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Chewing gum for postoperative recovery of gastrointestinal
function (Review)
Short V, Herbert G, Perry R, Atkinson C, Ness AR, Penfold C, Thomas S, Andersen HK, Lewis SJ
Short V, Herbert G, Perry R, Atkinson C, Ness AR, Penfold C, Thomas S, Andersen HK, Lewis SJ.
Chewing gum for postoperative recovery of gastrointestinal function.
Cochrane Database of Systematic Reviews 2015, Issue 2. Art. No.: CD006506.
DOI: 10.1002/14651858.CD006506.pub3.
www.cochranelibrary.com
Chewing gum for postoperative recovery of gastrointestinal function (Review)
Copyright © 2015 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
, Cochrane Trusted evidence.
Informed decisions.
Library Better health. Cochrane Database of Systematic Reviews
TABLE OF CONTENTS
HEADER......................................................................................................................................................................................................... 1
ABSTRACT..................................................................................................................................................................................................... 1
PLAIN LANGUAGE SUMMARY....................................................................................................................................................................... 2
SUMMARY OF FINDINGS.............................................................................................................................................................................. 3
BACKGROUND.............................................................................................................................................................................................. 6
OBJECTIVES.................................................................................................................................................................................................. 6
METHODS..................................................................................................................................................................................................... 7
Figure 1.................................................................................................................................................................................................. 8
RESULTS........................................................................................................................................................................................................ 10
Figure 2.................................................................................................................................................................................................. 12
Figure 3.................................................................................................................................................................................................. 15
Figure 4.................................................................................................................................................................................................. 18
Figure 5.................................................................................................................................................................................................. 19
Figure 6.................................................................................................................................................................................................. 21
Figure 7.................................................................................................................................................................................................. 22
Figure 8.................................................................................................................................................................................................. 23
Figure 9.................................................................................................................................................................................................. 24
Figure 10................................................................................................................................................................................................ 25
Figure 11................................................................................................................................................................................................ 26
DISCUSSION.................................................................................................................................................................................................. 28
AUTHORS' CONCLUSIONS........................................................................................................................................................................... 30
ACKNOWLEDGEMENTS................................................................................................................................................................................ 31
REFERENCES................................................................................................................................................................................................ 32
CHARACTERISTICS OF STUDIES.................................................................................................................................................................. 40
DATA AND ANALYSES.................................................................................................................................................................................... 162
Analysis 1.1. Comparison 1 Control, Outcome 1 Time to first flatus................................................................................................. 165
Analysis 1.2. Comparison 1 Control, Outcome 2 Time to first bowel movement.............................................................................. 167
Analysis 1.3. Comparison 1 Control, Outcome 3 Length of hospital stay.......................................................................................... 168
Analysis 1.4. Comparison 1 Control, Outcome 4 Time to first bowel sounds................................................................................... 170
Analysis 1.5. Comparison 1 Control, Outcome 5 Complications - Nausea and Vomiting [Frequency]............................................. 171
Analysis 1.6. Comparison 1 Control, Outcome 6 Complications - Mortality [Frequency]................................................................. 171
Analysis 1.7. Comparison 1 Control, Outcome 7 Complications - Infection [Frequency]................................................................. 172
Analysis 1.8. Comparison 1 Control, Outcome 8 Complications - Readmissions [Frequency]......................................................... 172
Analysis 1.9. Comparison 1 Control, Outcome 9 Complications - Other [Frequency]...................................................................... 173
Analysis 1.10. Comparison 1 Control, Outcome 10 Complications related to the intervention [Frequency]................................... 174
Analysis 1.11. Comparison 1 Control, Outcome 11 Tolerability of gum............................................................................................ 174
Analysis 1.12. Comparison 1 Control, Outcome 12 Cost.................................................................................................................... 176
ADDITIONAL TABLES.................................................................................................................................................................................... 176
APPENDICES................................................................................................................................................................................................. 179
WHAT'S NEW................................................................................................................................................................................................. 196
HISTORY........................................................................................................................................................................................................ 196
CONTRIBUTIONS OF AUTHORS................................................................................................................................................................... 197
DECLARATIONS OF INTEREST..................................................................................................................................................................... 197
SOURCES OF SUPPORT............................................................................................................................................................................... 197
DIFFERENCES BETWEEN PROTOCOL AND REVIEW.................................................................................................................................... 198
NOTES........................................................................................................................................................................................................... 198
INDEX TERMS............................................................................................................................................................................................... 198
Chewing gum for postoperative recovery of gastrointestinal function (Review) i
Copyright © 2015 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
, Cochrane Trusted evidence.
