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A Messori a Laboratorio SIFO di Farmacoeconomia,
Centro Informazione Farmaci, Servizio Farmaceutico, Azienda Ospedaliera
Careggi, 50134 Florence, Italy, b Unita' di Terapia Intensiva
Respiratoria, Azienda Ospedaliera Careggi
Correspondence to: A Messori md3439{at}mclink.it
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Abstract |
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Objectives:
To determine the effectiveness of
ranitidine and sucralfate in the prevention of stress ulcer in critical
patients and to assess if these treatments affect the risk of
nosocomial pneumonia.
Ranitidine and sucralfate are widely used to prevent stress ulcers
in patients admitted to intensive care units.1 A
meta-analysis published by Cook et al in 1996 showed that
H2 receptor antagonists (such as cimetidine and
ranitidine together) are more effective than placebo for this clinical
indication.2 With regard to sucralfate, this meta-analysis
found a small but significant reduction in overt bleeding but no effect
on clinically important events. The meta-analysis did not resolve the
question of an increased risk of nosocomial pneumonia related to the
use of H2 receptor antagonists.
Several arguments emphasise the need for up to date information on this
issue. Firstly, ranitidine has become the main H2 receptor antagonist used for prophylaxis for stress ulcers, and cimetidine has generally been abandoned1; secondly, new
findings have been published on effectiveness and complications of
ranitidine; and, thirdly, a meta-analytic comparison of ranitidine
versus placebo has never been carried out, and as the comparison of
sucralfate and placebo made by Cook et al gave no proof of the
effectiveness of this drug, ranitidine and sucralfate might both be
ineffective. Another problem is that the most recent randomised studies
on this topic did not include a group with no prophylaxis and compared supposedly active treatments with one another.
3 4
We conducted a literature search to identify randomised trials, and we
carried out a meta-analysis to update the results of Cook's study with
regard to effectiveness and infectious complications.
Searching
Design:
Published studies retrieved through
Medline and other databases. Five meta-analyses evaluated effectiveness in terms of bleeding rates (A: ranitidine v placebo; B:
sucralfate v placebo) and infectious complications in terms
of incidence of nosocomial pneumonia (C: ranitidine v
placebo; D: sucralfate v placebo; E: ranitidine
v sucralfate). Trial quality was determined with an
empirical ad hoc procedure.
Main outcome measures:
Rates of clinically important
gastrointestinal bleeding and nosocomial pneumonia (compared between
the two study arms and expressed with odds ratios specific for
individual studies and meta-analytic summary odds ratios).
Results:
Meta-analysis A (five studies) comprised 398 patients; meta-analysis C (three studies) comprised 311 patients; meta-analysis D (two studies) comprised 226 patients: and meta-analysis E (eight studies) comprised 1825 patients. Meta-analysis B was not
carried out as the literature search selected only one clinical trial.
In meta-analysis A ranitidine was found to have the same effectiveness
as placebo (odds ratio of bleeding 0.72, 95% confidence interval 0.30 to 1.70, P=0.46). In placebo controlled studies (meta-analyses C and D)
ranitidine and sucralfate had no influence on the incidence of
nosocomial pneumonia. In comparison with sucralfate, ranitidine
significantly increased the incidence of nosocomial pneumonia
(meta-analysis E: 1.35, 1.07 to 1.70, P=0.012). The mean quality score
in the four analyses (on a 0 to 10 scale) ranged from 5.6 in
meta-analysis E to 6.6 in meta-analysis A.
Conclusions:
Ranitidine is ineffective in the
prevention of gastrointestinal bleeding in patients in intensive care
and might increase the risk of pneumonia. Studies on sucralfate do not
provide conclusive results. These findings are based on small numbers
of patients, and firm conclusions cannot presently be proposed.
