Eliciting Quality Adjusted Life Years using the Time Trade Off Method for Prader–Willi syndrome

• Published in: The patient : patient-centered outcomes research 2020-02, Vol.13 (1), p.140-140
• Main Authors: Lavelle, Tara A, Crossnohere, Norah L, Bridges, John F P
• Format: Article
• Language: English
• Subjects: Caregivers; Genetic disorders; Life expectancy; Obesity; Quality of life; Rare diseases
• ISSN: 1178-1653; 1178-1661

Background: Prader-Willi syndrome (PWS) is a rare disease characterized by obesity and insatiable hunger (hyperphagia). There is no cure and it is unknown whether symptom improvement from potential treatments would improve quality-adjusted life years (QALYs) measured with direct elicitation methods. The goal of this study was to examine the acceptance and face validity of using a novel time trade off (TTO) method to value PWS health states, and derive QALYs for these health states. Methods: We developed and fielded an online U.S. national survey to PWS caregivers. We asked caregivers to answer TTO questions to value three health states for a hypothetical 18-year-old with PWS: (1) Untreated PWS, (2) PWS without obesity, (3) PWS without obesity or hyperplasia. In novel TTO questions developed with input from PWS stakeholders, we asked whether it would be better for the hypothetical PWS individual to live 20 additional years in the health state described, or live fewer years completely healthy. We calculated QALYs from TTO values, excluding respondents without answers or with repetitive answers to all TTO questions. We used negative binomial regression analyses to examine how the health state symptoms influenced TTO amounts. Results: Among 458 survey participants, 226 (49%) completed the TTO questions and met eligibility criteria (respondents). Characteristics of respondents were similar to non-respondents. Respondents valued untreated PWS at 0.69 QALYs, PWS with controlled obesity at 0.79 QALYs, and controlled hyperphagia/obesity at 0.92 QALYs. In adjusted analyses, PWS with controlled obesity, and controlled obesity and hyperphagia were associated with significantly higher health state values compared to untreated PWS (p < 0.01). Conclusions: Despite low response rates, using these novel TTO methods to elicit QALYs for PWS demonstrated good face validity, and respondents were similar to non-respondents. PWS health states with controlled symptoms are associated with significantly higher QALYs compared to untreated PWS.