Costing methodology in laparoscopic surgery.

This paper provides some basic insights in economic evaluation and costing methodology by means of illustrations in the field of laparoscopic surgery. Some general methodological aspects are discussed, as well as their impact on the calculation of both societal and hospital costs of medical interventions. First, Health Care Technology Assessment is described, and several techniques of economic evaluation in health care are situated in this area. Two fundamental concepts in costing analysis are discussed : opportunity costs and marginal (or incremental) analysis. Furthermore, it is argued that in designing an economic analysis, sufficient attention should be given to delineating the alternative treatment options and to determining the perspective from which the study is performed (patient, hospital, insurer, society,...). Subsequently, it is argued that all price and wage data for activities performed within a certain period should apply to the same time period. Finally, in order to facilitate overview, re-calculation and interpretation of cost data, it is advised to distinguish fixed from variable costs. Different categories of societal costs are described, as well as a number of methodologies for their evaluation. In calculating hospital costs, the costs of all different resources used (e.g. buildings, equipment, staff, materials) must be identified precisely. The issues of annuitising initial investment expenses, calculating operating and maintenance costs, and allocating labour and overhead costs are discussed. Finally, it is argued that, in all studies, it should be investigated whether the results of the economic analysis are robust to the models' assumptions, by means of sensitivity analysis. This paper provides a practical toolkit for medical doctors, to allow a correct understanding and critical analysis of economic literature in the field of laparoscopic surgery.