Common errors and controversies in pharmacoeconomic analyses.

The need to demonstrate the cost effectiveness of healthcare interventions has led to a rapid increase in the use of economic tools within pharmaceutical evaluations. Pharmacoeconomics is employed at many stages of the evaluation process, helping to predict which products are likely to be economically viable at an early stage, and providing information to aid price and reimbursement negotiations as well as formulary and purchasing decisions in conjunction with phase III and IV clinical trials. The ability of economic evaluations to accurately determine the best use of society's scarce resources, however, is strongly influenced by the existence of areas of confusion, controversy and dispute which hinder the researcher at every step. A good economic evaluation requires a number of ingredients including: (i) relevant, good quality clinical data, raising issues of trial design, sample size and perspective; (ii) relevant costs and outcomes, measured, valued and discounted credibly and accurately; (iii) appropriate methods of data analysis (statistical, incremental and sensitivity); and, once the trial is over, (iv) presentation of the results in a way which maximises the generalisability of the results and, hence, the usefulness of the research. None of these areas are trouble-free but with understanding and openness, mistakes can be minimised.