Brief assessment of cognitive status in advanced dementia: preliminary results of the Spanish validation of the Severe Mini-Mental State Examination.

Introduction
Cognitive assessment of patients with advanced dementia is a need not adequately covered, so it is necessary to develop tools to obtain information on the cognitive status and resources still available to these subjects. This paper conducts the validation study of the Severe Mini-Mental State Examination (SMMSE) scale in Spanish.

Material and methods
Forty-seven subjects with advanced dementia (Mini-Mental State Examination [MEC] < 11), evaluated with the Reisberg Global Deterioration Scale, MEC, SMMSE and Severe Cognitive Impairment Profile scales participated.

Results
All the items comprising the test showed good differentiability. The test showed high internal consistency (α=0.88), and good test-retest (0.64-1.00; p<0.01) and inter-rater (0.69-1.00; p<0.01) reliability, both for the total score and for each of the items. Construct validity was analyzed by correlation with the SCM (r=0.59; p<0.01). In addition, the sample was divided between subjects with SCM 0-5 and SCM>5, finding that the correlation between SMMSE and SCM scores was significant in the SCM 0-5 group (r=0.55; p<0.05), while it was not significant in those with SCM>5. Likewise, differences in SMMSE scores, but not in SCM, were found between the three SDG groups (5, 6 and 7) (H=11.1; p<0.05).

Conclusions
The SMMSE is an advanced cognitive impairment assessment instrument that extends the lower range of measurement of the SCM avoiding the "floor effect". From our results the instrument can be considered valid and reliable, as well as quick and easy to administer.