A recent study from researchers in Spain report that improved pain in back pain patients doesn't always lead to any changes in disability and quality of life. Many studies show that other factors besides pain affect quality of life, but more study is needed to find these.
It may be that your aunt's treatment must focus on improving pain, but also address the areas of mobility, activity, and quality of life. It's likely that separate treatment programs are needed for each area. Improving one doesn't always change the others.