Background: Physical functioning is an important health domain for adults.
Objective: Evaluate physical functioning items in Medicare beneficiaries.
Research Design: Survey data from the 2010 Consumer Assessment of Healthcare Providers and Systems Medicare survey.
Subjects: The 366,701 respondents were 58% female; 38% were 75 or older; 57% had high school education or less.
Measures: Walking, getting in or out of chairs, bathing, dressing, toileting, and eating assessed with 3 response choices: unable to do, have difficulty, do not have difficulty.
Results: Pearson correlations among the 6 items ranged from 0.515 to 0.835 (coefficient α=0.92). A single factor categorical factor analytic model fit the data well (comparative fit index=0.998; root mean square error of approximation=0.083). The item with the highest percentage of respondents reporting no difficulty was eating, followed by toileting, dressing, bathing, getting in and out of a chair, and walking. Threshold parameters from an item response theory–graded response model ranged from −1.983 (between unable to do and have difficulty eating) to −0.551 (between have difficulty and no difficulty walking). Item discrimination parameters ranged from 4.632 (walking) to 8.228 (dressing). IRT-scored physical functioning scores correlated with self-rated general health (r=0.389, n=344,843, P<0.0001) mental health (r=0.296, n=351,254, P<0.0001) and number of chronic conditions (r=−0.229, n=284,507, P<0.0001).
Conclusions: The physical functioning items target relatively easy activities, providing information for a minority of people in the sample with the lowest levels of physical functioning. Items representing higher levels of physical functioning are needed for the majority of the Medicare beneficiaries.
*UCLA Department of Medicine, Los Angeles
†RAND Corporation, Santa Monica, CA
‡Centers for Medicare & Medicaid Services, Baltimore, MD
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Supported by CMS contract HHSM-500-2005-000281 to RAND. R.D.H. was also supported in part by grants from AHRQ (2U18 HS016980), NIA (P30AG021684), NIMHD (2P20MD000182), and NCI (1U2-CCA186878-01).
The authors declare no conflict of interest.
Reprints: Ron D. Hays, PhD, UCLA Department of Medicine, 911 Broxton Avenue, Los Angeles, CA 90024. E-mail: firstname.lastname@example.org.