Assessing outcome can be difficult. Measure-based guidance is usually more reliable than general subjective impression. make room for both.
The shared decision making process moves forward when there is agreement that the intervention produced one of the three definitive outcomes: Effective (It worked), Ineffective (it didn't work), or it was intolerable (stopped due to side effect).
Should I continue this intervention or try soemthing different?
Are those symptoms or side effects?
Systematic assessments are the best guidance to answer these questions.