Reliability and Validity of the International Dementia Alliance Schedule for the Assessment and Staging of Care in Ireland

Objective To independently assess the inter-rater reliability of the International Dementia Alliance (IDEAL) schedule in Ireland and to examine criterion validity for cognitive functioning and caregiver distress. Methods Two raters independently completed the IDEAL schedule based on an interview with persons diagnosed with dementia and their informal caregivers. The Clinical Dementia Rating (CDR) scale and the Zarit Burden Interview were used as reference standards for criterion validity. Intraclass coefficients (ICCs) and correlations (Spearman's ρ) were derived. Results ICCs for the IDEAL subdomains ranged from 0.77 to 1.00, indicating robust agreement between raters. Strong correlations between the CDR and the IDEAL cognitive functioning domain (ρ = 0.82) and overall summary score (ρ = 0.77) were observed. The Zarit Burden Interview and the IDEAL carer distress subdomain were moderately correlated (ρ = 0.56). Conclusion This study confirmed that the IDEAL schedule is a valid and reliable instrument in the Irish population and further supports the international use of the IDEAL schedule.