So why does the Panel insist “that the ME/CFS community agree on a single case definition (even if it is not perfect)?” Why must a single case definition be used to study more than one disease or patient population?
I would prefer a single tight definition for initial research, but with enough funding, as I have commented before, a proper research project could use even Oxford. It all depends on how its done, and the funding. A broad definition, with massive investigation, and an emphasis on subgrouping, could be done. The cost is enormous though. A narrow definition is needed to make the problem tractable and doable in reasonable time and with reasonable funding.
This is all tied up in the evidence review. We still do not have enough objective evidence to stratify the disease/s with any certainty.
The ICC comes closest to a research definition that subgroups the patient population, followed by the CCC. Nothing else comes close.
However in even the near future we might indeed have enough evidence, with various big data projects under way and modern systems biology we might well identify distinct as well as overlapping subgroups.
This entire process of making definitions is premature by a few years. Our experts were already using the CCC and ICC, and making research advances using them.