Publication Bias in Meta-Analysis

Publication bias is the term for what occurs whenever the research that appears in the published literature is systematically unrepresentative of the population of completed studies. Simply put, when the research that is readily available differs in its results from the results of all the research that has been done in an area, readers and reviewers of that research are in danger of drawing the wrong conclusion about what that body of research shows. In some cases this can have dramatic consequences, as when an ineffective or dangerous treatment is falsely viewed as safe and effective. This can be illustrated by two events that received much media attention as this book was going to press in late 2004. These are the debate surrounding Merck’s recall of Vioxx, a popular arthritis drug (Merck maintained that it recalled Vioxx as soon as the data indicated the high prevalence of cardiovascular events among those who took Vioxx for more than 18 months, while media reports said that Merck hid adverse event evidence for years), and the use of selective serotonin reuptake inhibitor (SSRI) anti-depressants among adolescents (Elliott Spitzer, attorney general of New York State, filed a 2004 lawsuit against GlaxoSmithKline,