Advertisement

Publication bias affected the estimate of postoperative nausea in an acupoint stimulation systematic review

      Abstract

      Background and Objective

      To assess the effect of publication bias and country effect on the results and conclusion of a systematic review of wrist P6 acupoint stimulation for the prevention of postoperative nausea and vomiting.

      Methods

      Reanalysis of a systematic review of 26 randomized trials comparing P6 acupoint stimulation with sham published in the Cochrane Database of Systematic Reviews using the Copas' sensitivity approach.

      Results

      If it is assumed that all studies that have ever been carried out are included, or that those selected for review are truly representative of all such studies, then the estimated relative risk (RR) for nausea was 0.71 (95% CI: 0.58 to 0.88, P<.01) and for vomiting was 0.70 (95% CI: 0.56 to 0.88, P<.01) after adjusting for country effect. For nausea, adjustment for publication bias suggests that the risk has been overestimated. If around 33% of studies have been unpublished, the RR of nausea (0.92, 95% CI: 0.80 to 1.06, P=.25) is no longer significant. For vomiting, however, there is no strong evidence of publication bias. The number of unpublished studies required to substantially overturn the above significant result is implausibly large.

      Conclusion

      Publication bias affects the published estimate of postoperative nausea, not vomiting.

      Keywords

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      Subscribe:

      Subscribe to Journal of Clinical Epidemiology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect

      References

        • Sutton A.J.
        • Song F.
        • Gilbody S.M.
        • Abrams K.R.
        Modelling publication bias in meta-analysis: a review.
        Stat Methods Med Res. 2000; 9: 421-445
        • Sterne J.A.C.
        • Egger M.
        • Smith G.D.
        Systematic reviews in health care: investigating and dealing with publication and other biases in meta-analysis.
        BMJ. 2001; 323: 101-105
        • Thornton A.
        • Lee P.
        Publication bias in meta-analysis: its causes and consequences.
        J Clin Epidemiol. 2000; 53: 207-216
        • Sutton A.J.
        • Duval S.J.
        • Tweedie R.L.
        • Abrams K.R.
        • Jones D.R.
        Empirical assessment of effect of publication bias on meta-analyses.
        BMJ. 2000; 320: 1574-1577
        • Vickers A.
        • Goyal N.
        • Harland R.
        • Rees R.
        Do certain countries produce only positive results? A systematic review of controlled trials.
        Control Clin Trials. 1998; 19: 159-166
        • Tang J.L.
        • Zhan S.Y.
        • Ernst E.
        Review of randomised controlled trials of traditional Chinese medicine.
        BMJ. 1999; 319: 160-161
        • Lee A.
        • Done M.L.
        Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting.
        Cochrane Database Syst Rev. 2004; (CD003281)
        • Begg C.B.
        • Mazumdar M.
        Operating characteristics of a rank correlation test for publication bias.
        Biometrics. 1994; 50: 1088-1101
        • Egger M.
        • Davey S.G.
        • Schneider M.
        • Minder C.
        Bias in meta-analysis detected by a simple, graphical test.
        BMJ. 1997; 315: 629-634
        • Macaskill P.
        • Walter S.D.
        • Irwig L.
        A comparison of methods to detect publication bias in meta-analysis.
        Stat Med. 2001; 20: 641-654
        • Pham B.
        • Platt R.
        • McAuley L.
        • Klassen T.P.
        • Moher D.
        Is there a “best” way to detect and minimize publication bias? An empirical evaluation.
        Eval Health Prof. 2001; 24: 109-125
        • Copas J.B.
        • Shi J.Q.
        A sensitivity analysis for publication bias in systematic reviews.
        Stat Methods Med Res. 2001; 10: 251-265
        • Sterne J.A.C.
        • Egger M.
        Funnel plots for detecting bias in meta-analysis: guidelines on choice of axis.
        J Clin Epidemiol. 2001; 54: 1046-1055