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Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
Appendix
References
![]()
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
Appendix
References
Our Medline search covered the period from 1966 to 20 June 2000 and was based on four key words (stress, pneumonia, ranitidine,
sucralfate) and on the extraction of studies published in English (see
Appendix ). Randomised studies were identified by using the key words
"randomized controlled trial" or "random" according to a
validated literature search.5
Selection
On the basis of the material produced by our search, we carried
out five meta-analyses that evaluated data on effectiveness in terms of
rates of bleeding (meta-analysis A: ranitidine v placebo;
meta-analysis B: sucralfate v placebo) and data of
infectious complications in terms of incidence of nosocomial pneumonia
(meta-analysis C: ranitidine v placebo; meta-analysis D:
sucralfate v placebo; meta-analysis E: ranitidine
v sucralfate). We investigated the issue of effectiveness
only in studies with a control group that received no prophylaxis,
while the issue of infectious complications was also assessed from
comparative trials of ranitidine versus sucralfate. Eligible studies
were included in meta-analysis A or B if they met the following
criteria: patients were admitted to an intensive care unit or were
undergoing mechanical ventilation, or both; randomised design;
assessment of gastrointestinal bleeding. We excluded studies in which
gastrointestinal bleeding did not meet the definition of "clinically
important bleeding" according to Cook et al.2 In
meta-analyses C, D, and E the inclusion criterion gastrointestinal
bleeding was replaced by the assessment of pneumonia. The definitions
of pneumonia adopted by the individual investigators were recorded but
were not assumed to be an inclusion or exclusion criterion.
Data extraction
Data were extracted by one reviewer (MV) with a structured form
and checked for accuracy by a second
reviewer (ST). Differences were resolved by consensus.
Assessment of quality of trials
We assessed methodological quality of the trials using a procedure
similar to that adopted by Cook et al.2 Five items were
evaluated for each trial (patient selection, patient characteristics,
randomisation, blinding, definition of bleeding or of pneumonia).
Methodological quality was graded for each of the five items on a scale
of 0, 1, or 2 (maximum score=10). Three observers
independently assessed quality (AM, MV,
MG). Differences were resolved
by consensus.
Qualitative data synthesis
Descriptive data for each trial included characteristics of
participants, details of intervention, and definition of outcomes. Our
assessment of clinical heterogeneity was focused in particular on a
comparison of the definitions of bleeding and pneumonia across the trials.
Quantitative data synthesis
With regard to the two end points, the odds ratio was used as the
principal measure for comparing the treatment effect within each trial.
The results specific for trials were combined through standard
meta-analytic techniques6-8 to produce the summary odds
ratio together with an assessment of the statistical intertrial
heterogeneity. The meta-analysis calculations were based both on a
fixed effect model
6 7
and on a
random effect model.
6 8
The 95% confidence
intervals for the odds ratio of individual studies were computed
according to Wolf 9 (or by the "rule of
three"10 when zeros were present). To avoid the problems
of bias and instability associated with estimation of odds ratios, 0.5 was added to each cell of the fourfold tables in keeping with Cook et
al.2 Heterogeneity was assessed as previously
described.7
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Results |
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Table 1 shows the trial flow for the five meta-analyses. There were 398 patients in meta-analysis A (five studies), 54 in meta-analysis B (one study), 311 in meta-analysis C (three studies), 226 in meta-analysis D (two studies), and 1825 in meta-analysis E (eight studies). Table 2 shows descriptive data for all the trials included in our meta-analyses.
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Effectiveness of ranitidine v placebo (meta-analysis
A)
Our literature search identified five
trials,11-15 three of which had already been included by
Cook et al.11-13 The mean (SD) quality score for these
trials was 6.6 (0.9). With respect to the end point of clinically
important bleeding, this meta-analysis (table 3) failed to show any
significant benefit of ranitidine (summary odds ratio 0.72, 95%
confidence interval 0.30 to 1.70, P=0.46 for fixed effect model; 0.95, 0.37 to 2.43, P=0.92 for random effect model;
2 for
heterogeneity 6.8, df 4, P=0.15).
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Effectiveness of sucralfate v placebo (meta-analysis B)
Our
literature search found the same randomised trials that had already been examined by Cook et al (three trials16-18 for the end
point of overt bleeding and one trial11 for the end point
of clinically important gastrointestinal bleeding). Because our
analysis considered the end point of clinically important bleeding,
only one trial11 met the inclusion criteria and so no
meta-analysis was carried out. The quality score of the trial of
Ruiz-Santana et al was 7.0. The results of the study by Cook et al
remained unchanged (table 4) with no difference between sucralfate and
placebo (1.26, 0.12 to 12.9, P=0.70).
