Consistency between willingness to pay for reducing the risk of adverse drug events and the associated health-related utility gain
- Presenter:
Chair: Albert Okunade; Discussant: Albert Okunade Wed June 7, 2006 9:45-11:15 Room 225
Rationale: Adverse drug events (ADE) have an impact on health utility, and individuals are willing to pay to reduce the risk of suffering such events. Objectives: The objective of this study is to assess the consistency between the willingness to pay (WTP) for reducing the risk of adverse drug events and the associated health-related utility gain. The study quantifies the monetary value of reducing the risk of incidence of mild ADE and measure the health-related utility gain for such a reduction.
Methodology: Personal interviews were completed for 174 people in Madrid (Spain). Upon definition of a payment card, individuals were asked for the amount of money they would be willing to pay to reduce the risk of incidence of ADE. Using Standard Gamble, individuals were also asked for the health-related utility gain they would derive from a reduction in the probability (p) of occurrence of ADE. Consistency among the preference relation, the willingness to pay (WTP) to reduce the risk of ADE and the health-related utility gains was assessed. Consistency between the WTP for different risk reductions and the level of risk reduction of the same ADE was also evaluated.
Results: Gastrointestinal distress and heartburn (GI) was ranked as less preferred than skin rash (SR) by 99.4% of interviewees. Interviewees were willing to pay annually an average of 379.51_ to avoid GI (CI 325.40_ - 433.62) and 148.40 (CI 118.58_ - 178.22) to avoid SR. Interviewees were willing to pay 223.49 (CI 187.34_ - 259.64) for an 80% GI risk reduction, and 79.37 (CI 57.20_ - 101.55) for an 80% SR risk reduction. Interviewees were willing to pay 162.45 (CI 128.94_ - 195.96) for a 50% GI risk reduction and 49.25 (CI 30.47_ - 68.03_) for a 50% SR risk reduction. Interviewees considered the health-related utility gain (1-p) derived from the avoidance of GI 0.67 (CI 0.28- 0.35) higher than the health-related utility gain attributed to the avoidance of SR 0.09 (CI 0.07- 0.12). The WTP and the stated health-related utility were consistent for SR (Pearson correlation coefficient = -0.283, p-value <0.01). The Pearson correlation coefficient was not statistically significant in the case of GI.
Conclusions: The willingness to pay amount was consistent with the stated preference relation, and it was also consistent for different levels of risk reduction in the incidence of ADE. The willingness to pay was not proportional to the size of the risk reduction. The value of a health gain may differs depending on the method applied for each assessment.
