The Development of a Preference-Based Health-Related Quality of Life Measure for Children Based on the PedsQL: the PedsUtil Scoring System

Abstract

Economic evaluations play a vital role in guiding resource allocation decisions and setting priorities in healthcare. However, a major limitation is the paucity of child-specific preference-based measures of health-related quality of life (HRQoL) that is suitable for use in economic evaluations. No valid and reliable preference-based HRQoL measure currently exists for use across multiple pediatric age groups.

The Pediatric Quality of Life Inventory (PedsQL) is a HRQoL instrument validated for children 2-18 years. The PedsQL, however, is not a preference-based measure, thus cannot be directly used in economic evaluations. Instead, a preference-based scoring system can be developed to estimate health utilities from responses to the PedsQL. The purpose of this dissertation was to construct a novel preference-based scoring system for the PedsQL that can be applied across multiple pediatric age groups: the PedsUtil scoring system.

The first step of constructing the PedsUtil scoring system involved selecting a subset of dimensions and items from the PedsQL to form the PedsUtil health state classification system. The first study (Chapter 2) identified the core dimension structure of the health state classification system. Using data from the Longitudinal Study of Australian Children (LSAC) (n = 45,207), 4 competing dimension structures were evaluated using confirmatory factor analysis. The findings supported a 7-dimension structure (i.e., Physical Functioning, Pain, Fatigue, Emotional Functioning, Social Functioning, School Functioning, and School Absence) of the PedsUtil health state classification system.

The second study (Chapter 3) used Rasch (i.e., item level ordering, differential item functioning, goodness-of-fit, item spread) and psychometric analyses (i.e., internal consistency, floor and ceiling effects), alongside expert panels and key informant interviews, to select the most representative item within each dimension of the PedsUtil health state classification system. All secondary analyses used data from the LSAC. After considering all decision criteria, the full set of PedsQL items was reduced to a core set of 7 items to create the PedsUtil health state classification system. The PedsUtil health state classification was constructed to be suitable for children 2 years and older, including both children with special healthcare needs and typically functioning children.

The third study (Chapter 4) developed and applied a valuation protocol for the preliminary construction of the PedsUtil scoring system. Pilot data on public preferences for child health states defined by the PedsUtil health state classification system were collected from US adults using a discrete choice experiment (DCE) (n = 213) and a time trade-off (TTO) survey (n = 81). DCE pilot data were analyzed using a conditional logistic regression model. The DCE latent coefficients were mapped onto the mean observed TTO health utility values using ordinary least squares regression to anchor the latent coefficients onto the 0-1 QALY scale. Monotonic models were obtained and the relative importance of dimensions was found to vary by age group, highlighting the importance of age-related differences in health state valuations. The PedsUtil scoring system was developed to value HRQoL for 4 pediatric age groups (i.e., 2-4 years, 5-7 years, 8-12 years, 13-18 years).

This dissertation produced the first preference-based HRQoL measure for children 2-18 years. The development of the PedsUtil scoring system enables the inclusion of quality of life impacts for children across a full range of ages in economic and value-based research for the first time, ultimately allowing decision-makers to support more equitable and efficient use of child health services.