Capture-recapture is a potentially useful method for assessing publication bias

Abstract

<h2>Abstract</h2><h3>Objectives</h3> Publication bias is a problem in systematic reviews of randomized controlled trials. The aim of this study was to assess the influence of publication bias in a systematic review of the effectiveness of Progressive Resistance Training (PRT) in older people. <h3>Study Design and Setting</h3> The relevant studies were ascertained from three sources: electronic databases, experts, and handsearching. Capture-recapture, visual inspection of funnel plots, two statistical tests, and two methods that make adjustments for publication bias, were employed to check the robustness of the conclusions of the systematic review. <h3>Results</h3> The methods employed gave broadly consistent results. Capture-recapture estimated that 3 (95% CI [1,15]) relevant studies were missed, while Trim and Fill suggested 16 studies had been missed. Both Egger's test for bias and a funnel plot regression approach suggested that publication bias was present. A selection model approach suggested that the funnel plot asymmetry observed may not be entirely due to publication bias. <h3>Conclusion</h3> Capture-recapture is a potentially useful method for assessing publication bias. Further research in the form of simulation studies is required, using a variety of scenarios to investigate the extent to which each method approximates the truth.