Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting

122 Pages·2010·1.66 MB·English

Stimulation of the wrist acupuncture point P6 for preventing
postoperative nausea and vomiting (Review)
Lee A, Fan LTY
ThisisareprintofaCochranereview,preparedandmaintainedbyTheCochraneCollaborationandpublishedinTheCochraneLibrary
2009,Issue2
http://www.thecochranelibrary.com
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review)
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
TABLE OF CONTENTS
HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
PLAINLANGUAGESUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
SUMMARYOFFINDINGSFORTHEMAINCOMPARISON . . . . . . . . . . . . . . . . . . . 2
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
ADDITIONALSUMMARYOFFINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
AUTHORS’CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
CHARACTERISTICSOFSTUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
DATAANDANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Analysis1.1.Comparison1AcupointP6stimulationversussham,Outcome1Nausea. . . . . . . . . . . 86
Analysis1.2.Comparison1AcupointP6stimulationversussham,Outcome2Vomiting. . . . . . . . . . . 95
Analysis1.3.Comparison1AcupointP6stimulationversussham,Outcome3Rescueantiemetics. . . . . . . 105
Analysis2.1.Comparison2AcupointP6stimulationversusantiemeticdrug,Outcome1Nausea. . . . . . . . 107
Analysis2.2.Comparison2AcupointP6stimulationversusantiemeticdrug,Outcome2Vomiting. . . . . . . 111
Analysis2.3.Comparison2AcupointP6stimulationversusantiemeticdrug,Outcome3Rescueantiemetic. . . . 116
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
WHAT’SNEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
CONTRIBUTIONSOFAUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
DECLARATIONSOFINTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
SOURCESOFSUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
DIFFERENCESBETWEENPROTOCOLANDREVIEW . . . . . . . . . . . . . . . . . . . . . 120
NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
INDEXTERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) i
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
[InterventionReview]
Stimulation of the wrist acupuncture point P6 for preventing
postoperative nausea and vomiting
AnnaLee1,LawrenceTYFan1
1DepartmentofAnaesthesiaandIntensiveCare,TheChineseUniversityofHongKong,Shatin,HongKong
Contactaddress:AnnaLee,DepartmentofAnaesthesiaandIntensiveCare,TheChineseUniversityofHongKong,PrinceofWales
Hospital,Shatin,[email protected].
Editorialgroup:CochraneAnaesthesiaGroup.
Publicationstatusanddate:Newsearchforstudiesandcontentupdated(conclusionschanged),publishedinIssue2,2009.
Reviewcontentassessedasup-to-date: 18November2008.
Citation: LeeA,FanLTY.StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting.Cochrane
DatabaseofSystematicReviews2009,Issue2.Art.No.:CD003281.DOI:10.1002/14651858.CD003281.pub3.
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
ABSTRACT
Background
Postoperativenauseaandvomiting(PONV)arecommoncomplicationsfollowingsurgeryandanaesthesia.DrugstopreventPONV
areonlypartiallyeffective.AnalternativeapproachistostimulatetheP6acupointonthewrist.ThisisanupdateofaCochranereview
firstpublishedin2004.
Objectives
TodeterminetheefficacyandsafetyofP6acupointstimulationinpreventingPONV.
Searchstrategy
WesearchedCENTRAL(TheCochraneLibrary,Issue3,2008),MEDLINE(January1966toSeptember2008),EMBASE(January
1988toSeptember2008),ISIWebofScience(January1965toSeptember2008),theNationalLibraryofMedicinepublicationlist
ofacupuncturestudies,andreferencelistsofarticles.
Selectioncriteria
AllrandomizedtrialsoftechniquesthatstimulatedtheP6acupointcomparedwithshamtreatmentordrugtherapyfortheprevention
ofPONV.Interventionsusedinthesetrialsincludedacupuncture,electro-acupuncture,transcutaneousnervestimulation,laserstim-
ulation,capsicumplaster,anacu-stimulationdevice,andacupressureinpatientsundergoingsurgery.Primaryoutcomesweretherisks
ofnauseaandvomiting.Secondaryoutcomesweretheneedforrescueantiemetictherapyandadverseeffects.
