Center and Beijing Friendship Hospital, Capital Medical University. The approval will be renewed every 5 years. We got written informed consent from all participants.

All subjects were invited to finish a structured questionnaire under the guidance of a well-trained interviewer (Additional file 1). The questionnaire captured the information regarding demographic and socioeconomic characteristics (i.e., age, sex, marital status, BMI, TC, TG, and fasting glucose, education level, source of drinking water, household population, Household hygiene, household surrounding environment and household area per capita), personal habits and knowledge about H. pylori (i.e. cigarette smoking, alcohol drinking, intake of raw garlic, raw vegetables, fried foods and pickled foods, hand washing before meals and after toilet use, staying up at night, peeling fruits, raising domestic animals, sharing cutlery or cups, eating by individual serving), and medical history (i.e. chronic gastritis, gastric ulcer, duodenal ulcer, chronic cholecystitis and cholelithiasis, previous gastroscopy, family history of GI cancer, hypertension, diabetes mellitus, hyperlipidemia). Body mass index (BMI) was classified into 3 grades: normal status (≤25 kg/m2), overweight (25 kg/m² to 30 kg/m²), and obesity (≥30 kg/m²) [8]. We defined the condition of household hygiene as good if the participant or his/her families can clean their house once per day, as intermediate if per week, as bad if more than 1 week. Household surrounding environment was referred to as good if public trash cans can be cleared more than twice per day, as intermediate if once per day, as bad if only cleared once every 2 days or even longer.

After obtaining informed consent from participants the status of H. pylori infection would be assessed using ¹³C-UBT which was undertaken after at least 6 h of fasting. The ¹³C-UBT was performed using 75 mg of ¹³C-urea dissolved in 100 mL of drinkable water. Breath samples were collected before and 30 min after drinking water. Then they were analyzed using a nondispersive infrared spectrometer (HY-IREXB, Hua You Scientific, China). We regarded the result as positive when the value was equal to or higher than 4 ± 0.4. Certain subjects with positive results would be advised to eradicate H. pylori.

The baseline characteristics of participants with or without H. pylori infection were compared, using the chi-square test for categorical variables and the two-sample t-test for continuous variables. The trend of H. pylori infection rate in different age groups was analyzed by chi-square trend test. A P-value of <0.05 was considered to be statistically significant. Odds ratios (OR) and 95% confidence intervals (CI) for the association between H. pylori infection and potential risk factors were estimated using multivariable logistic regression models. Variables were selected for entry into the regression model if the variables were significantly associated with H. pylori infection (p < 0.1) in the univariate analysis. All analyses were performed using SAS 9.3 (SAS Institute, Cary, North Carolina, USA).

The demographic features of 4796 subjects were summarized in Table 2. The mean age was 44.46 ± 13.45 years old, with 49.9%(n = 2392) being male (male-to-female ratio of 1:1.01). The majority of participants were currently married (4140/4796, 86.3%). More than half of the respondents had a high education level (university or above, 57.8%). The majority of them used barreled water as a main source of drinking water (56.0%). Nearly half of the population had household area per capita of 30–60 m² (44.2%) and the household population of middle size, good condition of household hygiene, good surrounding environment accounted for 90.1, 67.9 and 66.0%, respectively.

Minority of respondents reported a medical history of chronic gastritis (11.0%), gastric ulcer (3.6%), duodenal ulcer (2.2%), chronic cholecystitis and cholelithiasis (5.7%), hypertension (28.9%) and diabetes mellitus (9.0%), but nearly half of them reported hyperlipidemia (48.2%). Only 10.0% of the respondents had the previous gastroscopy, and 1.3% among respondents said a family history of gastrointestinal cancers (Table 3). Univariate analysis showed no significant differences across medical histories. (Ps > 0.5).

The overall prevalence of H. pylori was 52.25% (95% CI = 50.84–53.67%) in terms of the results of 13C-UBT from all subjects. The age-specific prevalence of H. pylori infection diagnosed by ¹³C -UBT is shown in Fig. 1 It illustrated a marked difference between age groups (P = 0.0045) and an increasing trend of prevalence with age (χ² test for trend = 23.5; P < 0.001).

It is depicted in Table 4 that there was no significant difference between both sexes (P = 0.5974) while different marital status showed significant difference in prevalence (P = 0.0243). Subjects who were currently married were more prone to be infected than those who were single. The prevalence of H. pylori was lowest (50.4%) when the educational level of the patient was highest, and there was a negative association between education level and H. pylori’s infection in general (χ² test for trend = 19.50; P < 0.001). Concerning the source of drinking water, subjects who used piped water were at higher risk for H. pylori infection than those who used barreled or bottled water (53.9% vs. 50.9%, P = 0.0433).

The proportion of the participants with normal anthropometric values included BMI < 25 kg/m² (60.5%), TC < 5.18 mmol/L (63.7%), TG < 1.7 mmol/L (59.8%) and Fasting Glucose<7.0 mmol/L (89.1%). For H. pylori positive and negative subjects, the mean value of BMI, TC, TG and fasting glucose were 24.59 ± 3.59 and 24.48 ± 3.67, 4.94 ± 0.96 mmol/L and 4.91 ± 0.94 mmol/L, 1.91 ± 1.61 mmol/L and 1.81 ± 1.34 mmol/L, 6.02 ± 1.33 mmol/L and 5.99 ± 1.30 mmol/L, respectively. No significant differences were obtained between subjects with and without H. pylori(Ps > 0.5).

No significant difference was obtained between smokers and non-smokers for H. pylori prevalence (P = 0.3375). However, patients who consumed alcohol had a higher prevalence of active H. pylori infection compared to non-drinkers (P = 0.0207). Subjects who never or seldom ate raw garlic had a lower H. pylori infection rate than those who ate often or every day (51.5% vs. 55.4%, P = 0.0310) (Table 4). Respondents who were familiar with the route of transmission and related diseases of H. pylori had a lower prevalence of infection than those who were unaware of (P = 0.0125, P = 0.0257, respectively).

Multivariate logistic regression analysis revealed that following factors were significant independent variables: age (P = 0.0024), alcohol drinking (OR = 1.139, 95% CI = 1.025–1.290, P = 0.0407) and knowledge about the route of transmission (OR = 0.796, 95% CI = 0.635–0.996, P = 0.0463). Respondents aged 41–50 (OR = 1.308, 95% CI = 1.088–1.573, P = 0.0043), 51–60 (OR = 1.460, 95% CI = 1.200–1.777, P = 0.0002) and over 60 years old (OR = 1.239, 95% CI = 1.021–1.502, P = 0.0296) were more likely to be H. pylori positive compared to those of 30 years old and below (Table 5).