food ingestion. The reduction duration of POI afforded by chewing
gum is supported by several studies.12–25 However, other studies
have obtained null results.26–32 These discrepant evidences leave
uncertainty in the surgical field about the efficacy of chewing gum
in reducing the duration of POI. Several meta-analyses33–37 showed
a favorable effect of gum chewing on time to flatus and defecation,
but all of these studies were small number size(less than 9 trials)
and the results were not robust. Accordingly, we performed a
systematic meta-analysis of randomized controlled trials (RCTs)
to critically evaluate whether chewing gum reduces the duration of
POI after abdominal surgery. If any, this may bring in providing
an inexpensive, well-tolerated, and widely available solution to
ameliorate an old problem.
Methods
We attempted to follow the proposals Quality of Reports of
Meta-Analyses of Randomized Controlled Trials: the QUOROM
statement to report our meta-analysis.38
Search strategy. Electronic databases MEDLINE,
EMBASE, and Cochrane Library were used to search for RCTs up
to December 2012. The final search strategy used for each database
was based on key words both alone and combinations of the
terms “chewing gum” and “surgery.” A manual search of the reference
lists of relevant articles was performed.Asystematic search
of Google Scholar was used to explore the gray literature. No
language or time restrictions were made. Two reviewers (Yanqiong
Liu and Li Shan) independently evaluated all retrieved articles
using prespecified eligibility criteria. Disagreements were
resolved by consensus. When a study reported the results on different
indication of surgery, we treated it as separate studies in the
meta-analysis.
Eligibility criteria. Studies were considered eligible if they
met the following inclusion criteria: (i) Study design: randomized
and controlled; (ii) Population: patients undergoing abdominal
surgery; (iii) Intervention: use of chewing gum in the
postoperative period; (iv) Comparator: standard postoperative
care; (v) Outcome: report at least one of time to flatus, time to
bowel movement, and hospital LOS. We did not use an age criterion
and any minimum number of patients for inclusion in this
meta-analysis.
Studies were excluded if any of the following existed: (i) nonrandomized
study design; (ii) surgeries that did not involve
abdominal surgery; (iii) primary outcome was not the interest of
ours; (iv) interventions other than chewing gum; (vi) raw data
could not be extracted in the appropriate format and failed to be
obtained from the authors or other published results.