Datacollectionandanalysis
Tworeviewauthorsindependentlyassessedtrialqualityandextractedthedata.Wecollectedadverseeffectinformationfromthetrials.
Weusedarandom-effectsmodelandreportedrelativerisk(RR)withassociated95%confidenceintervals(95%CI).
Mainresults
Weincluded40trialsinvolving4858participants;fourtrialsreportedadequateallocationconcealment.Twelvetrialsdidnotreport
alloutcomes.ComparedwithshamtreatmentP6acupointstimulationsignificantlyreduced:nausea(RR0.71,95%CI0.61to0.83);
vomiting(RR0.70,95%CI0.59to0.83),andtheneedforrescueantiemetics(RR0.69,95%CI0.57to0.83).Heterogeneityamong
trialswasmoderate.TherewasnocleardifferenceintheeffectivenessofP6acupointstimulationforadultsandchildren;orforinvasive
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 1
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
andnoninvasiveacupointstimulation.TherewasnoevidenceofdifferencebetweenP6acupointstimulationandantiemeticdrugsin
theriskofnausea(RR0.82,95%CI0.60to1.13),vomiting(RR1.01,95%CI0.77to1.31),ortheneedforrescueantiemetics(RR
0.82,95%CI0.59to1.13).ThesideeffectsassociatedwithP6acupointstimulationwereminor.Therewasnoevidenceofpublication
biasfromcontour-enhancedfunnelplots.
Authors’conclusions
P6acupointstimulationpreventedPONV.Therewasnoreliableevidencefordifferencesinrisksofpostoperativenauseaorvomiting
afterP6acupointstimulationcomparedtoantiemeticdrugs.
PLAIN LANGUAGE SUMMARY
P6acupointstimulationpreventspostoperativenauseaandvomitingwithfewsideeffects
Postoperativenauseaandvomiting(PONV)aretwoofthemostcommoncomplicationsafteranaesthesiaandsurgery.Drugsareonly
partiallyeffectiveinpreventingPONVandmaycauseadverseeffects.Alternativemethods,suchasstimulatinganacupuncturepoint
onthewrist(P6acupointstimulation),havebeenstudiedinmanytrials.TheuseofP6acupointstimulationcanreducetheriskof
nausea andvomiting aftersurgery,with minimal side effects.Therisks ofpostoperative nausea andvomiting weresimilar afterP6
acupointstimulationandantiemeticdrugs.
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 2
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
CopStim SUMMARY OF FINDINGS FOR THE MAIN COMPARISON [Explanation]
yrigula
ht©tion AcupointP6stimulationversusshamtopreventpostoperativenauseaandvomiting
2009ofthe Patientorpopulation:patientswithadesiretopreventpostoperativenauseaandvomiting
TheCwrist Settings:Surgery
oa Intervention:AcupointP6stimulationversussham
chcu
rp
au
nn
ec Outcomes Illustrativecomparativerisks*(95%CI) Relativeeffect NoofParticipants Qualityoftheevidence Comments
Ctu
ollaborrepoin (95%CI) (studies) (GRADE)
atiotP6 Assumedrisk Correspondingrisk
n.fo
Pr
ublishpreve Control AvecruspuosinsthaPm6 stimulation
en
dbtin
yg Nausea-Alltrials Lowriskpopulation1 RR0.71 2962 ⊕⊕⊕(cid:13)
JohnWpostop (0.61to0.83) (27) moderate2
iley&erativ 100per1000 71per1000
e (61to83)
Sons,Lnausea Highriskpopulation1
tda
.n
d
v
o 400per1000 284per1000
m
itin (244to332)
g
(R
ev Vomiting-Alltrials Lowriskpopulation1 RR0.7 3385 ⊕⊕⊕(cid:13)
ie
w (0.59to0.83) (32) moderate2
)
3
CS
optim
yrigula
httio 100per1000 70per1000
©n
2009ofthe (59to83)
TheCwrist Highriskpopulation1
oa
chrcup 400per1000 280per1000
au
nenc (236to332)
Ctu
or
llaboraepoint Rescueantiemetics Mediumriskpopulation R(0R.507.6to90.83) 2(2666)1 ⊕mo⊕d⊕er(cid:13)ate2
tioP6
n.fo
Publishrpreve 363per1000 2(25007pteor310010)0
en
dbtin
yg Adverseeffects3 Seecomment Seecomment Notestimable3 - Seecomment
JohnWpostop *Thebasisfor theassumedrisk(e.g.themediancontrol groupriskacross studies) isprovidedinfootnotes. Thecorresponding risk(andits95%confidence interval) isbasedonthe
iley&erativ assumedriskinthecomparisongroupandtherelativeeffectoftheintervention(andits95%CI).
