Development and validation of a parent-proxy bronchiectasis child quality-of-life instrument: the BC-QoL

Quality of life (QoL), the highest prioritised outcome by children with bronchiectasis and their parents, is a patient-reported outcome measure increasingly considered essential when evaluating health and interventions. Despite this, there are no validated instruments that specifically measure QoL related to bronchiectasis in children. We aimed to develop and validate a new bronchiectasis child-specific parent-proxy QoL instrument (BC-QoL).

We developed a draft 44-item BC-QoL and subsequently conducted a prospective cohort study in which 142 parents completed the draft BC-QoL and six other measures (two validated cough scores; the Parent-proxy Children's Acute Cough-specific QoL questionnaire; the Depression, Anxiety and Stress Scale - 21-items; the RAND-36; and the Pediatric Quality of Life Inventory (PedsQL™ 4.0)) to assess the convergent and discriminant validity of the BC-QoL. The questionnaires were completed over 3 weeks at different phases of a child's illness (stable state, exacerbation and/or recovery). Responses were analysed using psychometric and clinical impact techniques to reduce the number of items and determine the instrument's reliability and validity. The minimal important difference (MID) was also calculated.

The final 23-item BC-QoL instrument with its three domains (emotional, physical and social well-being) demonstrated high split-half reliability (0.95), Cronbach's alpha (0.97), repeatability (intraclass coefficient 0.74, 95% CI 0.62-0.82), validity and responsiveness. BC-QoL's domains significantly correlated with those of the PedsQL™ 4.0 (Spearman correlations: emotional=0.43, social=0.41, physical=0.47). BC-QoL's MID ranged from 0.74 to 1.32.

This study provides evidence supporting the validity and reliability of BC-QoL. The BC-QoL can be used to evaluate the impact and effectiveness of interventions and better understand the disease burden among children with bronchiectasis.