Feasibility and construct validity of the parent willingness-to-pay technique for children with juvenile idiopathic arthritis

Objective. To assess the feasibility and construct validity of the willingness-to-pay (WTP) technique for measuring health care preferences in families of children with juvenile idiopathic arthritis (JIA). Methods. Parents were asked to estimate the monthly US dollar amount they would be willing to pay to obtain for their child the following hypothetical drugs: ARTHRO, which guarantees complete clinical response; and NO-STOM-ACHE, a drug that eliminates gastrointestinal (GI) symptoms. A yes/no question was used with random assignment of the starting bids. Parents who agreed to pay the starting bid were then asked whether they would be willing to pay 200% and then 400% of this initial bid. Socioeconomic data and information on medications, disease activity, patient physical function, wellbeing, and health-related quality of life (HRQOL) were obtained. Results. Sixty-two families of children with JIA were interviewed. GI symptoms were present in 54%, and 53% of the children had joints with active arthritis or limited range of motion. Four parents (7%) were unwilling to pay anything for any of the studied medications. The mean amount (median; mean percentage of available family income) families were willing to pay was $395 ($300; 15%) for ARTHRO and $109 ($80; 4%) for NO-STOM-ACHE. Correlation and regression analysis supported that, adjusted for the available family income, the WTP for ARTHRO was associated with disease activity, pain, and the HRQOL of the patients. After correction for the starting bids and the available family income, the WTP for NO-STOM-ACHE was associated with the patient's HRQOL, pain, and the amount of GI discomfort. Conclusion. The WTP technique is feasible and has construct validity for measuring health care preferences for children with JIA. Relatively large WTP estimates support a possible important negative impact of the disease on families of children with JIA.