Of course this decision is a subjective one. What constitutes quality of life (QOL) for one person may not be the same for someone else. Most people agree that chronic, constant, and/or intense pain can reduce your ability to do things and decrease enjoyment in life.
How much improvement is enough to make it worth having the operation? That question was posed by researchers at the Kenton D. Leatherman Spine Center in Kentucky. They surveyed patients with various degenerative spine diseases before and after lumbar spinal arthrodesis (fusion).
The questionnaires they used were standard self-report instruments well-known in the health care field. Analyzing the data, they were able to come up with a minimum score that would represent improvement needed to show a benefit from the surgery. This was referred to as the clinical benefit threshold. A specific score for each survey was determined to be the clinical benefit threshold.
Using a magnitude of change doesn’t help patients decide whether or not to have the surgery. But it does help point out major improvements afterwards that might not otherwise be recognized.