Willingness to pay: a feasible method for assessing treatment benefits in epilepsy?

Contingent valuation using willingness to pay (WTP) is one of the methods available for assessing the value of a new technology or treatment for a disease in monetary terms. Experience with this method is lacking in epilepsy. The objectives of this study were to assess the acceptability of the WTP method in epilepsy, the level of the responses, and to investigate its validity by comparison with other non-monetary preference measures. Among 397 patients with epilepsy responding to a comprehensive questionnaire, 82 were randomly selected for an interview. They were asked about their WTP for an imaginary new technology which could permanently cure their epilepsy. Fifty-nine patients participated and 57 completed the interview (32 women; mean age 44 years), the majority with well-controlled epilepsy. The patients indicated a median WTP of Norwegian Kroner (NOK) 150,000 (USD 20,000; GBP 11,800), interquartile range NOK 50,000-350,000 (USD 6, 667-46, 667; GBP 3,937-27,559) for this cure. Non-response was low, indicating high acceptability of this method. There was little association between WTP and other preference measures; the Spearman rank correlation coefficient was -0.09 and -0.12 with time trade-off and standard gamble respectively, questioning the validity of this method.