Prevalence Of Helicobacter Pylori Infection In High-risk Area For Gastric Cancer: An All-ages Population-based Study

Background:The World Health Organization(WHO)has classified Helicobacter pylori(H.pylori)as a group I carcinogen associated with gastric cancer(GC).Its prevalence is higher in developing countries.This study aimed to determine the prevalence and risk factors of H.pylori infection across all age groups,the prevalence of upper gastrointestinal and hepatobiliary diseases in subjects over 18 years old in Wuwei City,Gansu Province,a high-risk area for GC in Northwest China.Methods:We conducted this study from 2016 to 2017 in an urban and a rural community in Wuwei City.We selected participants based on hierarchical cluster sampling.Stool antigen tests(SAT)targeted individuals aged 0 to 3 years old,¹³C-urea breath tests(¹³C-UBT)targeted individuals aged above 3 years old and serum anti-H.pylori Ig G antibodies tests targeted individuals aged above 6 years old.Questionnaires assessed sociodemographic variables,lifestyle,dietary patterns and other variables.Gastroscopy,biopsy,histopathology,and abdominal ultrasonography were performed on subjects over 18 years old.The prevalence of H.pylori infection,upper gastrointestinal diseases,precancerous lesions and partial hepatobiliary diseases were analyzed by descriptive statistics.The rates comparison was performed using chi-square test and Fisher exact probability and trend Chi-square test.We assessed the association between variables and H.pylori infection based on logistic regression models.Results:Ultimately,2,163 subjects(age:0-77 years)were enrolled,including 1,238 minors(57.2%)and 925 adults(42.8%);1,170 males(54.1%)and 993 females(45.9%);1,210 urban residents(55.9%)and 953 rural residents(44.1%).The overall prevalence of H.pylori infection in the study population was35.6%.The prevalence in minors and adults were 22.9%and 52.8%,respectively.The prevalence in male and female were 34.1%and 37.5%(P=0.104),respectively;the prevalence in urban and rural areas were 34.1%and 37.5%(P=0.671),respectively.The positive rate of serum anti-H.pylori Ig G antibodies in subjects aged above 6 years old was 49.3%.The positive rates in male and female were 44.5%and47.1%(P=0.01),respectively;the positive rates in urban and rural areas were 47.8%and 51.5%(P=0.679),respectively.The positive rate in subjects aged 7 to 18 years old was very close to the ¹³C-UBT results,but it was higher in adulthood than was seen in the ¹³C-UBT results by approximating 10%.The prevalence of H.pylori infection increased slowly with age until the subjects reached 12 years old.After that,it increased rapidly until reaching a peak in the 30 to 39 age group,and then began to decline slowly.The multivariate regression models have shown that the H.pylori infection of participants over 3 years old was positively associated with age(OR 1.30;95%CI1.23-1.37),while negatively associated with washing hand before meals and after using the toilet frequently or daily(OR 0.79;95%CI 0.60-1.03),drinking running water(OR 0.74;95%CI 0.56-0.97),consuming yoghurt frequently or daily(OR 0.80;95%CI 0.65-1.00),and an annual household income of Renminbi 3,0000-10,0000(OR 0.77;95%CI 0.62-0.96)or 10,0000 above(OR 0.63;95%CI 0.42-0.94).The same variables associated differently with H.pylori infection in different age groups,but the impact of socioeconomic variables,dietary patterns,and lifestyles on the prevalence of H.pylori infection was seen at all age groups.Age(OR 1.18;95%CI1.02-1.36),boarding(OR 1.72;95%CI 1.01-2.95),eating at school cafeterias with more than six times per week(OR 1.86;95%CI 1.12-3.09),and drinking untreated water frequently(OR 1.68;95%CI 1.00-2.81)were independent risk factors,while washing hands before meals and after using the toilet frequently or daily(OR 0.33;95%CI 0.16-0.67)and drinking running water(OR 0.43;95%CI 0.22-0.84)were independent protective factors for H.pylori infection in junior-senior high school students.The prevalence of atrophic gastritis(AG),non-atrophic gastritis(non-AG),reflux esophagitis,gastric polyp,duodenal bulbous inflammation and peptic ulcer(PU)diagnosed by gastroscopy was 68.6%,31.4%,14.2%,5.5%,4.0%and3.7%,respectively.The prevalence of non-AG,AG,intestinal metaplasia(IM),low-grade intraepithelial neoplasia diagnosed(LGIN)by histopathology were 44.2%,37.9%,12.7%and 4.7%,respectively;Only 3 cases of high-grade intraepithelial neoplasia(HGIN)and gastric carcinoma(GC)were diagnosed.The prevalence of non-AG in urban areas was significantly lower than that in rural areas(P=0.013).The prevalence of nonalcoholic fatty liver disease(NAFLD),gallstone, chronic cholecystitis,gallbladder polyp,liver and/or renal cyst,hepatic hemangioma diagnosed by abdominal ultrasonography were 26.6%,6.4%,6.4%,3.8%,9.4%,and4.1%,respectively.The prevalence of NAFLD in urban areas(31.7%)was significantly higher than that in rural areas(18.9%)(P<0.001).The prevalence of NAFLD in H.pylori positive group(22.1%)was significantly lower than that in H.pylori negative group(31.6%)(P<0.001).The prevalence of non-AG differed significantly between the H.pyloripositive and negative groups(39.0%VS 50.0%,P=0.008),as was AG(42.6%VS32.6%,P=0.013).The prevalence of IM and LGIN did not show the trend.In subjects with peptic ulcer,the ¹³C-UBT positive rate was 73.9%,and the positive rate of serum anti-H.pylori Ig G antibodies was 95.7%.The total prevalence of gallbladder diseases in the study population was16.6%,and there was no association between H.pylori infection and gallbladder diseases.Conclusion:The prevalence of H.pylori infection is moderate and increased slowly with age until the subjects reached 12 years old.After that,it increased rapidly until reaching a peak in the 30 to 39 age group,and then began to decline slowly.It closely associated with the socioeconomic conditions of Wuwei City,as well as the sanitary situations and dietary habits of the participants in the city.Never or occasionally washing hands before meals and after using the toilet,boarding,eating at school,and drinking untreated water mainly explained the rising infection rates in junior-senior high school students.The prevalence of precancerous lesions was very high,moreover,H.pylori infection played a crucial role in pathogenesis of precancerous lesions,especially from non-AG to AG.The prevalence of NAFLD,peptic ulcer and gallbladder diseases was high in Wuwei City.H.pylori infection may be a protective factor in the pathogenesis of NAFLD.