Dear Andreas,

I thought you might find this book is interesting "Quality Improvement Handbook A Guide for Enhancing the Performance of Health Care Systems".

Not a book but Manley and Jackson have used realist evaluation for this

Historically in the USA, you have to start with Amory Codman, whose work on the improvement of medical outcomes was later incorporated into Medicare.

https://en.wikipedia.org/wiki/Ernest_Amory_Codman