1 Dr Liam Murray, The Queens University of Belfast, Belfast BT12 5BJ, UK.
2 The Royal Group of Hospitals Trust. Grosvenor Road, Belfast BT12 6BJ, UK.
3 Department of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, UK.
4 University of East Anglia, School of Health Policy and Practice, Norwich NR4 7TJ, UK.
5 Peterborough District Hospital, Thorpe Road, Peterborough PE3 6DA, UK.
6 Frenchay Hospital, North Bristol NHS Trust, Bristol BS16 1LE, UK.
Correspondence: Dr Liam Murray, The Queens University of Belfast, Mulhouse Building, The Royal Group of Hospitals, Grosvenor Road Road, Belfast BT12 6BJ, UK. E-mail: l.murray{at}qub.ac.uk
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Abstract |
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Design and setting Cross-sectional population-based study, as part of a randomized controlled trial of eradication of Helicobacter pylori infection, in Southwest England.
Subjects In all, 10 537 subjects, aged 2059 years, were recruited from seven general practices. Subjects provided data on frequency and severity of dyspeptic symptoms and anthropometric measurements were taken.
Main outcome measure Relationship between overweight (body mass index [BMI] 25 kg/m2 and
30 kg/m2) or obesity (BMI >30 kg/m2) and frequency and severity of heartburn and acid regurgitation.
Results Body mass index was strongly positively related to the frequency of symptoms of gastro-oesophageal reflux. The adjusted odds ratios (OR) for frequency of heartburn and acid regurgitation occurring at least once a week in overweight participants compared with those of normal weight were 1.82 (95% CI: 1.332.50) and 1.50 (95% CI: 1.131.99) respectively. Corresponding OR (95% CI) relating to obese patients were 2.91 (95% CI: 2.074.08) and 2.23 (95% CI: 1.443.45) respectively. The OR for moderate to severe reflux symptoms were raised in overweight and obese subjects but not to the same extent as frequency of symptoms and only the relationship between obesity and severity of heartburn reached conventional statistical significance: OR = 1.19; 95% CI: 1.071.33.
Conclusions Being above normal weight substantially increases the likelihood of suffering from heartburn and acid regurgitation and obese people are almost three times as likely to experience these symptoms as those of normal weight.
Accepted 4 February 2003
A recent report has drawn attention to the lack of robust information on the relationship between body mass and gastro-oesophageal reflux disease (GORD) and has highlighted the inconsistency in the findings of studies published in this field.1 Clinical studies involving oesophageal pH monitoring show both positive2 and negative3 associations between body mass and gastro-oesophageal reflux, and weight reduction is not consistently related to improvement in symptoms.4,5 Such studies have been conducted mainly in morbidly obese patients attending secondary or tertiary care, but evidence from population-based studies is also conflicting,1,68 which has led to claims that weight reduction may have no effect on the symptoms of GORD,1 a view which is disputed.9
The relationship between weight and gastro-oesophageal reflux is an important one, not just because of the implications for treatment of symptomatic individuals, but also because both body mass10,11 and history of reflux12,13 have been shown to be important risk factors for oesophageal adenocarcinoma. The incidence of this cancer has been reported to have increased substantially in several developed countries in recent decades, mainly in white Caucasian populations.14,15 If high body mass is a causal risk factor for GORD, trends in overweight and obesity in these populations16,17 indicate that the incidence of this cancer may continue to rise.
To date no population-based study of the relationship between body mass and symptoms of GORD has been undertaken in the UK and only a few such studies have been performed in other countries.1,68,18,19 We examined this relationship within the population-based Bristol Helicobacter Project.
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Methods |
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Participants underwent 13C urea breath testing and their blood pressure and height and weight (after removing heavy outdoor garments) were measured. Subjects also completed a self-administered questionnaire that gathered information on the frequency and severity of dyspeptic symptoms (heartburn, acid regurgitation, epigastric pain/discomfort, a feeling of wind/fullness, belching and burping, and nausea) relating to the 3 months prior to examination. Heartburn was defined as a burning or ache behind the breast bone that is not due to heart trouble and acid regurgitation as a very sour or acid tasting fluid at the back of your throat. Data on self-medication and prescription-only medicines were also collected, including use of anti-dyspeptic medications, painkillers, aspirin, and non-steroidal anti-inflammatory drugs (NSAID). Lifestyle information was collected in the questionnaire and included smoking history (never smoker, ex smoker, current smoker <20 cigarettes a day, current smoker 20 cigarettes a day), alcohol intake (units of beer, wine and spirits per week, combined), coffee consumption (cups per day) and measures of adult socioeconomic status (occupation manual, or non-manual), highest educational qualification, tenure of accommodation (rented or owned), and number of cars in the household). This study includes data relating to all participants who tested positive for H. pylori infection and a computer-generated random sample of H. pylori-negative subjects to give an H. pylori negative to positive ratio of 2:1.
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Statistical analysis |
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Bivariable relationships between BMI and frequency or severity of heartburn and acid regurgitation were assessed using 2 tests. In order to determine the specificity of the observed relationships between BMI and heartburn and acid regurgitation, the relationship between BMI and frequency of other dyspeptic symptoms were also assessed using
2 tests and these analyses were stratified by frequency of heartburn and acid regurgitation. Similarly, the bivariable tests of the relationships between frequency of heartburn and acid regurgitation were stratified by frequency of other dyspeptic symptoms.