e
Sons,Lnausea CI:Confidenceinterval;RR:Riskratio;
tda
.n GRADEWorkingGroupgradesofevidance
d
vo Highquality:Furtherresearchisveryunlikelytochangeourconfidenceintheestimateofeffect.
m
itin Moderatequality:Furtherresearchislikelytohaveanimportantimpactonourconfidenceintheestimateofeffectandmaychangetheestimate.
g Lowquality:Furtherresearchisverylikelytohaveanimportantimpactonourconfidenceintheestimateofeffectandislikelytochangetheestimate.
(R
e Verylowquality:Weareveryuncertainabouttheestimate.
v
ie
w
) 1Noriskfactorsforpostoperativenauseaandvomitingtypicallyhavecontrolratesof10%;moststudiesinthissystematicreviewhad
highriskpatientswithtwoormoreriskfactorsforpostoperativenauseaandvomiting,thereforeweassumedariskof40%.
2Unexplainedmoderateheterogeneityamongtrialsevenaftersubgroupanalyses.
3 ThetolerabilityofP6acupointstimulationwasgoodwithnocomplaintsofsideeffectsin12studies(1328participants).Otherself-
limitingminorsideeffectsinafewpatientsfromotherstudieswere:redness,irritationandhaematomaatpuncturesitewithacupuncture;
swollenwrists,redindentation,itchingandblisteringatthesiteofthewristbandstud;fatiguewithelectro-acupuncture;mildirritationat
thesiteofcapsicumplasterapplication.
4
BACKGROUND
treatment) in preventing PONV in adults but not in children.
Postoperative nausea and vomiting (PONV)are common com-
However,theseresultsinchildrenwerequestionableastheywere
plaintsaftergeneral,regional,orlocalanaesthesia(Watcha1992),
basedlargelyontrialsinwhichP6acupointstimulationoccurred
with incidences up to 80% (Sadhasivam 1999). Drug therapy
whilethecentralnervoussystemwasdepressedbygeneralanaes-
is only partially effective in preventing or treating PONV (
thesia(White1999).Anothermajorlimitationofourearlierre-
Gin 1994). A systematic review of antiemeticdrugs for PONV
viewwasthatweincludedbothnotreatmentandshamtreatment
(Carlisle 2006) showed that eight drugs effectively prevented
groups.Therefore,wemayhaveoverestimatedthetreatmenteffect
PONVwhencomparedtoplacebo:droperidol,metoclopramide,
ofP6acupointstimulation.
ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine,
andgranisetron.Therelativerisksvariedbetween0.60and0.80, IntheearlierversionofthisCochranereview(Lee2004)of26trials
depending on the drug and the outcome (Carlisle 2006). Evi- (n=3347), weshowedthatthereweresignificant reductionsin
denceforsideeffectswassparse:droperidolwassedative(RR1.32) therisksofnausea(RR0.72,95%CI0.59to0.89),vomiting(RR
andheadachewasmorecommonafterondansetron(RR1.16)( 0.71,95%CI0.56to0.91),andtheneedforrescueantiemetics
Carlisle2006).Morerecently,amultidisciplinarypanelofexperts (RR0.76,95%CI0.58to1.00)intheP6acupointstimulation
producedguidelinesforthepreventionorminimizationofPONV groupcomparedwiththeshamtreatmentgroup.Publicationbias
usingprophylacticorrescuetherapy,eitherseparatelyorincom- mayhaveaffectedtheRRestimatedforpostoperativenauseabut
bination(Gan2007). notforvomiting(Lee2006).
