Whenever international comparisons are made on quality metrics, inevitably someone complains that the results are invalid because it’s impossible to standardize quality across different systems. Those people are not entirely wrong. It is hard to make sure that you are measuring the exact same thing in different countries. That’s why it’s important to use a variety of metrics, and to acknowledge the limitations in any study and any comparison.
That said, it’s sometimes easier to standardize metrics of access. I talk about this over at the AcademyHealth blog in my latest post. Go read!