Original article
Rasch Analysis of the Barthel Index in the Assessment of Hospitalized Older Patients After Admission for an Acute Medical Condition

https://doi.org/10.1016/j.apmr.2007.10.021Get rights and content

Abstract

de Morton NA, Keating JL, Davidson M. 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.

Design

Rasch analysis of Barthel Index data.

Setting

General medical wards at 2 acute care hospitals in Australia.

Participants

Consecutive older medical patients (N=396).

Interventions

Not applicable.

Main Outcome Measures

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.

Section snippets

Participants

Barthel Index data for Rasch analysis were obtained from participants who were enrolled in the exercise intervention studies reported by de Morton13 and Jones14 and colleagues. Data were collected at 2 acute care public hospitals in Melbourne, Australia. Participants were eligible for inclusion if they were a general medical patient, were 65 years or older, and were assessed within 48 hours of hospital admission. Patients were excluded if they were admitted to the hospital from a nursing home,

Results

In the trial reported by de Morton et al,13 the mean patient age was 78.9±7.5 years. Fifty-five percent were women, and the mean admission Barthel Index score (original version) was 67.3±26.1. In the trial reported by Jones et al,14 the mean patient age was 82.4±7.8 years, 57% were women, and the mean admission Barthel Index score (modified version) was 63.8±23.1. At both hospital sites, admission Barthel Index scores ranged from 0 to 100 out of a maximum possible score of 100. Barthel Index

Discussion

The Barthel Index is widely used as a method for measuring and monitoring changes in activity limitation for older medical patients in the acute care setting.21, 22 However, the results of Rasch analysis in this study indicate that the Barthel Index is not a unidimensional measure of ADL function for this patient population. More than half of the items in both the original and modified versions of the Barthel Index showed misfit to the Rasch model. Therefore, summation of Barthel Index items to

Conclusions

The results of Rasch analysis in this study indicate that the Barthel Index is not a unidimensional measure of ADL function for older acute medical patients, and, therefore, the summation of Barthel Index item scores is not valid in this patient population. In addition, many older acute medical patients have modest limitations in their ADL function, and, therefore, the Barthel Index does not have adequate scale width to accurately monitor changes in ability for these patients. An improved

Acknowledgment

We acknowledge the support of the Clinical Epidemiology and Health Service Evaluation Unit, Melbourne Health who kindly provided their data for secondary analysis in this study.

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    Supported by the National Health and Medical Research Council of Australia (Dora Lush Postgraduate Scholarship no. 280632).

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.

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