stair lifts greatly help them. They can still go up and down the stairs using the lift and it is very convenient for the carers as they are not going to literally carry the patient or elderly just to go down.
I saw a stair lift when I was working in UK as a nurse that does elderly care at home. One of our clients have stair lift in their house and I would say it increases their mobility and independence too when getting down to the first level.
There are different stair lifts that I've seen to include those that are curve or straight. I heard from those that have it that it makes their life much more easier and they appreciate the independence it gave them. They don't have to catch their breath going up and down their stairs. I bet if in the future we are still living in this two story house we have and we need something like this, I will never hesitate to have it installed.