There is no hard and fast answer to this question. There are several very individual factors that must be weighed before deciding when to place a loved one into long term care. Basically, these factors involve the following: 1) The severity of your loved one's illness process; 2) Your own resources (Can they reasonably and safely be kept at home?); and 3) Your ability to cope with your loved one living at home.
The disease process is often much more severe than people account for. There are several scales together called Activities of Daily Living that break down the impact disease process has on interfering with daily life, such as toileting, eating, etc. Many people have the romanticized notion that they will be able to care for their loved one at home but fail to take into account how debilitated their loved one is. Using a well-defined scale such as an Activity of Daily Living Scale will help to bring reality closer to home and to better assess the impact that disease process has on an illness.
Additionally, the reality is that there are so many multiple demands on people today that you may not have the resources to watch over a loved one, whether they are at your home or their own. Resources refer to time, energy, money, and emotional wherewithal. It is important to keep in mind all of these variables. Yes, you may be able to take care of them at home. But, if you yourself are in poor health or are constantly exhausted, how much stimulus and love and support will you really be able to offer? Many caregivers find that they are so stressed that they constantly snap at their loved one, hurting them emotionally.
We are not trying to make the case for putting a loved one into a long term care facility. We are making the case for keeping them where they can be cared for safely, lovingly, and timely. If this can be done at home, that is most certainly the best place for a loved one to be.