The Reaction to Diagnosis Questionnaire-Sibling Version: A Preliminary Study on the Psychometric Properties.

Background: The diagnosis of a disability in a child may significantly impact the entire family system. While existing literature has primarily focused on parental reaction to the diagnosis, little is known about how typically developing siblings process this event.

Methods: This exploratory study presented the preliminary psychometric properties of the Reaction to Diagnosis Questionnaire-Sibling Version, adapted from an instrument originally designed to assess parental reaction to the child's diagnosis. Following a back-translation and adaptation process, a cross-sectional study was conducted on 623 typically developing siblings (M = 24.6 years, SD = 5.76) of individuals with neurodevelopmental disorders or physical disabilities.

Results: Exploratory factor analyses supported a refined 32-item questionnaire with two factors-lack of resolution versus resolution, both showing excellent internal reliability. No significant differences were found based on typically developing sibling sex, age, or type of disability of the brother/sister, while correlational analyses indicated that greater disability severity was associated with lower resolution and higher lack of resolution.

Conclusions: Results suggested that the Reaction to Diagnosis Questionnaire-Sibling Version is a promising tool for assessing the reaction to the brother/sister diagnosis on behalf of the typically developing siblings. Further research is needed to confirm these results and inform intervention programs promoting well-being and adaptive family functioning.