Informed decisions.
Library Better health. Cochrane Database of Systematic Reviews
[Intervention Review]
Chewing gum for postoperative recovery of gastrointestinal function
Vaneesha Short1, Georgia Herbert1, Rachel Perry1, Charlotte Atkinson1, Andrew R Ness1, Christopher Penfold1, Steven Thomas2,
Henning Keinke Andersen3, Stephen J Lewis4
1NIHR Biomedical Research Unit in Nutrition, Diet and Lifestyle, University Hospitals Bristol Education Centre, Bristol, UK. 2Head & Neck
Surgery, University Hospitals Bristol NHS Trust, Bristol, UK. 3The Cochrane Colorectal Cancer Group, Bispebjerg Hospital, Building 39N,
Copenhagen, Denmark. 4Dept of Gastroenterology, Level 7, Derriford Hospital, Plymouth, UK
Contact address: Vaneesha Short, NIHR Biomedical Research Unit in Nutrition, Diet and Lifestyle, University Hospitals Bristol Education
Centre, Upper Maudlin Street, Bristol, Avon, BS2 8AE, UK. vaneesha.short@bristol.ac.uk.
Editorial group: Cochrane Colorectal Cancer Group.
Publication status and date: Edited (no change to conclusions), published in Issue 5, 2015.
Citation: Short V, Herbert G, Perry R, Atkinson C, Ness AR, Penfold C, Thomas S, Andersen HK, Lewis SJ. Chewing gum for
postoperative recovery of gastrointestinal function. Cochrane Database of Systematic Reviews 2015, Issue 2. Art. No.: CD006506. DOI:
10.1002/14651858.CD006506.pub3.
Copyright © 2015 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
ABSTRACT
Background
Ileus commonly occurs after abdominal surgery, and is associated with complications and increased length of hospital stay (LOHS). Onset
of ileus is considered to be multifactorial, and a variety of preventative methods have been investigated. Chewing gum (CG) is hypothesised
to reduce postoperative ileus by stimulating early recovery of gastrointestinal (GI) function, through cephalo-vagal stimulation. There is
no comprehensive review of this intervention in abdominal surgery.
Objectives
To examine whether chewing gum after surgery hastens the return of gastrointestinal function.
Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (via Ovid), MEDLINE (via PubMed), EMBASE (via Ovid),
CINAHL (via EBSCO) and ISI Web of Science (June 2014). We hand-searched reference lists of identified studies and previous reviews and
systematic reviews, and contacted CG companies to ask for information on any studies using their products. We identified proposed and
ongoing studies from clinicaltrials.gov, World Health Organization (WHO) International Clinical Trials Registry Platform and metaRegister
of Controlled Trials.
Selection criteria
We included completed randomised controlled trials (RCTs) that used postoperative CG as an intervention compared to a control group.
Data collection and analysis
Two authors independently collected data and assessed study quality using an adapted Cochrane risk of bias (ROB) tool, and resolved
disagreements by discussion. We assessed overall quality of evidence for each outcome using Grades of Recommendation, Assessment,
Development and Evaluation (GRADE). Studies were split into subgroups: colorectal surgery (CRS), caesarean section (CS) and other
surgery (OS). We assessed the effect of CG on time to first flatus (TFF), time to bowel movement (TBM), LOHS and time to bowel sounds
(TBS) through meta-analyses using a random-effects model. We investigated the influence of study quality, reviewers’ methodological
estimations and use of Enhanced Recovery After Surgery (ERAS) programmes using sensitivity analyses. We used meta-regression to
explore if surgical site or ROB scores predicted the extent of the effect estimate of the intervention on continuous outcomes. We reported
frequency of complications, and descriptions of tolerability of gum and cost.
Chewing gum for postoperative recovery of gastrointestinal function (Review) 1
Copyright © 2015 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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Informed decisions.
