I wonder whether it matters as to how those requiring CPR ended up in hospital in the first place: did they suffer a cardiac event outside of hospital, and arrive at hospital with CPR being continued, as opposed to those who were in hospital to begin with, but suddenly required CPR for whatever reason?
That line in itself seems to suggest that the likelihood of CPR being successful increases slightly when a victim is transported to hospital with CPR continuing throughout from the time of their cardiac event, versus those who never make it to hospital, because the CPR givers stop (exhausted, unable to continue) or because efforts before reaching hospital are considered pointless/time-of-death called (as it was clear to medical professionals that CPR isn't going to bring a clearly dead person back to life).
That line in itself seems to suggest that the likelihood of CPR being successful increases slightly when a victim is transported to hospital with CPR continuing throughout from the time of their cardiac event, versus those who never make it to hospital, because the CPR givers stop (exhausted, unable to continue) or because efforts before reaching hospital are considered pointless/time-of-death called (as it was clear to medical professionals that CPR isn't going to bring a clearly dead person back to life).