a1 Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec, Canada
a2 Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
a3 Divisions of Geriatrics and of Clinical Epidemiology, Department of Medicine, McGill University and Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
Background: The Montreal Cognitive Assessment (MoCA) can be used to quantify cognitive ability in older persons undergoing screening for cognitive impairment. Although highly sensitive in detecting mild cognitive impairment, its measurement precision is weakest among persons with milder forms of impairment. We sought to overcome this limitation by integrating information from the Mini-Mental State Examination (MMSE) into the calculation of cognitive ability.
Methods: Data from 185 geriatric outpatients screened for cognitive impairment with the MoCA and the MMSE were Rasch analyzed to evaluate the extent to which the MMSE items improved measurement precision in the upper ability ranges of the population.
Results: Adding information from the MMSE resulted in a 13.8% (13.3–14.3%) reduction in measurement error, with significant improvements in all quartiles of patient ability. The addition of three-word repetition and recall, copy pentagons, repeat sentence, and write sentence improved measurement of cognition in the upper levels of ability.
Conclusions: The algorithm presented here maximizes the yield of available clinical data while improving measurement of cognitive ability, which is particularly important for tracking changes over time in patients with milder levels of impairment.
(Received September 24 2010)
(Revised November 18 2010)
(Revised December 17 2010)
(Accepted December 19 2010)
(Online publication February 01 2011)
c1 Correspondence should be addressed to: Dr. Lisa Koski, Royal Victoria Hospital, R4.74, 687 Pine Avenue West, Montreal, QC H3A 1A1, Canada. Phone: +1 514-934-1934, ext. 34420; Fax: +1 514-843-1734. Email: email@example.com.