[lliw]

Though not exactly as you described, something similar was done and published in 2016 (largely leading to this change, since there was not an increase in mortality risk)

http://www.nejm.org/doi/full/10.1056/NEJMoa1515724

One of the main challenges of course in this area is looking at patient outcomes with an incredible amount of potentially confounding variables, since "resident work hours" is just one of the many things that influence patient outcomes at a hospital.

[mattkrause]

The other challenge is that this study is comparing 28 hr shifts with >28 shifts.

This is probably the best that can be done without totally reworking the hospital, but it's not exactly a sensible test: data from lab experiments shows performance cratering well before that.

[ggrothendieck]

There is also the iCompare trial which is underway and to be completed in 2019.