Psychometric Properties of a Scale to Assess the Severity of Bathing Disability
Abstract
Gill TM, Gahbauer EA, Van Ness PH. Psychometric properties of a scale to assess the severity of bathing disability.
Objective
To develop and evaluate the psychometric properties of a new bathing disability scale.
Design
Reliability and validity study.
Setting
General community.
Participants
Two subsets of community-living older persons, selected from an ongoing longitudinal study, who had some degree of bathing disability or were at increased risk for bathing disability, as determined during a comprehensive assessment at 36 (N=199) and 54 (N=213) months, respectively.
Interventions
Not applicable.
Main Outcome Measures
The bathing disability scale was administered at 36, 54, and 72 months, and changes in scores were assessed between 36 and 54 months and 54 and 72 months, respectively, for the 2 subsets of participants. Convergent construct validity was evaluated by comparisons with changes in activity of daily living (ADL) disability, mobility disability, and the Short Physical Performance Battery (SPPB). Discriminative construct validity was determined by comparisons according to age and physical frailty. Responsiveness was evaluated by comparisons between participants who had and had not been hospitalized and, subsequently, by plotting correlations according to the timing of these hospitalizations.
Results
The test-retest reliability was high, with an intraclass correlation coefficient=0.76 (95% confidence interval=0.59−0.94). The internal consistency reliability was excellent with Cronbach α=0.91−0.97. Changes in scores on the bathing disability scale were positively correlated with changes in scores in ADL and mobility disability and inversely correlated with changes in scores on the SPPB. A greater decline in scores was observed among the oldest old and those who were physically frail, but these differences did not consistently achieve statistical significance. The scale was responsive to the occurrence and/or timing of intervening hospitalizations.
Conclusions
The bathing disability scale is reliable, valid, and responsive and may be suitable for use in clinical trials to evaluate the effectiveness of interventions to enhance independent bathing.
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
Correspondence to Thomas M. Gill, MD, Yale University School of Medicine, Adler Geriatric Assessment Center, 20 York St, New Haven, CT 06504
Supported by the Patrick and Catherine Weldon Donaghue Medical Research Foundation (grant no. DF07-009), the National Institute on Aging (grant no. R01AG022993), and a Midcareer Investigator Award in Patient-Oriented Research grant from the National Institute on Aging (grant no. K24AG021507). The study was conducted at the Yale Claude D. Pepper Older Americans Independence Center (grant no. P30AG21342). None of the funding organizations played any role in the design, conduct, or reporting of the study or in the decision to submit the study for publication.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.
ABSTRACT