Medical Nihilism by Stegenga Jacob;

Author:Stegenga, Jacob;
Language: eng
Format: epub
Publisher: Oxford University Press USA - OSO
Published: 2018-02-14T16:00:00+00:00

8

Measuring Effectiveness

8.1 Introduction

Clinical research is performed to estimate the effectiveness of medical interventions. In this chapter I argue that there are three widespread problems in measuring the effectiveness of medical interventions: the use of poor measuring instruments, the use of misleading analytic measures, and the assumption that measurements in an experimental setting are sufficient to infer a general capacity of effectiveness. Each of these problems contributes to overestimating the effectiveness of medical interventions. The problems suggest corrective principles—medical research should use appropriate measuring instruments, truth-conducive analytic measures, and reliable methods of extrapolation. The application of such principles would generally lead to lower—yet more accurate—estimates of the effectiveness of medical interventions than is presently the case.

By far the most common method for measuring effectiveness of interventions is the randomized trial.1 A randomized trial involves administering an experimental intervention to one group of subjects (the experimental group), administering a placebo or competitor intervention to another group of subjects (the control group), measuring parameters of the subjects, comparing the values of those parameters between the two groups, and if the values of parameters differ between groups, inferring that the intervention has a general capacity to cause that difference. Trials usually have methodological safeguards to minimize systematic error, prominently including the random allocation of subjects to groups, and concealment of the group assignment from both the investigators and the subjects (in Chapter 10 and elsewhere throughout this book I note ways in which such safeguards often fail). These details aside, the measurement of effectiveness involves three steps: the use of a measuring instrument (or a measuring technique more generally), the analysis of measured values, and the extrapolation of analyzed values to a target population.

As argued in Chapters 2 and 3, effectiveness of medical interventions is a capacity to improve the health of patients by targeting disease. This is not an intrinsic causal capacity; effectiveness is a relational property in which the relata are a causal capacity of the intervention and properties of people with a particular disease. The properties that must be modulated by a medical intervention in order for that intervention to be effective are either the constitutive causal basis of a disease or symptoms of a disease that cause harm to those with that disease. In Chapter 2 I call these two individually sufficient conditions for effectiveness causal target of effectiveness and normative target of effectiveness. In Chapters 2 and 3 my aim is to articulate a view of what effectiveness is (a conceptual and metaphysical question), whereas in the present chapter my aim is to articulate methodological problems associated with how we measure effectiveness.

For any measurement one needs a measuring instrument. In clinical practice and medical research many instruments are employed to measure various kinds of parameters, including subjective patient-reported parameters (such as reports of well-being), physician-reported parameters (such as appearance of lethargy), institutional parameters (such as number of days in an intensive care unit), and physiological parameters (such as blood sugar concentrations). For example, the Hamilton Rating Scale for Depression

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