[Medical Methods: What Makes them Necessary? Part I: Medical Methods, medical Necessity and its Main Criteria]. / Medizinische Behandlungsmethoden: Was macht sie medizinisch notwendig? Teil I: Medizinische Methoden, medizinische Notwendigkeit und ihre Hauptkriterien.

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 a previous publication we identified MedN as a tripartite predicate: A specific clinical condition requires a specific medical intervention to reach a specific medical goal. Our two-part text searches for and discusses criteria to classify medical methods as generally medically necessary (medn), provided a non-trivial clinical condition and a relevant, legitimate, and reachable goal actually exist. In this paper we present the first part of our results. METHODS: Based on an extensive ethical, sociolegal and sociomedical body of literature, and starting with an non-controversial case vignette (thrombolysis in acute stroke), we generally followed a critical reconstructive approach. First we defined the term "medical method". In several interdisciplinary rounds, we then collected and discussed criteria from three sources: methods to develop clinical practice guidelines as compendia of indication rules, the National Model of Prioritisation in Swedish Health Care, and the HTA Core Model of the European Network for Health Technology Assessment as an instrument of political counselling. RESULTS: We identified general clinical efficacy and benefit as the 2 main "medical" criteria of MedN. As a third - epistemic - criterion, the corresponding bodies of evidence are always to be considered. Since clinical and prioritising guidelines grade their recommendations, the question arises whether MedN should be conceptualised as a dichotomous or finer graded predicate. In accord with German social law we advocate for the binary form. Further discussions focused on multifactorial MedN-configurations, the range of the term, and the variability of evidence requirements. CONCLUSIONS: No matter how the content of MedN is conceptualised, it seems impossible to include its criteria in an algorithm. So deliberative effort is indispensable at any stage of developing a programme to classify medical methods as medically necessary.