Performance of the Physical Functioning Activities of Daily Living Scale in the 2020 Medicare Health Outcomes Survey

Abstract

Objective: Assessing functional limitations for adults at high risk of frailty yields valuable information for identifying those in need of therapy. We evaluate a self-report measure used to assess physical function among Medicare recipients in the United States.

Design: Secondary analysis of the 2020 Medicare Health Outcomes Survey.

Setting: A random sample of adult enrollees of 510 managed care plans.

Participants: 287,476 adults (37% completion rate): 58% women; 16% were <65 years old (entitled via disability), 50% 65-74, and 34% 75 or older; 77% White, 14% Black, and 8% another race; 19% had <high school education.

Interventions: Not applicable.

Main outcome measure: We evaluate item distributions, dimensionality, monotonicity of response options, reliability, and validity of the 8-item Physical Functioning Activities of Daily Living (PFADL) scale.

Results: Most reported they could do 6 basic activities of daily living without difficulty. More limitations were reported for the other 2 PFADL items: 32% were not limited at all in climbing several flights of stairs and 40% in moderate activities. Product-moment correlations among the 8 items ranged from r=0.19 between the easiest-to-do (eating) and most difficult-to-do (climbing several flights of stairs) items to r=0.73 between bathing and dressing. The coefficient alpha and omega for the 8-item scale were both 0.86. Item slopes ranged from 2.6 (climbing several flights of stairs and eating) to 4.8 (dressing). Item characteristic curves revealed that response options were most likely to be selected in the appropriate order along the physical functioning continuum. The PFADL had at least 0.80 reliability between about -3 SDs below the mean to the mean. It was negatively correlated with comorbid condition count, disability days, problems with balance or walking, falling, and obesity.

Conclusions: The PFADL is useful for assessing average or below physical function in Medicare recipients.

Keywords: Aged; Functional status; Medicare; Rehabilitation; Self-assessment.