Measuring health-related quality of life in infants and toddlers: conceptual challenges and proposed recommendations

Measuring health-related quality of life (HRQoL) in the very young (i.e., infants and toddlers, aged 0–47 months) presents unique conceptual and methodological challenges. As infants and toddlers cannot reliably self-report their HRQoL, observer inference is necessary. This raises questions about which concepts should be included; how to manage proxy reporting; and how to capture genuine variations in HRQoL, not changes in development or assessment. This commentary outlines six key challenges in measuring infant and toddler HRQoL and details eight proposed recommendations for HRQoL researchers. The piece draws on insights from the EuroQol Toddler and Infant Populations (EQ-TIPS) project, aimed to develop a generic preference-weighted measure (PWM) of HRQoL for infants and children, but has broader applicability to HRQoL measurement in the very young. Key issues addressed include: (i) what concepts to measure; (ii) how to identify which concepts matter to very young children; (iii) managing proxy reporting and reducing bias; (iv) accounting for rapid developmental changes; (v) managing continuity across life-course instruments; and (vi) separating child HRQoL from family spillover effects. Proposed recommendations include greater consensus on a core HRQoL model; prioritising primary caregiver perspectives; justifying and operationalising observable aspects of subjective HRQoL; careful design to capture genuine HRQoL, not developmental change or caregiver spillover; and developing measurement systems to prioritise age-based sensitivity or comparability across time. These recommendations offer a foundation for future consensus-building and research to refine and harmonise best practices in infant and toddler HRQoL measurement, particularly for use in health technology assessment.