Rasch analysis of the barthel index in the assessment of hospitalized older patients after admission for an acute medical condition.
OBJECTIVE
To investigate the validity of item score summation for the original and modified versions of the Barthel Index.


METHODS
Rasch analysis of Barthel Index data.


METHODS
General medical wards at 2 acute care hospitals in Australia.


METHODS
Consecutive older medical patients (N=396).


METHODS
Not applicable.


METHODS
Activity limitation was assessed by using the Barthel Index at hospital admission and discharge. At 1 hospital site, the original Barthel Index was used, and at the other hospital site the Modified Barthel Index (MBI) was used.


RESULTS
More than half of the items showed misfit to the Rasch model for both versions of the Barthel Index. The continence items appear to measure a different construct to the other items. After the removal of the continence items, data for the remaining items still did not fit the Rasch model. Neither the original nor the MBI are unidimensional scales. An exception to this occurred when the original Barthel Index was rescored and only then for discharge and not for admission Barthel Index data.


CONCLUSIONS
Because clinicians do not typically rescore outcomes obtained by using the Barthel Index, these findings, combined with unacceptable ceiling effects, render the Barthel Index an assessment tool with limited validity for measuring and monitoring the health of older medical patients.
de Morton
Natalie A
NA
Department of Physiotherapy, Monash University, Victoria, Australia. natalie.demorton@med.monash.edu.au
Keating
Jennifer L
JL
Davidson
Megan
M
D000203:Activities of Daily Living; D000208:Acute Disease; D000223:Adaptation, Psychological; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D004638:Emergency Treatment / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D016330:Frail Elderly; D015577:Geriatric Assessment / Q000379:methods*; D006304:Health Status; D006760:Hospitalization; D006801:Humans; D008297:Male; D010343:Patient Admission; D011594:Psychometrics; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018434:Sickness Impact Profile