Forest plot showing risk difference per 1000 patients

Reproduced from Lau, J., Antman, E.M., Jimenez-Silva, J., Kupelnick, B., Mosteller, F., & Chalmers, T.C. 1992. Cumulative meta-analysis of therapeutic trials for myocardial infarction. N.Engl.J Med., 327, (4) 248-254. Only 8/32 trials from the original meta-analysis forest plot are shown here as illustration.
The forest plots show the conventional and cumulative meta-analyses of trials of intravenous streptokinase for acute myocardial infarction, from Lau (1992). Two extra dimensions have been added to the forest plots in cumulative meta-analysis to convey how the measure changes over time and cumulative number of patients. The forest plot above did not position the intervals for the time dimension or the number of patients correctly; therefore the entities on the vertical axis could be perceived as being equidistant when they are not. This may lead to misperception of the trends ¨C but in fairness, showing trend is not the main intention of the graph.