OBJECTIVES:

A common criticism of utilities derived from vignettes is that there is little evidence to support the validity of the vignettes as descriptions of the health state. It is generally preferred to estimate utilities from patients directly but in a rare disease this is challenging which means vignette methods are often used. Specific values in Late-onset Pompe disease (LOPD) which quantify the impact on health-related quality of life (HRQL) with disease progression are lacking. Here we present a study where vignettes were derived from subjective data from patients with LOPD.

METHODS:

Item-level response data from patient-reported outcomes (including the Rasch-built Pompe-specific activity measures or R-PAct) were summarised for each of nine health states in an economic model. States were defined by increasing requirements for respiratory and/or mobility support. Vignette content was augmented using findings from a literature review, and testimonials. The draft vignettes were then reviewed in debriefing interviews with patients with LOPD and healthcare professionals (HCPs).

RESULTS:

Available trial data only included ambulatory patients with approximately half needing no respiratory/mobility support. Non-ambulatory states were extrapolated using information from interviews with 9 patients and 2 HCPs plus the literature review findings. Participants described the impact of the condition on work and relationships, daily activities, dependence, frustration, anxiety and depression. They also described the burden and benefit of using assistive technology. Following the interviews, the severity of symptoms and impacts including anxiety and social impact was altered in some vignettes, and the additional impact of frustration was included.

CONCLUSIONS:

The content of vignettes was initially based entirely on validated PRO data which supported their content validity. All subsequent changes were verified by patients with LOPD. We believe that this represents a significant improvement on standard methods of vignette development and should improve utility estimation in rare diseases.