I don't know. I've heard of plenty of failures of it, but it could help. Also must be sort of weird to wear one, at first. Weird and comforting.
It's not just in old age - we could all be or have been caught alone at some point. Out of cell phone range, for example. I had a friend who had a heart attack at 31, so age incidence may be weighted to the high end, but not always.
I remember semi freaking when I realized about lack of cell phone access when I drove from CA to NM. Stupid of me not to understand that in the first place. But, not only did my CA cell not work (it usually did there, except in the densest forest) but none would. Funny how cell phones didn't exist, and then did, and then became needed.
This is an obvious problem for the elderly. I've worried about it myself (put a phone in my basement, back in CA, not for that reason, but I considered that a plus after I did it). But unless you herd us all into barns, I'm not sure the matter is fixable. People will be alone, and sometimes they/we die.
I agree with Nick, depends on if you wear it, and add, paid the bills on it.