This is a Consort Diagram done with SAS SGPLOT. You will see this in a Clinical trial report, representing the overview flow of patients through the stages of the trial. The PolygonPlot function makes it simpler to do this diagram. Other functions you will need are, SeriesPlot and TextPlot. Working out the co-ordinates is probably the most challenging (boring) part of the process.
There are several examples online of different techniques in both SAS and R that you can google to learn more. And there is also the ggconsort R package. This is quite new I believe and I am not sure how adequate the current version is?
 Â