Willingness to pay for improvement of physical function among rheumatoid arthritis patients as measured by Health Assessment Questionnaire

The main objective of this study was to assess the symptoms and functional difficulties caused by rheumatoid arthritis through application of the willingness to pay (WTP) method. Structured questionnaire study was conducted among 242 RA patients. The subjects were asked to evaluate their functional capacity using visual analog scales (VAS) for all the 20 questions in the Health Assessment Questionnaire (HAQ). Each VAS was followed by a question asking how much the respondent would be willing to pay on a monthly basis for a 50% improvement with the function in question. These were combined with later collected data on clinical status and use of RA-related health services. The average WTP varied greatly in the examined 20 different functions. The total WTP average on a 50% improved functional capacity amounted to € 567.05 per month. Patients with lower functional capacity (HAQ 1.2 or more) were ready to contribute significantly (p < 0.001) more (705 euros/month) than those with better functional status (199 euros/month). Subjects, whose financial standing was better, reported a higher total WTP (r = 0.218, p < 0.01). On average, the total WTP of the respondents equaled 18.44% of the disposable net monthly income per person of the household. However, the variation was quite substantial. WTP among patients with rheumatoid arthritis was best depicted through the functional capacity of the patient, the possible time the patient had retired, and the global feeling of pain. In conclusion, monetary value is a concrete way of portraying subjective valuation. WTP method is suitable for assessing functional deficits of rheumatoid arthritis.