The statistic is intended to demonstrate that a concentration of costs among people with out-of-control chronic disease but actually shows the opposite. It shows a diffusion of costs, not a concentration. 60% of adults accounting for 75% of spending — or even the incorrect 50% of adults accounting for 75% of spending — is about as far from a 20-80 rule as one can get. Basically costs are not concentrated in ongoing day-to-day chronic disease.
The bottom line: in a commercial population there is very little cost to be saved by focusing on trying to get more people to take more drugs to control their conditions.
Full post by Al Lewis at The Health Care Blog worth reading.