One Factor is Disease chronicity as described in “Factors to Consider When Making Benefit-Risk Determinations in Medical Device Premarket Approval and De Novo Classifications” For example if a patient has a chronic disease but they have “adapted to their illness” and it doesn’t effect their daily lives as much they are less likely to tolerate risky devices and is risk averse. Whereas a patient who has a debilitating chronic illness is likely to tolerate a higher risk device. Another factor is the availability of alternate treatments available. So a patient with a life-threatening illness may tolerate more risk for even a small benefit because there aren’t alternatives available.