Objectives: To examine the frequency distributions and interrater reliability of individual items of the interRAI Acute Care instrument.
Design: Observational study of a representative sample of older inpatients; duplicate assessments conducted on a subsample by independent assessors to examine interrater reliability.
Setting: Acute medical, acute geriatric and orthopedic units in 13 hospitals in nine countries.
Participants: Five hundred thirty-three patients aged 70 and older (mean age 82.4, range 70-102) with an anticipated stay of 48 hours or longer of whom 161 received duplicate assessments.
Measurements: Sixty-two clinical items across 11 domains. Premorbid (3-day observation period before onset of the acute illness) and admission (the first 24 hours of hospital stay) assessments were conducted.
Results: The frequency of deficits exceeded 30% for most items, ranging from 1% for physically abusive behavior to 86% for the need for support in activities of daily living after discharge. Common deficits were in cognitive skills for daily decision-making (38% premorbid, 54% at admission), personal hygiene (37%, 65%), and walking (39%, 71%). Interrater reliability was substantial in the premorbid period (average kappa=0.61) and admission period (average kappa=0.66). Of the 69 items tested, less than moderate agreement (kappa<0.4) was recorded for six (9%), moderate agreement (kappa=0.41-0.6) for 14 (20%), substantial agreement (kappa=0.61-0.8) for 40 (58%), and almost perfect agreement (kappa>0.8) for nine (13%).
Conclusion: Initial assessment of the psychometric properties of the interRAI Acute Care instrument provided evidence that item selection and interrater reliability are appropriate for clinical application. Further studies are required to examine the validity of embedded scales, diagnostic algorithms, and clinical protocols.