RISK FACTORS FOR REINFECTION WITH HELICOBACTER PYLORI.

105 H.pylori infection of the gastric mucosa is associated with chronic gastritis, duodenal ulcer disease, and gastric cancer. H. pylori infection is almost always acquired in childhood. Risk factors for primary infection include poor socio-economic conditions and overcrowding. We have recently shown that that reinfection with H. pylori following treatment occurs rarely in children over 5 years of age, but frequently in those under 5 years. Aim: Identify if specific risk factors are associated with reinfecton following treatment. This should help to determine if it is necessary to treat family members to achieve long-term eradication ofH. pylori. Methods Fifty two children were followed prospectively to determine the risk factors for reinfection. Information on family size, socio-economic status, overcrowding, and sleeping arrangements were documented. Infection among family members was assessed using a13 C-urea breath test. Cox logistic regression as implemented by SAS(SAS Institute Incorporated, Cary, NC.) was used to estimate relative risks of reinfection. Forward stepwise methods determined which factors were independently and significantly related to reinfection. Results: Among 52 children (mean age 11.1 yrs SD 4.4) reinfection occurred in 11.5% but in only 4.3% of children over 5 years of age. 94% of index children had at least one parent and 61.5% had both parents infected. Almost 68% of siblings of index children were infected. 54% of families were from lower social classes and 30% lived in overcrowded conditions. In a univariate analysis lower SEG (RR=6.0 95%CI 0.7 -51.2) and having both parents currently infected(RR = 4.5 95%CI 0.5-38.6) did not reach statistical significance as risk factors for reinfection. Sharing a bed with a parent or sibling (RR = 7.2 95%CI 1.3-39.6) or having more than 2 older infected siblings (RR= 7.1 95% CI 1.4-35.1) were the only factors which reached statistical significance. However using a stepwise forward regression (Table) age was the only factor to have a significant and independent relationship with reinfectionConclusions. Poor socio-economic conditions and a high prevalence of infection among family members are not risk factors for reinfection in children. Age is the only significant risk factor for reinfection in children. This suggests that if possible treatment should be confined to children over 5 years, and it is not necessary to treat all family members to prevent reinfection.