As anaesthetists continue to search for more cost-effective ap-
proachestoimprovingpatientoutcomes,attentionhasfocusedon
simple,inexpensive,andnon-invasivemethodstopreventPONV. OBJECTIVES
Concernaboutthecostandsideeffectsofdrugshasledtointerest
Toassessthepreventionofnausea,vomiting,orrequirementfor
intheuseofalternativeapproachestopreventingemesis.
rescueantiemesis(PONV)byacupointstimulation.
Variousnon-pharmacological techniqueshavebeenexaminedin
WeassessedwhethertherisksofPONVweredifferent:
trialsasalternativestoantiemeticdrugs;theseincludeacupunc-
ture,electro-acupuncture,laseracupuncture,transcutaneouselec-
1. afterP6acupointstimulationcomparedtoshamtreatment,
tricalnervestimulation (TENS),acupointstimulation, acupres-
where’shamtreatment’wasdefinedaseitheradeviceappliedina
sure, and capsicum plaster. Most non-pharmacological studies
non-P6location,oranyattempttoimitate(givetheillusionof)
havefocusedonstimulationofthewristatthe’Pericardium(P6)
P6acupointstimulation;
acupuncturepoint’toreducenauseaandvomiting.TheP6acu-
pointliesbetweenthetendonsofthepalmarislongusandflexor 2. afterP6acupointstimulationforadultscomparedwith
carpi radialis muscles, 4 cm proximal to the wrist crease (Yang children;
1993). The mechanism by which P6 acupoint stimulation pre-
ventsPONVhasnotbeenestablished.Otheracupointsbelieved 3. forinvasiveP6acupointstimulationcomparedwith
topreventPONVincludeShenmen(H7)(Ming2002)andShang noninvasivestimulation,where’invasiveP6acupoint
Wen(CV13)(Somri2001). stimulation’wasdefinedaspenetrationoftheskinatP6
acupoint(withmanualrotationofacupunctureneedle,electrical
BoththeroleandefficacyofP6acupointstimulationinthepre- stimulationofacupunctureneedle)and’noninvasiveP6
ventionofPONVareunclear.Forexample,P6acupointstimula- acupointstimulation’wasdefinedastechniquesthatdidnot
tionsignificantlyreducedtheriskofPONVinsomestudies(Amir requireskinpenetrationattheP6acupoint(acupressure,
2007;Butkovic2005;Ho1996;Rusy2002;Turgut2007;Wang transcutaneouselectricalstimulation,laserdirectedatP6
2002) but not in others (Agarwal 2000; Allen 1994; Barsoum acupoint,capsicumplasteratP6acupoint);
1990; Misra 2005; Shenkman 1999). One systematic review (
Vickers1996),using a’vote counting’ approach, suggested that 4. afterP6acupointstimulationintrialswithlowriskofbias
acupuncture may not be effective in the prevention of PONV. comparedwithunclearorhighriskofbias;
However,thevotecountingapproachisnotconsideredanaccept-
5. afterP6acupointstimulationcomparedwithantiemetic
ablemethodofsummarizing theresultsofasystematicreview(
drugs;
Petitti1994).
6. afteracombinationofP6acupointstimulationand
Ourprevioussystematicreviewoftrials(Lee1999),includingtri-
antiemeticdrugcomparedwithshamtreatment.
alspublishedupto1997,showednodifferencebetweenP6acu-
point stimulation and commonly used antiemeticdrugs in pre- WeassessedtheseeffectsbecausetheNationalInstitutesofHealth
ventingPONVaftersurgery.Thisreviewalsoindicatedthatthe (NIH)issuedastatementthat’acupuncturemaybeusefulasan
techniquewasmoreeffectivethanplacebo(shamtreatmentorno adjunct treatment or an acceptable alternative or included in a
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 5
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
comprehensive management program for many medical condi- cumulativefollow-updatafromtheendofsurgerywereused(in
tions’(NIH1997). thiscase,0to24hours).
