This is exactly how Nazi Germany started.
It’s called “quality of life” and soon others will make that determination for everyone.
Until “they” have the compliant populace they so desire.
The jump in ethics starts whenever the concept of "health" and "medicine" stops being an ethic of individuals, as it had been for 2400 years in the Hypocratic/Christian ethic, and is transferred to the health of society.
If health applies to an individual, then medicine is used to treat a sick patient and make them healthy. If the health of society is the goal, then medicine can be denied to the individual, or to even make them sicker or die, in order to make the society healthier.
These are naturally very different outcomes, one good and one evil, but it is accomplished with only a slight adjustment to one's ethics, so slight most people don't notice.