Sibling psychopathology as a mediator between disability in youth with chronic physical illness and sibling Health-Related quality of life

Chronic physical illnesses (CPIs) can cause significant functional limitations, impacting not only affected youth, but also their siblings. Siblings of youth with chronic physical illness (YwCPI) may experience higher levels psychopathology and poorer health-related quality of life (HRQL). The aim of this study was to assess the mediating role of sibling psychopathology on the association between YwCPI disability and sibling HRQL. Data come from 171 age-matched siblings (mean age: 9.1years, SD = 4.7 years, 44.4% male) of YwCPI (mean age: 9.5 years, SD = 4.2 years, 50.9% male) participating in a longitudinal study. Parents reported on YwCPI disability (WHODAS 2.0), sibling psychopathology (Emotional Behavioural Scales) and sibling HRQL (KIDSCREEN-27) across five time points over 48 months. Linear mixed-effects models were computed to assess mediation, adjusting for sibling age, sex, and time since CPI diagnosis. YwCPI disability predicted increased sibling psychopathology (β = 0.31, p < 0.001), which in turn was associated with lower sibling HRQL. Indirect effects, indicative of mediation, were significant for all HRQL dimensions (β = -0.19 to -0.07, p < 0.05). Findings demonstrated that sibling psychopathology mediates the impact of YwCPI disability on sibling HRQL, highlighting the importance of identifying and targeting mental health difficulties to promote sibling well-being. Findings reinforce the need for integrated family-centred care approaches to pediatric health services and suggest that family-based supports may mitigate adverse psychosocial outcomes in siblings of YwCPI.