Measuring melasma patients'quality of life using willingness to pay and time trade-off methods in Siriraj Hospital

Abstract

Melasma is a common disorder of hyperpigmentation and causes a significant effect on an individual’s quality of life. However, there is no preference-based measurement that reflects quality of life in patients with melasma. This study aims to measure the impact of melasma on quality of life by using a health status measurement (Dermatologic Life Quality Index, DLQI) and a preference-based measurement [Willingness to Pay (WTP) and Time Trade-Off (TTO)]. A cross-sectional descriptive study was conducted. Seventy-eight patients with melasma who attended the melasma clinic at Siriraj Hospital from February to March, 2009 were recruited into this study. The Thai version of DLQI, questionnaires about WTP, standard TTO, and daily TTO were used to assess patients’ quality of life. Ninety-eight percent of patients were female with a mean age of 47.8 ± 7.9 years. The quality of life based on standard TTO was 0.96. The quality of life obtained by daily TTO method was 0.92 and significantly correlated to occupation. The mean monthly WTP for the most effective treatment was 1,157 baht (7.2% of monthly income), ranging from 100 to 5,000 baht ($1 = 35.1 baht). The mean monthly WTP was significantly correlated to monthly personal income. The impact on patients’ quality of life from WTP method was significantly correlated to age, occupation and total DLQI score. In conclusion, WTP method could be a useful tool to measure the quality of life of patients with melasma.