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R Liisa Jaakkimainen a Institute for Clinical Evaluative Sciences,
Department of Family and Community Medicine, Sunnybrook and Women's
College Health Sciences Centre, University of Toronto, Toronto,
Ontario, Canada M4N 3M5, b Inner City Health
Research, St Michael's Hospital, Toronto, Ontario, Canada M5B 1W8, c Department
of Family Medicine, Center for Evidence-Based Practice, State
University of New York Health Science Centre at Syracuse, NY 13210, USA
Correspondence to: R L
Jaakkimainen liisa.jaakkimainen{at}ices.on.ca
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Abstract |
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Objectives:
To examine the association between
Helicobacter pylori infection and non-ulcer dyspepsia, and
to assess the effect of eradicating H pylori on dyspeptic
symptoms in patients with non-ulcer dyspepsia.
Although drugs for acid suppression are the mainstay
empirical treatment for ulcer-like dyspeptic symptoms1-3
controversy surrounds the role of empirical eradication therapy for
Helicobacter pylori.
4 5
Although there is
strong evidence of an association between H pylori
infection, chronic gastritis, and peptic ulcer disease,
6 7
the relation between dyspeptic symptoms and
gastritis caused by H pylori is not well
described.
8 9
Systematic reviews examining the relation
between non-ulcer dyspepsia and H pylori have based their
conclusions on qualitative assessments of selected articles10-15 without any quantitative summary estimate
of an association. Only one estimate for H pylori infection
among patients with non-ulcer dyspepsia has been quoted in the
literature,16 but this was not based on a systematic
selection of articles, no sensitivity analyses of the estimate were
included, and there was no assessment for statistical heterogeneity.
If primary care strategies are to be developed for managing non-ulcer
dyspepsia or dyspeptic symptoms then evidence needs to be firmly
established for a relation between non-ulcer dyspepsia and H
pylori infection and for an improvement in dyspeptic symptoms with
eradication of H pylori.
We aimed to review the literature for both observational studies and
therapeutic trials. We also aimed to provide quantitative summary
estimates for an association between H pylori infection and
non-ulcer dyspepsia and for change in dyspeptic symptoms in patients
with non-ulcer dyspepsia in whom H pylori was eradicated.
Identification of studies
Design:
Systematic review and meta-analysis of
(a) observational studies examining the association between
Helicobacter pylori infection and non-ulcer dyspepsia
(association studies), and (b) therapeutic trials examining
the association between eradication of H pylori and
dyspeptic symptoms in patients with non-ulcer dyspepsia (eradication trials).
Data sources:
Randomised controlled trials and
observational studies conducted worldwide and published between January
1983 and March 1999.
Main outcome measures:
Summary odds ratios and summary
symptom scores.
Results:
23 association studies and 5 eradication
trials met the inclusion criteria. In the association studies the
summary odds ratio for H pylori infection in patients with
non-ulcer dyspepsia was 1.6 (95% confidence interval 1.4 to 1.8). In
the eradication trials the summary odds ratio for improvement in
dyspeptic symptoms in patients with non-ulcer dyspepsia in whom H
pylori was eradicated was 1.9 (1.3 to 2.6).
Conclusions:
Some evidence shows an association
between H pylori infection and dyspeptic symptoms in
patients referred to gastroenterologists. An improvement in dyspeptic
symptoms occurred among patients with non-ulcer dyspepsia in whom
H pylori was eradicated.
![]()
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
Conclusions
References
![]()
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
Conclusions
References
We conducted a Medline search of non-review articles in
English from January 1983 to March 1999 with the MeSH headings
"dyspepsia," "non-ulcer dyspepsia," "gastritis,"
"Helicobacter pylori," and "Campylobacter pylori."
Data extraction
We assessed the association studies with a modified version
of a quality assessment form for observational studies,17
and we assessed the H pylori eradication trials with an
existing quality assessment system for clinical trials.18 The methods sections were cut out and coded so that the assessors were
blind to the study results, title, authors, publication date, and
journal. Agreement between the assessors was evaluated with the
statistic.
19 20
Statistical analysis
We calculated an overall point estimate of the odds ratio
and 95% confidence interval with the Mantel-Haenszel statistic,21 which is based on the assumption of a fixed
effect model.22 Homogeneity was assessed with the
Breslow-Day method.23 The data were entered and analysed
with a statistical package.24
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Results |
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The review of abstracts identified 84 potentially eligible studies. Thirty five were eliminated because they did not satisfy the retrieval criteria. This left 26 articles dealing with the association between H pylori infection and non-ulcer dyspepsia (association studies) and 23 articles examining dyspeptic symptoms in relation to H pylori eradication therapy (eradication trials).
Observational association studies
Study characteristics and quality scores
Three studies did not provide information on H
pylori infection in the control group and could not be included in
the pooled analysis. The box summarises the study characteristics of
the 23 association studies (see website). Many studies defined non-ulcer dyspepsia as upper abdominal pain or discomfort with no
organic disease identified (16 studies) lasting more than 4 weeks.12 Most studies included patients with non-ulcer
dyspepsia referred to a specialty or gastroenterology
clinic16 and based the H pylori assessment
on the results of endoscopic biopsy.15 The rate of H
pylori infection in patients with non-ulcer dyspepsia was 55.2%
(range 9.4 (18.4) to 87.5) and in controls was 40.4% (range 4.7 (22.3)
to 83.3).
