Standardized mean differences cause funnel plot distortion in publication bias assessments

eLife

Mira Van Der Naald¹  David W Howells¹  Emily S Sena²  Kimberley E Wever²  Peter-Paul Zwetsloot²  Joanna IntHout³  Steven AJ Chamuleau⁴  Malcolm R MacLeod⁵  Joris AH De Groot⁶ 

[1] Netherlands Heart Institute, Utrecht, Netherlands;Cardiology, Experimental Cardiology Laboratory, University Medical Center Utrecht, Utrecht, Netherlands;Center for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom;Department for Health Evidence, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands;Julius Center for Health Sciences and Primary care, University Medical Center Utrecht, Utrecht, Netherlands;School of Medicine, University of Tasmania, Hobart, Australia;

关键词: meta-analysis;    data simulation;    funnel plot;    publication bias;   

DOI  :  10.7554/eLife.24260

来源: DOAJ

【 摘 要 】

Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, sample size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small sample size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a sample size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results.

【 授权许可】

Unknown