Methodological issues in estimating the cost of epilepsy.

Changes in treatment alternatives and the emphasis on cost containment and managed care have increased the interest in information on the cost of epilepsy. The last comprehensive cost study in the USA was in 1975. That study estimated the national cost of epilepsy at $3.6 billion for 2.1 million cases. On a per patient basis the 1975 figure represents $7440 in 1995 US dollars, $1150 (15%) for direct treatment-related costs and $6290 (85%) for indirect employment-related costs. Since then, various cost-of-illness (COI) studies in the USA and other countries have offered estimates ranging from $6000 to $15000 per patient per year, with percentages of direct and indirect cost varying greatly. To assist those interested in interpreting or producing cost information, this paper reviews the state of research on the cost of epilepsy and discusses several methodological issues. A comprehensive study begun in 1993 to update the 1975 estimates for the USA is also described. Recommendations are provided to stimulate discussion about the best methods to use in future research.