[Medical Methods: What Makes them Medically Necessary? Part II: Further Criteria, Overuse, Moving Thresholds, and Grey Zones].

Objectives: "Medical necessity" (MedN) is a fuzzy term. Our project aims at concretising the concept between medical ethics, social law, and social medicine to support health care regulation, primarily within Germany's statutory health insurance system. In Part I, we identified efficacy, (net)benefit, and the corresponding bodies of evidence as obligatory criteria of MedN. This is the second part suggesting and discussing further criteria.

Methods: See Part I RESULTS: (Part II): As further MedN-criteria we critically assessed a method's effectiveness and acceptance in routine care, its potential beneficiaries, theoretical fundament, cost, and being without alternative as well as patients' self-responsibility, cooperation, and preferences. Since MedN has both lower and upper bounds, we had to consider certain cases of mis- and overuse, due for instance to "indication creep" or "disease mongering".

Conclusions: The additional criteria neither establish MedN (when met singly or together) nor exclude it (when not met). If MedN is rejected in view of the 3 obligatory criteria then further information does not overturn the verdict. If a method is already assessed as being medn then further criteria do not make it "more or less necessary". Though we advocated for a binary MedN-concept (Part I) we are nonetheless convinced that not all medical methods deemed medn are equally medically relevant. Respective differences within the range of MedN could be assessed by techniques to prioritise medical conditions, methods, and aims.