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Study characteristics (number of trials) of the 23 association
studies
Case selection Community based (3)w3 w6 w22 Random community sample (4)w7 w13 w21 w23 Control selection Hospital based (4)w4 w5 w11 w16 Outpatient based (2)w2 w17 Community based (13)w1 w3 w6 w8-w10 w12 w14 w15 w18-w20 w22 Random community sample (4)w7 w13 w21 w23 H pylori assessment Serology (7)w1-w3 w6 w7 w22 w23 Urea breath test (1)w9 Endoscopically obtained biopsy (15)w4 w5 w8 w10-w21 Definition of non-ulcer dyspepsia Duration more than 4 weeks (12)w1 w2 w4-w6 w8-w11 w13-w15 w18-w22 No organic disease found on investigation (16)w1 w4-w6 w8-w11 w13-w15 w18-w22 Upper abdominal or epigastric pain or discomfort (16)w1 w2 w4-w7 w11-w18 w21 w22 Symptoms related to meals (9)w1 w4-w6 w11 w12 w14 w15 w18 Other symptoms such as heartburn, nausea, or vomiting (12)w2 w5-w7 w12-w15 w17 w18 w21 w23 Not defined (5)w3 w8 w10 w19 w20 Exclusion criteria History of: Concomitant non-steroidal anti-inflammatory drugs (8)w2 w5 w6 w9 w12 w17 w18 w20 Previous eradication therapy for H pylori (8)w2 w3 w5 w11 w12 w15 w16 w18 Concomitant acid suppression therapy (4)w2 w11 w15 w20 |
=0.84).19
Summary estimates
Figure 1 shows the odds ratios and summary odds ratio for
each association study. Twenty three studies were pooled giving a
summary odds ratio of 1.6 (95% confidence interval 1.4 to 1.8) for
H pylori infection related to non-ulcer dyspepsia (P<0.001). The test for homogeneity was statistically significant (P<0.001). The summary odds ratios and 95% confidence intervals for
symptoms of abdominal pain (three studies), abdominal distension, flatulence, bloating, or belching (four), and nausea and vomiting (three) were respectively 1.2 (0.96 to 1.4), 1.2 (0.67 to 21.0), and
0.8 (0.4 to1.4). All were statistically
non-significant.
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Sensitivity analysis
The table shows the influence of study design, quality
scores, and control of confounders on pooled estimates. Summarised
estimates were statistically homogeneous for prevalence studies,
studies with quality scores above the median, and studies that
controlled for confounding.
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Eradication trials
Study characteristics and quality assessment scores
Five eradication trials provided data on change in
dyspeptic symptoms in patients in whom H pylori had or had not been eradicated (see website).w24-w28 This
change was defined as an improvement, or no
change or worsening of dyspeptic symptoms. The 18 other eradication
trials could not be included in a pooled analysis because they did not
provide data on change in symptoms in relation to H pylori
eradication.
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pain or discomfort in the
upper abdomen in association with other symptoms such as bloating,
nausea, or vomiting, relation with meals, worse at night, and reflux.
All eradication trials recruited patients from specialty or
gastroenterology clinics, and four trials assessed H pylori infection from endoscopically obtained biopsies. Three trials used
single regimen therapy, and two trials used triple regimen therapy. The
single therapy trials followed patients for less than 8 weeks whereas
the triple therapy trials assessed H pylori eradication and
change in dyspeptic symptoms at 12 months.
Out of a possible 100 the mean (SD) quality score for the five
eradication trials was 48.4 (16.1), median 42. Most studies lost points
for no description of randomisation or blinding, no assessment of
treatment compliance, and poor presentation of results. There was good
agreement between the two quality assessors (
=0.7).19
Summary estimates
We compared the change in dyspeptic symptoms in patients
with non-ulcer dyspepsia in whom H pylori had or had not
been eradicated. Figure 2 shows the odds ratios and summary odds ratio
for each eradication trial. The odds ratio for symptomatic improvement
was 1.9 (1.3 to 2.6) for patients in whom H pylori was
eradicated (P=0.001). This estimate was statistically homogeneous (P=0.046).
Sensitivity analysis
The table shows the influence of H pylori therapeutic regimen and study quality on the summary estimates. The
summary odds ratio for single therapy regimens was higher than for
triple therapy regimens. Quality scores for the two trials examining
triple therapy regimens were above the median as opposed to the three
trials examining single therapy regimens.
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Discussion |
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The association studies included in our meta-analysis showed a small yet statistically significant increased risk of non-ulcer dyspepsia in people infected with H pylori. Patients with non-ulcer dyspepsia in whom H pylori was eradicated were almost twice as likely to show an improvement in their dyspeptic symptoms than patients in whom H pylori was not eradicated.