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Main results
We identified 81 studies that comprised 9072 participants for inclusion in our review. We categorised many studies at high or unclear risk of
the bias' assessed. There was statistical evidence that use of CG reduced TFF [overall reduction of 10.4 hours (95% CI: -11.9, -8.9): 12.5 hours
(95% CI: -17.2, -7.8) in CRS, 7.9 hours (95% CI: –10.0, -5.8) in CS, 10.6 hours (95% CI: -12.7, -8.5) in OS]. There was also statistical evidence
that use of CG reduced TBM [overall reduction of 12.7 hours (95% CI: -14.5, -10.9): 18.1 hours (95% CI: -25.3, -10.9) in CRS, 9.1 hours (95%
CI: -11.4, -6.7) in CS, 12.3 hours (95% CI: -14.9, -9.7) in OS]. There was statistical evidence that use of CG slightly reduced LOHS [overall
reduction of 0.7 days (95% CI: -0.8, -0.5): 1.0 days in CRS (95% CI: -1.6, -0.4), 0.2 days (95% CI: -0.3, -0.1) in CS, 0.8 days (95% CI: -1.1, -0.5) in
OS]. There was statistical evidence that use of CG slightly reduced TBS [overall reduction of 5.0 hours (95% CI: -6.4, -3.7): 3.21 hours (95%
CI: -7.0, 0.6) in CRS, 4.4 hours (95% CI: -5.9, -2.8) in CS, 6.3 hours (95% CI: -8.7, -3.8) in OS]. Effect sizes were largest in CRS and smallest in
CS. There was statistical evidence of heterogeneity in all analyses other than TBS in CRS.
There was little difference in mortality, infection risk and readmission rate between the groups. Some studies reported reduced nausea and
vomiting and other complications in the intervention group. CG was generally well-tolerated by participants. There was little difference in
cost between the groups in the two studies reporting this outcome.
Sensitivity analyses by quality of studies and robustness of review estimates revealed no clinically important differences in effect estimates.
Sensitivity analysis of ERAS studies showed a smaller effect size on TFF, larger effect size on TBM, and no difference between groups for
LOHS.
Meta-regression analyses indicated that surgical site is associated with the extent of the effect size on LOHS (all surgical subgroups), and
TFF and TBM (CS and CRS subgroups only). There was no evidence that ROB score predicted the extent of the effect size on any outcome.
Neither variable explained the identified heterogeneity between studies.
Authors' conclusions
This review identified some evidence for the benefit of postoperative CG in improving recovery of GI function. However, the research to
date has primarily focussed on CS and CRS, and largely consisted of small, poor quality trials. Many components of the ERAS programme
also target ileus, therefore the benefit of CG alongside ERAS may be reduced, as we observed in this review. Therefore larger, better quality
RCTS in an ERAS setting in wider surgical disciplines would be needed to improve the evidence base for use of CG after surgery.
PLAIN LANGUAGE SUMMARY
Chewing gum after surgery to help recovery of the digestive system
Background
When people have surgery on their abdomen, the digestive system can stop working for a few days. This is called ileus, and can be painful
and uncomfortable. There are different causes of ileus, and several ways of treating or preventing it. One possible way of preventing ileus is
by chewing gum. The idea is that chewing gum tricks the body into thinking it is eating, causing the digestive system to start working again.
It is important to do this review because ileus is common: it is estimated that up to a third of people having bowel surgery suffer from ileus.
Main Findings
This review found 81 relevant studies that recruited over 9000 participants in total. The studies mainly focussed on people having bowel
surgery or caesarean section, but there were some studies of other surgery types. There were few studies of children. Most studies were
of poor quality, which may mean their results are less reliable. We found some evidence that people who chewed gum after an operation
were able to pass wind and have bowel movements sooner than people who did not chew gum. We also found some evidence that people
who chewed gum after an operation had bowel sounds (gurgling sounds heard using a stethoscope held to the abdomen) slightly sooner
than people who did not chew gum. There was a small difference in how long people stayed in hospital between people who did or did not
chew gum. There were no differences in complications (such as infection or death) between people who did or did not chew gum. There
was also no difference in the overall cost of treatment between people who did or did not chew gum.
Conclusions
There is some evidence that chewing gum after surgery may help the digestive system to recover. However, the studies included in this
review are generally of poor quality, which meant that their results may not be reliable. We also know that there are many factors affecting
ileus, and that modern treatment plans attempt to reduce risk of ileus. Therefore to further explore using chewing gum after surgery, more
studies would be needed which are larger, of better quality, include different types of surgery, and consider recent changes in health care
systems.
Chewing gum for postoperative recovery of gastrointestinal function (Review) 2
Copyright © 2015 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.