Willingness to pay for a treatment for pain in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease that affects 240 per 100 000 Canadians. Of these patients, 10-80% (average 70%) experience pain. Sativex is a cannabis-based drug recently approved for neuropathic pain.

In this study, we determine individuals' preferences between two treatment options as well as the willingness to pay (WTP) for Sativex, expressed as the amount they would pay in insurance premiums to have access to that treatment.

The WTP instrument comprised a decision board as a visual aid, and a questionnaire. A decision board helps clinicians standardize the presentation of treatment information. In this study, the decision board described two treatment options: a three-drug combination (gabapentin, amytriptyline, acetaminophen [paracetamol] {i.e. pills}) and the three-drug combination plus Sativex (i.e. 'pills and oral spray'). Information on efficacy and adverse effects was taken from trial data; wording was guided by a panel of neurologists and tested for clarity on lay people. The instrument was administered to 500 participants from Canada's general population using the bidding game approach. Descriptive statistics were calculated.

Mean (SD) age of participants was 39 (13) years, with a female : male distribution of 56 : 44. The decision board was presented in both English (85%) and French (15%). Of 500 interviewees, 253 (50.6%) chose the 'pills and oral spray'. Mean monthly WTP for the insurance premium for those who chose the 'pills and oral spray' was Can dollars 8 (SD +/- 15, median 4, range 0-200).

Assuming that 51% of the general population are willing to pay additional premiums as reported in this study, the premiums collected would cover the cost of Sativex for all Canadian MS patients experiencing pain, with a surplus.