I don't know why you think that risk stratification of the treated group has nothing to do with the non treated group. The treated group were far more likely to die or have complications than the average, yet with treatment of the identified drugs and supplement actually were considerably less sick .
You cannot say the treated group, even with risk stratification is far more likely to die. The very fact that these people presented to an outpatient clinic and not, say, a hospital would indicate they were not the sickest people out there.
Simply put, without knowing anything about the comparison group, you don’t know if the comparison group is average risk, above average or below average.