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

BACKGROUND Melasma is a common hyperpigmentation disorder that has 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. The objective of this study was to assess the impact of melasma on quality of life by using a health status measurement - the Dermatology Life Quality Index (DLQI) - and a preference-based measurement - Willingness to Pay (WTP) and Time Trade-Off (TTO). METHODS 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 in this study. The Thai version of the DLQI, questionnaires about WTP, standard TTO, and daily TTO were used to assess patients' quality of life. RESULTS Seventy-seven (98.7%) patients were female with a mean age of 47.8 ± 7.9 years. The mean health utility based on standard TTO was 0.96. The utility obtained by the daily TTO method was 0.92 and was significantly correlated with an economically inactive occupation (p < 0.05). 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 USD ~ 35.1 baht). The WTP was significantly correlated with monthly personal income and the total DLQI score. CONCLUSION The WTP method could be a useful tool with which to measure the quality of life of patients with melasma.