Secondaryoutcomes
METHODS
1.Riskofpatientsrequiringarescueantiemeticdrug.
2.Riskofsideeffects.
Criteriaforconsideringstudiesforthisreview
Searchmethodsforidentificationofstudies
Typesofstudies
Allrandomizedcontrolledtrials(RCTs)oftechniquesintendedto
Electronicsearches
stimulatetheP6acupoint,comparedwitheithershamtreatment
or antiemetic drugs, for the prevention of PONV. ’Shamtreat- Wesearchedthefollowingforrelevanttrials.
ment’wasdefinedasadeviceappliedinanon-P6location,orany
• TheCochraneCentralRegisterofControlledTrials
attempttoimitate(givetheillusionof)P6acupointstimulation.
(CENTRAL)(TheCochraneLibrary,Issue3,2008),in
Therefore, for trials that assessed acupressure wristbands, wrist-
Appendix1.
bands without studs placedat theP6acupoint were considered
• Electronicdatabases:MEDLINE(January1966to
asadequateshamtreatmentandthesetrialswereincludedinthe
September2008),inAppendix2;EMBASE(January1988to
review.
September2008),inAppendix3;ISIWebofScience(January
1965toSeptember2008),inAppendix4;andNationalLibrary
Typesofparticipants ofMedicinepublicationlistofacupuncturestudies(http://
All surgical patients without age limitation. The age limits for www.nlm.nih.gov/pubs/cbm/acupuncture.html).
childrenweredefinedbyeachstudy. • Referencelistsofrelevantarticles,reviews,andtrials.
WecombinedthefollowingMeSHandtextwordswith thefil-
Typesofinterventions ters for identifying randomized controlled trials: ’postoperative
TechniquesintendedtostimulatetheP6acupoint:acupuncture, complications’, ’nausea and vomiting’, ’acupuncture’, ’acupunc-
electro-acupuncture,laseracupuncture,transcutaneouselectrical turetherapy’,’acupuncturepoints’,’acupressure’,’transcutaneous
stimulation,anacu-stimulationdevice,acupressure,andcapsicum electricnervestimulator’,and’electro-acupuncture’.
plaster;versusshamtreatmentordrugtherapyfortheprevention There was no language restriction. We excluded studies of P6
ofPONV.Thesediversetechniqueswereconsideredasoneentity acupoint stimulation to treat established PONV, or to prevent
inthemainanalysis,consistentwiththeconceptthatstimulating intraoperativenauseaorvomiting.
thecorrectacupuncturepointismoreimportantthanthenature
of the stimulus (Mann 1987). There was no restriction on the
Searchingotherresources
durationofP6acupointstimulationorwhenitwasapplied.
Wedidnotsearchforconferenceproceedingsorseekunpublished
trials.Greyliteraturehasnotbeenpeer-reviewedandthereissome
Typesofoutcomemeasures evidencethatitisoflowerqualitythanpublishedstudies(McAuley
Wedidseparatemeta-analysesforeachofthefollowingprimary 2000).
andsecondaryoutcomes.Trialscouldreportmorethanonepri-
maryorsecondaryoutcome.
