C A Malcolm, W G MacKay*, A Shepherd, L T Weaver*
Department of Nursing and Midwifery, University of Stirling, Stirling,
Division of Developmental Medicine, Department of Child Health, University of Glasgow
Correspondence to: Professor Lawrence Weaver, Division of Developmental Medicine (Child Health), Royal Hospital for Sick Children, Yorkhill, Glasgow G3 8SJ
SMJ 2004 49(4): 136-138
Background and Aims: To examine the association between prevalence of H. pylori colonisation and social deprivation in a sample of children investigated in hospital. Methods: A retrospective review of the hospital records of all children (n=626) who underwent 13C-urea breath testing for suspected H. pylori infection at the Royal Hospital for Sick Children, Glasgow, Scotland between August 1995 to December 2002 was performed. Prevalence of H. pylori colonisation was measured by the 13C-urea breath test and socioeconomic status was measured by the Carstairs and Morris index of deprivation. Results: The overall prevalence of H. pylori was 26%. There was a highly significant positive association between H. pylori colonisation and poor socioeconomic status (p < 0.0001). The prevalence of colonisation was significantly higher in children from the most deprived areas (DepCat 6 and 7; 34%) compared to children from intermediate (DepCat 3 to 5; 22%) and the most affluent areas (DepCat 1 and 2; 16%) (p < 0.0001).
Conclusions: Socioeconomic deprivation in childhood is associated with a high prevalence of H. pylori colonisation. While the incidence of H. pylori may be declining, it remains common in poor families. If the prevalence of H. pylori (26%) in this selected group reflects that of the population at large, then over 9000 (5%) of Glasgow’s children are at risk of this preventable disease. In a city where the majority of adults are colonised with H. pylori, colonisation in early life adds to the burden of health risks to which deprived children are exposed.
Key words: Helicobacter pylori, children, prevalence, socioeconomic status
Helicobacter pylori is the commonest chronic bacterial infection of mankind.1 It is the principal cause of chronic gastritis and peptic ulcer disease2 and is a risk factor for gastric cancer.3 In children H. pylori is associated with diarrhoeal disease, malnutrition,4,5 and growth retardation6 or faltering.7 The prevalence of H. pylori is highest in communities of low socioeconomic status,7-11 with poor hygiene,12-13 and overcrowded living conditions.9-12 In the developing world the prevalence of H. pylori is high and the majority of children are colonised before they reach adolescence,14 usually during the preschool period.15-16 In the developed world the incidence of H. pylori appears to be declining, and a ‘cohort effect’ has been suggested as accounting for this.17 Glasgow, a large city characterised by many areas of low socioeconomic status, appears to be an exception to this pattern with a prevalence of 66% in adults.18 We aimed to examine the prevalence of H. pylori colonisation in children living in Greater Glasgow according to their socioeconomic status, and to predict its long-term consequences on their health.
The study protocol was approved by the Royal Hospital for Sick Children’s Research Ethics Committee. Records of all children who underwent a 13C-urea breath test urea breath test for investigation of gastrointestinal symptoms at the Royal Hospital for Sick Children, Glasgow, between August 1995 and December 2002 were stored on a database. From this information each child’s age at testing, gender, postcode, and H. pylori status (positive or negative 13C-urea breath test) was extracted and analysed. The 13C-urea breath test was performed after an overnight fast. A baseline breath sample was obtained by asking the child to blow gently through a straw into an Exetainer. The dose of urea (100 mg 13C urea) (Torbett Laboratories Limited, Norwich) was dissolved in one heaped teaspoon of Polycose (Ross Products Division, Abbott Laboratories, Queenbourgh, Kent) and added to a glass of cold water flavoured with sugar-free fruit flavoured concentrate. Breath samples were obtained at 30 and 45 minutes after consumption of the dose of urea. The abundance of 13C in breath CO2 was measured by continuous-flow isotope ratio mass spectrometry. The breath test was considered positive, and thus diagnostic of H. pylori colonisation, if the enrichment of the post-dose breath sample was greater than or equal to 40 parts per million 13C above the fasting baseline.19
Socioeconomic status was classified using the Carstairs and Morris Index of Deprivation, which is often used in Scotland as a measure of socioeconomic deprivation.20 Four census variables representing material disadvantage (proportion of households with male unemployment, lack of car ownership, overcrowded housing and the head of household being in social class IV or V) were used to compute a deprivation score for each postcode sector in Scotland. There are seven deprivation scores or categories (DepCat) with DepCat 1 being the most affluent and DepCat 7 being the most deprived. A DepCat was assigned to each child using his/her postcode of residence at the time of the urea breath test.
