From a patient’s long-term perspective, what would it take to disprove the null hypothesis – any form of psychological therapy in the UK healthcare system wouldn’t improve their long-term condition?

I’d guess that to effectively treat patients in the long term, and prevent future suffering, the originating causes need to be addressed. IAW, hold psychological therapy to the same standard of care expected in other medical treatments.

What forms of medicine don’t require an etiological approach, other than psychology and psychiatry?