Measuring illness perceptions in the family context: psychometric properties of the IPQ-R adapted for adolescent-caregiver dyads.

OBJECTIVES: Given the lack of validated measures assessing illness perceptions in families, the aim of our study was the development and psychometric testing of an adapted version of the Illness Perceptions Questionnaire-Revised (IPQ-R) allowing for Common Sense Model-based dyadic assessment of adolescents' and caregivers' perceptions of a chronic illness in adolescence.

METHODS: Using a cross-sectional survey design, factor structure, reliability and validity of the adapted measure You-IPQ-R were tested in a sample of adolescents with asthma (N = 155) and their primary caregivers (N = 132). Analysis included a dyadic methodology (dyadic confirmatory factor analyses) and examination of the suitability of the measure for different age groups.

RESULTS: Both the adolescent and the caregiver versions of the You-IPQ-R revealed good overall validity and reliability. For all Common Sense Model dimensions except for timeline cyclical in the caregiver version, unidimensional scales aligning with the original IPQ-R structure could be confirmed. Age-specific analyses revealed good to excellent measurement properties in adolescents aged 14 years or older, but considerably poorer indices in younger adolescents.

CONCLUSION: The dyadically validated You-IPQ-R will enable researchers and clinicians to compare illness perceptions in adolescent-caregiver dyads and to assess the effects of family illness perceptions' congruence upon medical, psychosocial and behavioural outcomes.