The association between prevalence of H. pylori infection and age and gender was analysed using the Chi-square test, and with socioeconomic status using the Kendall’s Tau test. All statistical analyses were performed using SPSS for Windows (version 11.0; SPSS Inc., Chicago IL, U.S.A.).
Between August 1995 to December 2002, 626 children (320 females, 306 males) aged 2 to 16 years (median 10) underwent a 13C-urea breath test for investigation of gastrointestinal symptoms.
A positive urea breath test, indicating current H. pylori colonisation, was recorded in 164 of the 626 children (26.2%). The prevalence of H. pylori was not associated with age (÷2=15.2, p=0.36) and did not differ significantly between genders (÷2=0.11, p=0.74) (Table I).
Postcodes were available for all 626 children and were used to assign a DepCat score to each child. There was a significant positive association between DepCat and prevalence of H. pylori (Kendall’s tau-b=0.15, p< 0.0001). The prevalence of H. pylori was significantly higher in children from the most deprived areas (DepCat 6 and 7; 34%) compared to children from intermediate (DepCat 3 to 5; 22%) and the more affluent areas (DepCat 1 and 2; 16%) (Kendall’s tau-b=0.14, p<0.0001) (Fig 1).
While this high prevalence in a selected group of children is not a true measure of the overall childhood population prevalence, it indicates that the greatest prevalence of H. pylori is in the most deprived children. In Scotland, 18.8% of children live in DepCat areas 6 and 7. Within Greater Glasgow, 53% of children live in DepCat areas 6 and 7.21 The distribution of DepCats in our study sample reflects this pattern, with 284 of the 626 (45%) subjects residing in DepCats 6 and 7. While H. pylori may be disappearing in parts of the world where living conditions, population density, sanitation and hygiene have improved, it remains widespread in poor families in Glasgow. This is a concern because of the implications for the health of children. Acquisition of H. pylori infection during childhood may be a risk factor for ulcer disease(22) and the development of gastric carcinoma23 in adult life. Colonisation with H. pylori infection confers a 10-20% lifetime risk of developing peptic ulcer disease.22 The population of children, aged 16 years and younger, living in the Greater Glasgow area is 176 325.24 If it were to be assumed that the prevalence of H. pylori (26%) in this selected sample of children reflects that of the population at large, then 5% of children (around 9000) in Greater Glasgow are at high risk of developing ulcer disease. There is strong evidence that children acquire H. pylori from their parent25 or colonised siblings.26 A retrospective population study of childhood living conditions and adult mortality in 5646 men in the west of Scotland reported a positive association between stomach cancer and childhood socio-economic status and suggested that H. pylori infection in early life was the most likely cause.27
In Glasgow the prevalence of H. pylori is 70-80% in lower occupational social classes, and most marked in middleaged men and women(18). In 25-34 year olds the prevalence was over 50%, and our data extend these figures back into childhood. Glasgow is not the only city characterised by poor socioeconomic conditions and poverty in which a high prevalence of H. pylori has been reported in children. In Belfast, children whose parents were engaged in manual work and were of low socioeconomic status were significantly more likely to be H. pylori positive(10).
The socioeconomic circumstances into which children are born and subsequently raised are major determinants of their future health. Glasgow and the west of Scotland have high levels of deprivation and this is reflected in poorer health such as increased rates of coronary heart disease and lung cancer observed in individuals living in the most deprived areas(21). The strong positive relation between H. pylori colonisation and poor socioeconomic status adds H. pylori to the list of diseases to which children in deprived communities are exposed. Because H. pylori is a chronic infection, a cause of ulcer disease and a risk factor for gastric cancer, our findings emphasise the need to combat childhood poverty and improve the domestic and socio-economic conditions is which children live.
ACKNOWLEDGEMENTS: We acknowledge Christine Slater for designing and maintaining the UBT database. We thank the children and parents for their assistance with this study.
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