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LFK index does not reliably detect small-study effects in meta-analysis: A simulation study.

Guido Schwarzer1, Gerta Rücker1, Cristina Semaca2

  • 1Institute of Medical Biometry and Statistics, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany.

Research Synthesis Methods
|March 11, 2024
PubMed
Summary
This summary is machine-generated.

The LFK index test for meta-analysis bias is unreliable, showing unpredictable false positive rates. This simulation study suggests it should not be used for assessing funnel plot asymmetry.

Keywords:
asymmetryfunnel plotmeta‐analysispublication biassimulationsmall‐study effects

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Area of Science:

  • Biostatistics
  • Medical Research Methodology

Background:

  • Funnel plot asymmetry is a key indicator of bias in meta-analysis.
  • The LFK index was proposed as a robust method to detect this bias, irrespective of meta-analysis size.

Purpose of the Study:

  • To evaluate the performance of the LFK index test compared to standard tests for funnel plot asymmetry.
  • To assess the LFK index's reliability across different meta-analysis sizes and heterogeneity levels.

Main Methods:

  • A simulation study was conducted comparing the LFK index test against Egger's test, the rank test, and the Thompson-Sharp test.
  • Simulations varied group sample sizes, number of studies, and between-study heterogeneity.

Main Results:

  • The LFK index test exhibited false positive rates ranging from 0% to nearly 30%, heavily influenced by study number, size, and heterogeneity.
  • Egger's test showed variability under heterogeneity, while rank and Thompson-Sharp tests were often too conservative.
  • The LFK index test's true positive rate was only superior when its false positive rate was already inflated.

Conclusions:

  • The LFK index test's false positive rate is unpredictable and significantly affected by study characteristics and heterogeneity.
  • The current implementation of the LFK index test is not recommended for assessing funnel plot asymmetry in meta-analyses.