Using journal impact factors to correct for the publication bias of medical studies.

Publication bias of the results of medical studies can invalidate evidence-based medicine. The existing methodology for modeling this essentially relies upon the symmetry of the funnel plot. We present a new method of modeling publication bias that uses this information plus the impact factors of the publishing journals. A simple model of the publication process enables the estimation of bias-corrected intervention effects. The procedure is illustrated using a meta-analysis of the effectiveness of single-dose oral aspirin for acute pain, and results are also obtained for five other meta-analyses. The method enables the fitting of a wide range of models and is considered more flexible than other ways of compensating for publication bias. The model also provides the basis of a statistical test for the existence of publication bias. Use of the new methodology to supplement existing methods is recommended, in the context of a sensitivity analysis.