Validation of the interRAI Cognitive Performance Scale against independent clinical diagnosis and the Mini-Mental State Examination in older hospitalized patients

Abstract

Objective: To compare the diagnostic accuracy of the interRAI Acute Care (AC) Cognitive Performance Scale (CPS2) and the Mini-Mental State Examination (MMSE), against independent clinical diagnosis for detecting dementia in older hospitalized patients.

Design, setting, and participants: The study was part of a prospective observational cohort study of patients aged ≥70 years admitted to four acute hospitals in Queensland, Australia, between 2008 and 2010. Recruitment was consecutive and patients expected to remain in hospital for ≥48 hours were eligible to participate. Data for 462 patients were available for this study.

Measurements: Trained research nurses completed comprehensive geriatric assessments and administered the interRAI AC and MMSE to patients. Two physicians independently reviewed patients' medical records and assessments to establish the diagnosis of dementia. Indicators of diagnostic accuracy included sensitivity, specificity, predictive values, likelihood ratios and areas under receiver (AUC) operating characteristic curves.

Results: 85 patients (18.4%) were considered to have dementia according to independent clinical diagnosis. The sensitivity of the CPS2 [0.68 (95%CI: 0.58-0.77)] was not statistically different to the MMSE [0.75 (0.64-0.83)] in predicting physician diagnosed dementia. The AUCs for the 2 instruments were also not statistically different: CPS2 AUC = 0.83 (95%CI: 0.78-0.89) and MMSE AUC = 0.87 (95%CI: 0.83-0.91), while the CPS2 demonstrated higher specificity [0.92 95%CI: 0.89-0.95)] than the MMSE [0.82 (0.77-0.85)]. Agreement between the CPS2 and clinical diagnosis was substantial (87.4%; κ=0.61).

Conclusion: The CPS2 appears to be a reliable screening tool for assessing cognitive impairment in acutely unwell older hospitalized patients. These findings add to the growing body of evidence supporting the utility of the interRAI AC, within which the CPS2 is embedded. The interRAI AC offers the advantage of being able to accurately screen for both dementia and delirium without the need to use additional assessments, thus increasing assessment efficiency.