Measuring Health : On the Theoretical Foundations of Health Status Evaluations

Abstract: This thesis is about the notions of health and pathology in medical theory. I develop a theory, which defines ‘health’ and ‘pathology’ in a way that solves several problems with earlier suggestions of how to define these terms. I call the theory ‘the disposition profile efficiency theory’, abbreviated ‘the DPE-theory’. According to the DPE-theory, a trait token (e.g. an organ) is healthy, roughly, if and only if all of its dispositions for performing physiological functions are efficient enough. A trait token is pathological, roughly, if and only if at least one of its dispositions for performing a physiological function is not efficient enough. The notion of efficiency, I suggest, is reference class-relative: the efficiency of a trait token’s disposition for performing a physiological function expresses a relation between the trait token and a health standard for the trait token’s bearer’s reference class.The thesis also examines the most discussed theory of health and pathology, “the biostatistical theory” proposed by Boorse. Both the DPE-theory and the biostatistical theory are evaluated against a number of desiderata: the theory should (i) be theoretically sound; (ii) only use empirical, statistical, and logical terms; (iii) not involve values; (iv) be clear; (v) both account for health and pathology as reference class-relative properties, and account for the importance of integration of different physiological functions for health; and (vi) have reasonable implications. It is argued that the DPE-theory satisfies the desiderata, and that it does so better than the biostatistical theory.The main contributions of the thesis are the DPE-theory’s models of dispositions, its approach to defining reference classes, its efficiency measure, and its way of drawing the line between high enough efficiencies and too low efficiencies. Other important contributions concern the desideratum about reasonable implications. It is shown how the DPE-theory contributes to solving two much discussed objections directed towards the biostatistical theory, “the problem of common diseases” and “Kingma’s dilemma”. Further, the DPE-theory is used to illuminate discussions about certain types of conditions for which it is contested whether they should count as healthy or pathological.