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I would like to make some comments regarding the cost utility analysis in the paper by Hopley et al1 because it is important to understand that the costs should be accounted at the same time and with the same degree of accuracy as outcome data. The economic definition of costs should be used in cost valuation, not the financial definition.2–5 The concept implies that all resources consumed by an intervention should be valued, not just those constituting a budgetary line item.
All methods (that is, cost effectiveness, cost minimisation, cost utility, and cost benefit) of economic evaluation in health care have one principle in common: they examine one or more possible interventions and compare the inputs or resources necessary to carry out such interventions with their consequences or effects.6 Cost utility analysis aimed to compare different interventions in terms of both quantity and quality of life; we express them as utilities. In this case, competing interventions are compared in terms of cost per utility (for example, cost per QALY).6,7 Values of resources in the cost utility analysis are assigned by defining costs. In accounting costs both tangible items (for example, equipment, drugs, materials, money etc) and intangible items (for example, time and treatment mode) must be taken into account, regardless of whether they are used by and accrue to health services, society, or the single individual.6 Costs for some resources may vary because of market forces—for example, rent, exploitation, so it is important to present results not only in monetary terms but also in quantity of resources used.
To allow comparability across different interventions, a 3% discount rate must be used as recommended by most guidelines if economic evaluations are made at different times.7
While this is increasingly becoming the practice, most studies have either attempted to estimate costs for alternative therapies retrospectively or, using literature reviews, budgetary line items and healthcare insurance costs sheets. This should be avoided from economic evaluations because it mainly reflects on budgetary formulations and has very little in common with the real cost of intervention.