Screening for preexisting cognitive impairment in older intensive care unit patients: use of proxy assessment

OBJECTIVES: To determine the prevalence of preexisting cognitive impairment (CI) in patients admitted to the medical intensive care unit (ICU) and compare two different proxy measures of preexisting CI in ICU patients. DESIGN: Cross-sectional comparative study. SETTING: Urban university teaching hospital. PARTICIPANTS: One hundred thirty patients aged 65 and older admitted to the medical ICU. MEASUREMENTS: Two previously validated proxy measures of CI: the Modified Blessed Dementia Rating Scale (MBDRS) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). RESULTS: The prevalence of preexisting CI in the ICU, determined using a combination of the measures, was 42%. Agreement between the two CI measures was 86%, with a kappa of 0.69, with discrepancies being related to the different domains measured by each instrument. CONCLUSION: There is a high prevalence of preexisting CI in patients admitted to the medical ICU. Both the MBDRS and IQCODE can be used to screen for preexisting CI in situations where direct patient assessment is not feasible. Future studies are needed to address physician recognition of CI and its effect on patient care decisions and outcomes.