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Incidence of pneumonia with ranitidine v placebo (meta-analysis
C)
Our third meta-analysis included three randomised
studies
12 13 15
that compared the incidence of pneumonia
between ranitidine and placebo (two of these
trials
12 13
had already been included in the
meta-analysis by Cook et al). The mean (SD) quality score for these
trials was 6.0 (1.0). The analysis of these three trials (table 5)
found no significant difference in the rate of pneumonia with
ranitidine and placebo (summary odds ratio 0.98, 0.56 to 1.72, P=0.94
for fixed effect model; 1.10, 0.45 to 2.66, P=0.84 for random effect model;
2 for heterogeneity 4.38, df 2, P=0.11).
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Incidence of pneumonia with sucralfate v placebo (meta-analysis
D)
Our fourth meta-analysis included two randomised
studies
17 18
that compared the incidence of
pneumonia between sucralfate and placebo (both trials had already been
included in the meta-analysis by Cook et al). The quality score for
these trials was 6.0 (1.4). The analysis of these two trials (table 6)
found no significant difference in the rate of pneumonia with
sucralfate and placebo (summary odds ratio 2.21, 0.86 to 5.65, P=0.10
for fixed effect model; 2.11, 0.79 to 5.64, P=0.14 for random effect
model;
2 for heterogeneity 0.30, df 1, P=0.58).
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Incidence of pneumonia with ranitidine v sucralfate
(meta-analysis E)
Our fifth meta-analysis included eight
randomised studies
3 19-26
that compared the incidence of
pneumonia with ranitidine and sucralfate (five of
these trials19-23 had already been included in the
meta-analysis by Cook et al). The quality score for these trials was
5.6 (2.3). The analysis of these eight trials (table 7) showed a
significantly increased risk of pneumonia with ranitidine compared with
sucralfate (summary odds ratio 1.35, 1.07 to 1.70, P=0.012 for fixed
effect model; 1.51, 1.00 to 2.29, P=0.05 for random effect model;
2 for heterogeneity 12.9, df 7, P=0.08).
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Discussion |
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Our overview of the controlled trials of ranitidine or sucralfate compared with placebo provides a picture of poor effectiveness. The single trial available on sucralfate11 does not allow any conclusion to be drawn; the trials on ranitidine11-15 show no difference compared with placebo.
Our results on ranitidine need to be compared with those previously published by Cook et al.2 In their assessment of effectiveness of H2 receptor antagonists Cook et al included five trials that used cimetidine29-33 and three trials with negative results that used ranitidine11-13 (plus one trial on ranitidine published in Spanish34 and one trial with negative results that used a combination of ranitidine and antacids,35 both of which did not meet the criteria for our meta-analysis). Cimetidine is probably effective at statistical levels, as out of the trials that used cimetidine three had positive results, one had significant results in patients at low risk, and one had negative results. A separate meta-analysis that we carried out for this purpose (table 8) showed a significant reduction in bleeding (with P<0.001 and P<0.01 according to the fixed effect and the random effect models, respectively).
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Can we accept the hypothesis that cimetidine is effective and ranitidine is ineffective? Is this hypothesis pharmacologically plausible? Our separate analyses for individual drugs did not actually settle the entire question. In fact, the cohorts included in the studies that used these two drugs were small and the incidence of events was low, particularly in the case of ranitidine (10 cases of bleeding with the drug v 15 without prophylaxis; table 3); so the different results might reflect casual variations in the outcome rather than a true difference between the two H2 receptor antagonists. Another point of uncertainty about cimetidine is the methodological quality of studies published many years ago.
