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So, from the article, it sounds like this current UK system for liver transplant matchibg was developed to replace the previous regional systems. It's not clear if all of those used the same process to determine matches, but it would be possible for them to have developed different processes.

It's also likely that a cross-regional system existed, that may have been ad-hoc. If you had a patient with an exceptional need, you might ask the other regions to be on the look out for an exceptional liver that works just right for your patient. That sort of thing is harder to do in a national system where livers are allocated based on scores.

Another thing that's helpful with multiple systems is it encourages reviewing and comparing results.

For a single system, reviewing results is even more important, but comparing is harder. But you might look at things like demographics of patients who died from liver disease while on the list including how long they were on the list; how long the current people have been waiting; demographics of people who recieve a transplant and how long they waited.

If there's a bias against young people, you would likely see more young people with long wait times, etc.