I think this chart could be really useful. Partly because it is attractively laid out and easy to follow, and partly because I have an issue with the severity scale from the NICE guidelines. In the NICE guidelines, mild disease includes anyone who can work, even part time. I would argue that an illness which prevents you from working more than 10-20 hours a week over the long term is not mild.
It's a shame that the chart forms part of another paper, rather than being the focus of a paper on its own.