Instrumental activities of daily living scale for dementia screening in elderly people.
OBJECTIVE
To develop and validate an Instrumental Activities of Daily Living Scale for elderly people (IADL-E) to use in conjunction with cognitive screening tests for dementia in an educationally and socioculturally heterogeneous population.


METHODS
Eleven IADL items were selected and weighted for major factors causing heterogeneity in the population--gender, education, social (rural/urban) setting and age. Each item was rated for its applicability (yes/no), degree of disability (scored from 0 to 2) and causative impairment (cognitive and/or physical). From this a composite index of cognitive (CDI) or physical (PDI) disability was derived. Validation was performed retrospectively on 240 subjects: 135 without and 105 with dementia by DSM-IV.


RESULTS
The IADL-E had a high internal consistency (alpha = 0.95). The area under the receiver operating characteristic (ROC) curve was 0.97 (CI = 0.94-0.99). A cutoff score of 16 on CDI provided a sensitivity of 0.91, specificity 0.99 and positive predictive value 0.76 (at 5% base rate). IADL-E correlated highly with clinical (DSM-IV, kappa = 0.89), functional (CDR, 0.82) and cognitive (Mini-mental Status Examination, MMSE, 0.74) diagnoses. It showed good responsiveness, with the change on CDI over a median of 23 months correlating significantly with that on MMSE (coefficient = -0.382, CI = -0.667 to -0.098; p=0.009). Individual items had good interrater and test-retest reliability.


CONCLUSIONS
The IADL-E is a reliable, sensitive and responsive scale of functional abilities useful in dementia screening in a socioculturally heterogeneous population.
Mathuranath
P S
PS
Cognition and Behavioral Neurology Center, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India. mathu@sctimst.ac.in
George
Annamma
A
Cherian
P Joseph
PJ
Mathew
Robert
R
Sarma
P Sankara
PS
D000203:Activities of Daily Living / Q000145:classification* / Q000523:psychology; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics / Q000706:statistics & numerical data; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012424:Rural Population / Q000706:statistics & numerical data; D014505:Urban Population / Q000706:statistics & numerical data