Assessing the experimental EuroQol toddler and infant populations (EQ-TIPS) descriptive system: a protocol integrating discrete choice experiment (DCE) surveys in instrument development.

IntroductionThe experimental EuroQol Toddler and Infant Populations (EQ-TIPS) instrument is currently under development as a health-related quality of life (HRQoL) measure for toddlers and infants aged 0-36 months. Using this protocol, researchers can conduct surveys with discrete choice experiments (DCEs) that examine the key properties of HRQoL instruments, specifically whether severity aligns with preferences across each attribute and the extent to which attributes influence choices. To demonstrate this protocol, we will conduct two waves of DCE surveys using different choice tasks and a common scenario (a 1-month health episode for a 1-year-old child).Methods and analysisIn the first wave (a general population sample of 400 Australian adults; 14 kaizen tasks each), respondents will view a single EQ-TIPS-five-level (v3.0) profile for each task and be asked to make a series of choices that sequentially alleviate the child's health problems. Using this exploratory evidence, we will assess whether EQ-TIPS severity aligns with preferences and the extent to which each attribute level influences choices (ie, main effects). In the second wave (1000 Australian adults; 28 paired comparisons), respondents will see two EQ-TIPS profiles for each task and be asked to choose between them. Using this confirmatory evidence, we will compare the main effects and their uncertainty by wave. For each DCE, we will estimate a main-effects conditional logit model and test for differences in effects using cluster bootstrap techniques. As sensitivity analyses, we will evaluate the effects of task sequence, attribute order and sample size on uncertainty in each wave.Ethics and disseminationThe independent review board at Includovate evaluated the application for ethical clearance and approved the study on 19 February 2025. To disseminate our findings, we will prepare multiple manuscripts for publication in peer-reviewed journals and present highlights at scientific meetings, such as the EuroQol Plenary Meeting and the International Academy of Health Preference Research.