Datacollectionandanalysis
Primaryoutcomes Weselectedtrialsidentifiedbyoursearchthatfulfilledourinclu-
1.Riskofpostoperativenausea. sioncriteria.Therewasnodisagreementbetweenauthorsabout
2. Risks of postoperative vomiting. This was defined as either inclusion andexclusion of studiesfor thisreview. Weexamined
retchingorvomiting,orboth. allselectedtrialsforduplicatedata;wherewefoundduplication,
Postoperativenauseaandvomitingwerenotcombinedaswecould we used the results of the main trial report. We extracted data
notbecertainthatpatientswhovomitedwerealsonauseated.If independently,usingastandardizeddatacollectionform,andwe
theauthorsreportedseveralincidencesof theoutcome measure resolvedanydiscrepanciesindataextractionbydiscussion.Weas-
(forexample0to6hours,6to24hours,0to24hours),thelongest sessedthequalityoftheincludedtrialsindependently,underopen
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 6
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
conditions. Wegradedtheriskofbiasforeachstudyinthedo- Weusedthecontour-enhancedfunnelplottodifferentiateasym-
mainsofsequencegeneration;allocationconcealment;blindingof metryduetopublicationbiasfromthatduetootherfactors(Peters
participants,healthcareproviders,andoutcomeassessors;incom- 2008),usingSTATAstatisticalsoftware(StataCorporation,Col-
pleteoutcomedata;selectiveoutcomereporting;andcomparison legeStation, Texas,version10).Contour-enhancedfunnelplots
ofbaselinecharacteristicsforeachgroupina’Riskofbias’table( displaytheareaofstatisticalsignificanceonafunnelplot(Peters
Higgins2008).Wegradedeachdomainasyes(lowriskofbias), 2008)toimprovethecorrectidentificationofthepresenceorab-
no(highriskofbias),orunclear(uncertainriskofbias)according senceofpublicationbias.Thiswasusedinconjunctionwiththe
tothecriteriaoutlinedintheCochraneHandbookforSystematic ’trimandfill’method(Duval2000)toinformthelikelylocation
ReviewsofInterventions(Higgins2008). of missing studies, using STATA statistical software (Stata Cor-
Wecollecteddataonthetype,duration,andtimingofP6acupoint poration,CollegeStation,Texas,version10),assuggestedbyPe-
stimulation,aswellasthetypeanddoseofprophylacticantiemetic ters(Peters2008).Publicationbiaswouldbeexpectedwhenthe
drug.Werecordeddetailsofthepatientpopulationandtypeof usualfunnelplotisasymmetricalbutassessmentofthecontour-
surgery.WedidnotconsiderfactorssuchastheseverityofPONV enhanced funnel plot indicates that missing studies are located
orthenumberofepisodesofvomiting. wherenonsignificantstudieswouldbeplotted(Peters2008).
Weusedtherandom-effectsmodeltocombinedata,asweexpected We estimated the number needed to treat (NNT) for different
thatthetreatmentsandconditionsinthesetrialswouldbehetero- baselineriskfornauseaandvomitingusingtheRR(Smeeth1999)
geneous.Thismodelincorporatesbothbetween-study(different toassesswhetherP6acupointstimulationisworthwhileforindi-
treatmenteffects)andwithin-study(samplingerror)variability( viduals.Weestimatedthe95%CIaroundthenumberneededto
Mosteller1996).Wecalculatedthepooledrelativerisk(RR)and treatusingthemethodoutlinedbyAltman(Altman1998).
95% confidence interval (95% CI), and analysed heterogeneity
usingtheI2statisticasameasureoftheproportionoftotalvaria-
tionintheestimatesoftreatmenteffectthatisduetoheterogene-
itybetweenstudies.Weconductedsensitivityanalysestoestimate RESULTS
therobustnessofresultsaccordingtosequencegeneration,alloca-
tionconcealment,blindingofoutcomeassessor(adequateversus
inadequateorunclear),selectivereporting(adequateversusinad-
Descriptionofstudies
equateorunclear),andcontroleventrate(≤20%,>20%).We
undertookexploratoryapriorisubgroupanalyses,whichincluded See:Characteristicsofincludedstudies;Characteristicsofexcluded
trialsinadultsversustrialsinchildrenandtrialsaccordingtotype studies.
ofP6acupointstimulation(invasiveversusnoninvasive).Totest The search identified 67 trials of P6 acupoint stimulation for
whetherthesubgroupsweredifferentfromoneanother,wetested PONV.Theflowchart(Figure1)showstheresultsoftheliterature
theinteractionusingthetechniqueoutlinedbyAltmanandBland search(thenumberofhits)andthecullingprocesstoreducethe
(Altman2003). totalto40includedstudies.
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 7
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.
Figure1. Searchingresults
StimulationofthewristacupuncturepointP6forpreventingpostoperativenauseaandvomiting(Review) 8
Copyright©2009TheCochraneCollaboration.PublishedbyJohnWiley&Sons,Ltd.