Standardisation of costs: the Dutch Manual for Costing in economic evaluations.

The lack of a uniform costing methodology is often considered a weakness of economic evaluations that hinders the interpretation and comparison of studies. Standardisation is therefore an important topic within the methodology of economic evaluations and in national guidelines that formulate the formal requirements for studies to be considered when deciding on the reimbursement of new medical therapies. Recently, the Dutch Manual for Costing: Methods and Standard Costs for Economic Evaluations in Health Care (further referred to as "the manual") has been published, in addition to the Dutch guidelines for pharmacoeconomic research. The objectives of this article are to describe the main content of the manual and to discuss some key issues of the manual in relation to the standardisation of costs. The manual introduces a six-step procedure for costing. These steps concern: the scope of the study;the choice of cost categories;the identification of units;the measurement of resource use;the monetary valuation of units; andthe calculation of unit costs. Each step consists of a number of choices and these together define the approach taken. In addition to a description of the costing process, five key issues regarding the standardisation of costs are distinguished. These are the use of basic principles, methods for measurement and valuation, standard costs (average prices of healthcare services), standard values (values that can be used within unit cost calculations), and the reporting of outcomes. The use of the basic principles, standard values and minimal requirements for reporting outcomes, as defined in the manual, are obligatory in studies that support submissions to acquire reimbursement for new pharmaceuticals. Whether to use standard costs, and the choice of a particular method to measure or value costs, is left mainly to the investigator, depending on the specific study setting. In conclusion, several instruments are available to increase standardisation in costing methodology among studies. These instruments have to be used in such a way that a balance is found between standardisation and the specific setting in which a study is performed. The way in which the Dutch manual tries to reach this balance can serve as an illustration for other countries.