Читать книгу Clinical Pharmacology and Therapeutics - Группа авторов - Страница 141

Cost, in a health economic evaluation, comes in many forms and is more than the simple acquisition cost of the drug in question.

One of the key concepts in economic evaluation is that of opportunity cost. This is defined as the benefit foregone when selecting one course of action rather than another. When resources are limited, the decision to spend money in one way means that we cannot spend the money on something else, and therefore are foregoing the benefits associated with the thing we can no longer do. In a competitive market, opportunity costs should be reflected by market prices, but where they are not (as is usually the case in healthcare systems), opportunity costs have to be estimated by economists.

Economists also distinguish between direct, indirect and intangible costs. Direct costs are those that are consumed in the provision of a health intervention, e.g. staff costs, hospital operating costs, drug acquisition costs. These are generally easy to measure. Indirect costs relate to costs from a societal perspective, for example, the loss of earnings or costs borne by patients and their carers as a consequence of illness. These costs are more difficult to measure and are not always included in economic evaluations. Intangible costs relate to things like pain, worry and distress caused by illness; these are very difficult to quantify in monetary terms and are often only described rather than quantified in economic evaluations.

The last distinction to note is the importance of marginal costs, rather than average costs, in economic evaluation. An example to explain this concept is to envisage a new treatment that results in a patient being able to be discharged from hospital a day earlier than the current treatment allows. It might seem that the average cost of this bed day saved should be incorporated into the analysis but from an economist's point of view, the average cost would overstate the savings that arise. This is because, unless the hospital ward can be closed, the fixed costs (such as staff costs, heat and light) will still be incurred. The marginal cost of the bed day is a better reflection of the resource change brought about by the new treatment as this will take into account only the costs that change, for example, the savings in the patient's meals, drugs and perhaps some small savings in staff time.