Factors Associated with Patient Preferences for Disease-Modifying Therapies in Multiple Sclerosis

Treatment adherence in patients with multiple sclerosis (MS) is essential to reduce the rate of acute neurological attacks, severity of relapses, and hospitalizations and to slow its progression. Adherence rates in MS patients have been shown to be affected by multiple factors, including physical or cognitive difficulties, perceived lack of treatment efficacy, treatment-related adverse events, injection anxiety, and frequency of administration.

To elicit the preferences of MS patients for noneconomic and economic attributes of current disease-modifying therapies (DMTs).

We used conjoint analysis to estimate preferences from a convenience sample through a web-based online survey. Patients were invited to participate in the study using web portals and newsletters for MS patients. The conjoint survey included the following 6 attributes: (1) overall efficacy based on autoimmune disease progression stabilization; (2) acute increase in disease activity (flare-up); (3) rate of respiratory tract infections; (4) rate of serious respiratory tract infections (leading to hospitalization); (5) medication use; and (6) patient monthly out-of-pocket medication costs. Using a fractional factorial design, 24 product profiles were created. Each respondent reviewed a random selection of 8 profiles. With each profile, subjects were asked to indicate their likelihood to try the hypothetical products on a scale from 0 to 100. Random effects linear regression was used to elicit preferences.

After exclusion of respondents with incomplete information, data from 129 subjects were included in the analysis. The overall relative importance of each attribute for the ranges presented were (1) 38.4% for monthly out-of-pocket cost; (2) 21.5% for route and frequency of administration; (3) 15.9% for risk of hospitalization by infection; (4) 11.9% for risk of respiratory tract infection; (5) 7.4% for risk of flare-ups; and (6) 5.0% for disease progression stabilization. Preference weights indicated that subjects favored subcutaneous (beta coefficient [β] = -2.26, 95% CI = -4.22 to -0.22) and oral administration (β = 7.93, 95% CI = 5.95 to 10.2) over intramuscular (β = -5.67, 95% CI = -8.67 to -3.56), but no significant differences were found between subcutaneous over intramuscular administration. Monthly out-of-pocket cost was the most influential attribute, with an overall relative importance of 38%. The most preferred level was $75 (β = 12.85, 95% CI = 10.64 to 15.06) followed by $150 (β = 3.41, 95% CI = 0.98 to 5.84) when compared between $75, $150, $300, and $450 a month.

Conjoint analysis proved to be a convenient tool to quantify respondents' relative preferences for DMT characteristics. Respondents gave higher weight to DMT monthly out-of-pocket costs and mode of administration than to adverse effects or efficacy. These findings may assist in the development of DMT cost-sharing strategies and shared decision making at the point of care.

No outside funding supported this study. The authors declare no potential conflicts of interest. Study concept and design were contributed by Hincapie and Burns. Data were collected by Hincapie and Burns, and interpreted by all the authors. The manuscript was written by Hincapie, Penm, and Burns and revised by Penm, Hincapie, and Burns. At the time of data collection, Burns was a PhD candidate at The University of Oklahoma, College of Pharmacy.