Health Baselines and Stated Preferences: Quantifying the Evolution of Preferences Using LCA

Background: Accurate evaluation of treatment preferences in DCEs require defining a clear decision context that asks respondents to consider self-reported or a standardized health baseline. Standardized baselines fix the context and help ensure trade-off plausibility, but also presents a double hypothetical to respondents as they make their choices. Our objective was to compare, at the respondent level, how treatment preferences varied when respondents used their own baseline versus more severe baselines. Methods: A DCE survey was administered to patients and parents of minors (< 18) with sickle-cell disease to evaluate willingness to pursue gene therapy. Respondents answered choice questions for both their self-reported baseline and an assumed, more severe, baseline. Latent classes were identified by cohort and baseline status. Changes in individual respondents class-membership probabilities by actual and hypothetical baselines were used to evaluate how baseline framing affected preference estimates. Results: 174 patients and 109 parents completed the survey. Multiple classes were identified across cohorts by baseline. Class allocation was above 93% for all classes and progressed unevenly with standardized baselines. The relative value of opting out of gene therapy changed with baselines, yet this value varied less across self-reported baselines. A significant difference in preferences found between patients with moderate symptoms and those assuming moderate symptoms was not observed among parents. Conclusions: The analysis of class progression can be an effective tool to evaluate how individual respondents react to changes in choice contexts. Our results indicated that respondent choices accounted for varying baselines. Adaptive behaviors seem plausible given unchanged values for opt out among some respondents with current mild symptoms and some with current moderate symptoms. Overall, we found some support for the use of standardized baselines to represent clinically-relevant choice contexts.