The relationships between BMI and the frequency or severity of heartburn and acid regurgitation were further assessed using multivariate logistic regression modelling (Stata version 7, College Station, Texas, USA). Models were constructed with frequency or severity of reflux and acid regurgitation as the dependent variables and BMI as a categorical predictor variable, with adjustment for potential confounding by age group, sex, smoking, alcohol intake, coffee consumption, active H. pylori infection, measures of adult socioeconomic status, and the use of painkillers, aspirin, and NSAID. The clustered nature of the data (by general practice) was accounted for by defining the general practice at which participants were registered as the primary sampling unit in the logistic regression models. Weighted analyses were performed because of the increased sampling of H. pylori subjects (33% of subjects included in the database, but 15.5% of all subjects screened). The weights used were proportional to the inverse of the sampling fractions.
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Results |
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The frequency and severity of heartburn and acid regurgitation are shown in Table 1. Half of the participants had not experienced heartburn in the previous 3 months and almost 60% had not had acid regurgitation in the same period. Of all the participants, 13.4% had heartburn, and 8.2% acid regurgitation, at least once a week in the previous 3 months. Frequency of heartburn and acid regurgitation were associated: 97.0% of the 4002 participants who did not have heartburn at least once a week also did not have acid regurgitation this frequently, while 42.6% of the 643 participants who experienced heartburn at least once a week also had acid regurgitation at least once a week (
2 1112, d.f. 1, P < 0.0001).
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Table 3 shows the unadjusted and adjusted relationships between BMI category and frequency and severity of symptoms of gastro-oesophageal reflux. Following adjustment for potential confounders, BMI remained strongly and linearly positively related to frequency of symptoms of gastro-oesophageal reflux. The odds ratios (OR) for frequency of heartburn and acid regurgitation occurring at least once a week in overweight participants compared with those of normal weight were 1.82 (95% CI: 1.332.50) and 1.50 (95% CI: 1.131.99) respectively. Corresponding OR relating to obese patients were 2.91 (95% CI: 2.07 4.08) and 2.23 (95% CI: 1.443.45) respectively. The OR for moderate to severe reflux symptoms were raised in overweight and obese subjects but not to the same extent as frequency of symptoms and only the relationship between obesity and severity of heartburn reached conventional statistical significance: OR = 1.19; 95% CI: 1.071.33. In the multivariable models, age group, sex, social class (manual versus non-manual), and active H. pylori infection were not associated with frequency or severity of symptoms. Alcohol intake remained associated with frequency of heartburn but smoking and use of painkillers, aspirin, and NSAID remained consistently positively related to both frequency and severity of heartburn and acid regurgitation. However, the strongest relationships observed were for overweight and obesity. Sex-specific multivariate models were also constructed and the associations between overweight/obesity and frequency and severity of heartburn and acid regurgitation did not differ between the sexes.
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Discussion |
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In our study, being overweight or obese were strongly related to the frequency of heartburn and acid regurgitation, independently of potential confounding variables (including other dyspeptic symptoms). Obese subjects had heartburn almost three times more frequently than had subjects of normal weight. This positive association between body mass and gastro-oesophageal reflux is clearly biologically plausible as there are several important pathophysiological mechanisms linking body mass and reflux. Oesophageal transit in obese reflux patients is slower than in their leaner counterparts,23 BMI is associated with the development of a hiatal hernia24,25 (an important factor in delaying the clearance of acid from the oesophagus26), and there is evidence that increasing BMI increases intra-abdominal pressure,27 although this may be counteracted by equivalent increases in lower oesophageal sphincter pressure.28
Our findings are in keeping with three other cross-sectional questionnaire/interview-based studies in this field.68 A recently published study involving Korean subjects undergoing upper gastro-intestinal endoscopy as part of a routine health check also demonstrated a positive relationship between BMI and reflux oesophagitis.18 Follow-up of 12 500 subjects in the First National Health and Nutrition Examination Survey (NHANES I) for almost 20 years also showed that hospitalization for gastro-oesophageal reflux disease was related to BMI.19 However, it is possible that overweight or obesity per se may have been a factor influencing admission to hospital with GORD. These population-based studies add to data from investigations in clinical populations undergoing upper gastrointestinal endoscopy. Although such studies may be open to selection and detection biases1 they provide evidence, from a number of countries, that endoscopically-diagnosed oesophagitis is more common in overweight or obese patients.24,25,29
The failure of Lagergren et al.1 to find an association between body mass and gastro-oesophageal reflux is clearly at odds with most literature in this field. Their negative result was observed among the controls of a case-control study of oesophageal adenocarcinoma. These controls were frequency matched with cases and therefore represent a small section of the general population, principally elderly males. Furthermore, the calculated BMI was not concurrent with the period of reporting of gastro-oesophageal symptoms, which related to 5 years before the date of interview.
On the basis of our study and others it appears that being above normal weight substantially increases the likelihood of suffering gastro-oesophageal reflux symptoms. It may follow that weight reduction will decrease the occurrence of these symptoms30,31 but a more robust evidence base is required upon which to base clinical recommendations of weight loss in patients with GORD. The strong positive association we have demonstrated between body mass and symptoms of gastro-oesophageal reflux also has relevance for the general population. Trends in overweight and obesity in western populations,16,17 are set to substantially increase, in coming years, the proportion of the population experiencing gastro-oesophageal reflux disease. There are many reasons why an increase in the prevalence of overweight and obesity holds trouble in store for public health and the provision of health services. To these must be added the costs of managing symptoms of gastro-oesophageal reflux and given the association between body mass, symptoms of reflux, and risk of oesophageal adenocarcinoma,1013 further increase in this, once uncommon, cancer seems likely.
KEY MESSAGES
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Acknowledgments |
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References |
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