Association studies
The overall summary estimate for the association studies
was fairly robust with respect to quality score, the control of
confounders, and study design. Interestingly, a higher summary odds
ratio was produced from the case-control studies than from the
prevalence studies. This may reflect differences in the severity or
frequency of dyspeptic symptoms. The prevalence studies utilised structured questionnaires in the general populations to identify subjects with non-ulcer dyspepsia whereas the case-control studies identified such subjects from patients seeking medical treatment. The
risk of H pylori infection increases with advancing age,
lower occupational status, and lower socioeconomic
status,25 and controlling for these factors should reduce
the heterogeneity of summary estimates. Statistical heterogeneity was
reduced among association studies that controlled for confounding and
also among studies with quality scores above the median. The design of
the association study did not explain statistical heterogeneity.
Eradication regimens
Triple regimen therapies are the currently accepted
treatment for H pylori eradication.26 Although
the number of trials in the sensitivity analysis was small, pooling the
triple regimens produced a lower summary odds ratio than the single
therapy regimens (see table). Although H pylori eradication was achieved at the time improvements in dyspeptic symptoms were assessed the magnitude of this improvement may have been affected by
the regimens used. Colloidal bismuth salicylate is known to improve
symptoms irrespective of H pylori infection, as does
omeprazole.
27 28
The triple regimens were also used in
trials with higher quality scores and longer follow up intervals.
Perceived improvements in dyspeptic symptoms may decrease over time and
this may explain the lower estimate in the triple than single regimen
trials. Therefore, the type of regimen used, the duration of follow up,
and the quality of the trial limits the generalisability of this
estimate. Further trials that use currently acceptable eradication
regimens and that monitor dyspeptic symptoms over longer time intervals
are required.
Definitions
Dyspepsia
Inconsistent definitions of dyspepsia may contribute
to the conflicting evidence provided by trials of H pylori
eradication. The definition of dyspepsia has been refined over the
years to represent pain or discomfort centred in the upper abdomen
described as bloating, distension, fullness, or nausea but not acid
regurgitation or heartburn.29 These symptoms should be
present for at least a month. Dyspeptic symptoms have generally been
poor in discriminating functional from organic disease.
30 31
Non-ulcer dyspepsia refers to the presence
of dyspeptic symptoms in the absence of an identifiable organic
disease.32 Depending on the symptoms used to define
dyspeptic patients the benefits of treatments may be either augmented
or diminished.33
Symptoms and scores
Similarly, different symptoms and scores have been used to
assess treatment response in trials of H pylori eradication. Although virtually all scores include upper abdominal pain or discomfort there are a variety of other symptoms included. Likert scales are subject to different interpretations by respondents, leading
to misclassification bias.34 In addition to this the weights of scales used in the trials of H pylori eradication
ranged from three to seven levels. Validated dyspeptic symptom scores would enable comparisons between different treatment modalities assessed in trials, including trials of H pylori eradication.
Limitations
Meta-analyses have their limitations.35-37 Publication bias tends to lead to the inclusion of studies that only
show a positive result. There are limitations to Medline searches as
our search failed to identify 16 articles, which were found only when
searching the references of papers. A potential for a selection bias
exists since the studies included in our meta-analysis did
not include information published in textbooks, non-English
language articles, and abstract only publications.
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What is already known on this topic
Although infection with Helicobacter pylori is strongly associated with peptic ulcer disease the relation with non-ulcer dyspepsia is controversial The adoption of empirical eradication regimens for non-ulcer dyspepsia is difficult given the little information about their efficacy Recently published randomised controlled trials allow an estimation of the change in dyspeptic symptoms among patients What this paper addsThis meta-analysis found a small yet statistically significant relation between H pylori infection and non-ulcer dyspepsia Eradication of H pylori was associated with an almost twofold improvement in dyspeptic symptoms among patients referred to specialty clinics This quantitative estimate may be used in primary care trials to determine the effectiveness and cost effectiveness of empirical eradication of H pylori in non-ulcer dyspepsia |
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Conclusions |
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A quantitative estimate gives a sense of the
magnitude of the relation between a risk factor and a disease. We found
that people infected with H pylori are about one and a half
to twice as likely to have non-ulcer dyspepsia compared with controls. Eradicating H pylori results in almost a twofold improvement
in dyspeptic symptoms. It is not yet known whether the magnitude of
these estimates is large enough to influence clinical guidelines or
clinicians, but the summary effect size estimates from our meta-analysis could help with sample size calculations for future studies. Such studies should include primary care patient populations where the efficacy of empirical therapy for dyspeptic patients with
H pylori infection may be examined.
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Acknowledgments |
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Contributors: RLJ had the original idea for the study, retrieved articles, extracted data, performed assessments of study quality, and undertook the statistical analysis; she will act as guarantor for the paper. EB extracted data, performed quality assessments, and assisted with the statistical analysis. FT assisted with the interpretation and presentation of the results. RLJ, EB, and FT jointly wrote the paper.
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Footnotes |
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Funding: The Adam Linton fellowship is sponsored by the Ontario Medical Association.
Competing interests: None declared.
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(Accepted 11 August 1999)
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