Design of new trials
Our results indicate that some points of consensus need to be
revised. For example, recent randomised studies on prophylaxis for
stress ulcers
3 4
have invariably compared (unproved)
active treatments with one another but no longer use a placebo group,
and authoritative recommendations suggest the use of ranitidine for
prophylaxis for stress ulcers.36
Effect on pneumonia
The results of three meta-analyses that evaluated pneumonia were
contradictory in some respects (ranitidine v placebo and sucralfate
v placebo had the same incidence of pneumonia; for
ranitidine v sucralfate there was a significantly higher
incidence of pneumonia with ranitidine, P=0.012).The statistical power
of these comparisons was better for meta-analysis E (1825 patients) than for meta-analysis C (311 patients); this could in part explain the
higher incidence of pneumonia with ranitidine compared with sucralfate
but not compared with placebo.
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What is already known on this topic
Ranitidine and sucralfate are widely used to prevent gastrointestinal bleeding in patients in intensive care Several recommendations suggest this form of prophylaxis, but both the Food and Drug Administration and European Medicines Evaluation Agency have not given their approval What this study addsThis analysis showed that ranitidine and sucralfate do not prevent gastrointestinal bleeding in patients in intensive care Ranitidine can increase the risk of nosocomial pneumonia under certain circumstances These findings are based on small numbers of patients and so firm conclusions cannot presently be proposed Current recommendations on prophylaxis for stress ulcers should be revised according to these results |
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Acknowledgments |
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We thank Dr Enrico Tendi, head of the pharmaceutical service of the Careggi hospital, for stimulating the discussion on this topic.
Contributors: AM had the original idea for the present study, set up the project, designed the protocol, organised searches, supervised data extraction, supervised cross checking and validation work, assessed methodological quality of the trials, carried out statistical calculations, and discussed analysis and subsequent results. ST had the original idea for the present study, set up the project, designed the protocol, organised searches, checked accuracy of data extraction, supervised cross checking and validation work, carried out statistical calculations, and discussed analysis and subsequent results. MV was involved in the original project, helped to devise protocol, organised searches, extracted data from the studies, assessed methodological quality of the trials, arranged statistical input, collaborated in analyses, and discussed analysis and subsequent results. MG was involved in the original project, helped to devise protocol and organise searches, assessed methodological quality of the trials, collaborated in analyses, and discussed analysis and subsequent results. AC was involved in the original project, helped to devise protocol and organise searches, supervised data extraction, collaborated in analyses, and discussed analysis and subsequent results. The paper was written jointly by AM and ST. AM is guarantor.
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Footnotes |
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Funding: None.
Competing interests: On other occasions, our group has received support from GlaxoWellcome (Italy) in the following terms: AM has received funds for a member of his staff (MV) working on a pharmacoeconomic project on colon cancer; ST has been reimbursed for attending three symposiums; MV received financial support for the colon cancer project and a fee for consulting about remifentanil; AC has received a fee for speaking and a fee for organising an educational seminar.
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Appendix |
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Literature search
Our literature search used the PubMed version of Medline on the internet (www.ncbi.nlm.nih.gov/entrez/). The syntax used for the Medline searches of our five meta-analyses was:
Meta-analysis A: ranitidine AND stress AND eng [LA] AND 1966:2000 [EDAT] AND (Randomized Controlled Trial [PT] OR random* [TW])
Meta-analysis B: sucralfate AND stress AND eng [LA] AND 1966:2000 [EDAT] AND (Randomized Controlled Trial [PT] OR random* [TW])
Meta-analysis C: ranitidine AND pneumonia AND eng [LA] AND 1966:2000 [EDAT] AND Randomized Controlled Trial [PT] OR random* [TW])
Meta-analysis D: sucralfate AND pneumonia AND eng [LA] AND 1966:2000 [EDAT] AND (Randomized Controlled Trial [PT] OR random* [TW])
Meta-analysis E: ranitidine AND sucralfate AND pneumonia AND eng [LA] AND 1966:2000 [EDAT] AND (Randomized Controlled Trial [PT] OR random* [TW])
In this syntax, "eng[LA]" identifies studies published in English language, "1966:2000[EDAT]" selects the year range according to the Entrez date, "Randomized Controlled Trial [PT]" selects this type of trials according to Medical Subjects Headings while "random*"[TW] indicates the word random (in its all variant endings) in the title or abstract; the last two conditions were stated with the "OR" Boolean operator to increase the power of the search.
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References |
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(Accepted 1 August 2000)
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