PHILADELPHIA Willingness-to-pay studies, widely used in managed care and health policy studies to assess patient priorities, can tell dermatologists a lot about what psoriasis patients really want from their therapies, Matthew Delfino Jr. said at the annual meeting of the Society for Investigative Dermatology.
Mr. Delfino, a medical student at Harvard Medical School, Boston, has been working with the department of dermatology at Brigham and Women's Hospital to bring the skills and methodologies he learned during his business administration training to the management of skin disease.
"Willingness-to-pay [WTP] studies elicit both stated preferences, as well as unstated preferences. Higher willingness to pay is associated with stronger desire or preference for relief or improvement in a particular aspect of life," he explained.
The concept is simple: Investigators interview patients and ask them a series of questions along the lines of "Assuming a hypothetical ideally effective therapy, how much would you be willing to pay out of pocket for complete elimination of the impact or impairment of psoriasis on this particular domain of your life?"
It is akin to asking someone how much he or she would be willing to pay for an umbrella. If it is raining, and the individual's perceived need is pressing, he or she will likely be willing to pay more than if the sun is shining. "Greater impact on quality of life correlates with greater willingness to pay," Mr. Delfino explained.
Working with dermatologists at the hospital, he designed a WTP question panel that could evaluate patients' willingness to pay for alleviation of psoriasis-related impairment in eight life domains: intimacy, sleep, physical comfort, social comfort, emotional health, ability to work or participate in volunteer efforts, ability to maintain self-care, and ability to concentrate.
They recruited 40 patients with a history of psoriasis for participation in face-to-face interviews. The subjects had a mean age of 51.5 years; 83% were white and 48% were female; 60% were college educated, and 55% had annual incomes of more than $45,000.
In addition to the WTP questions, patients were also asked to rate their overall health and their psoriasis-related health on a 1- to 10-point visual analog scale.
In general, the patients were healthy, or at least they perceived themselves to be. As a group, they had an overall health score of 7.25. On psoriasis-related issues, they had a mean score of 5.4, indicating that they rated their dermatologic health considerably lower than their total health.
In terms of WTP responses, the four most important life domains for these patients were physical comfort, social comfort, emotional health, and ability to maintain self-care. The mean amount patients would be willing to pay for total elimination of physical symptoms was $2,000, with a range from $500 (the bottom price quartile) to $5,500 (the 75th quartile). Similarly, for total emotional health, the patients would be willing to pay a mean of $2,000, with a range of $250$5,000.
At the other end of the priority spectrum, ability to sleep and ability to concentrate seem to be little affected by psoriasis. Patients were willing to pay a mean of $625 (range $50$5,000) for total relief of sleep problems and $875 (range $25$3,850) for elimination of any concentration problems associated with psoriasis.
These priorities were generally consistent across gender, age, and socioeconomic parameters. In fact, the investigators were surprised that education level and income had no measurable impact on the patients' WTP responses. Mr. Delfino noted that men were slightly more likely than women to report psoriasis-associated sleep problems, but there were no gender-associated differences in WTP for relief of sleep-related issues.
In general, the patients' priorities, as indicated by their WTP responses, correlated well with their perceived psoriasis-related and total health scores.
As a methodology, WTP assessment does have its limitations. "You are, in effect, 'monetizing' health outcomes, which can be very tricky," Mr. Delfino acknowledged. Further, studies like this rely almost exclusively on patient self-evaluation, which is always somewhat questionable. That said, the WTP approach is generally accepted in health policy literature, and advocates believe it can reveal important information about patients' real-world experiences, desires, and preferences that cannot be obtained through other lines of questioning.
Mr. Delfino said that the Brigham group is continuing to explore ways to apply WTP methodology in psoriasis. The next step is to go back to the medical records of patients in the study cohort and determine if there are any correlations between disease severity, duration, body surface area involvement, or other measures of psoriasis and the patients' response to the WTP questions.