Response shift in parent-reported disability in children with chronic physical illness: results from the MY LIFE study.

Abstract

Longitudinal assessments of patient-reported outcome measures may be threatened by response shift (RS), a change in individual interpretation of a construct over time. This study tested for RS in parent-reported disability in children with chronic physical illness. Data come from Multimorbidity in Children and Youth across the Life course (MY LIFE). Parent-reported disability was assessed using the 12-item World Health Organization Disability Assessment Schedule (WHODAS) 2.0, which was completed at baseline, 6, 12, 24, and 48-month follow-up. RS in longitudinal changes in WHODAS 2.0 domains (between baseline and 24 months was assessed using Oort's structural equation model. Parents reported on 263 children (9.5 ± 4.2 years; 47.5% female). RS was detected in mobility (reprioritization, uniform and non-uniform recalibration; RS effect size = -0.21) and household activities (uniform recalibration; RS effect size = 0.12). Cognition, society/participation, self-care, and social/getting along exhibited non-uniform recalibration, which affected measurement variance but not bias mean-level change estimates. The impact of RS on the overall assessment of change was small to moderate across domains. Though parents may change their evaluation of disability in their children over time, clinicians can rely on observed scores to assess changes in this population.