Measuring Physical Capacity

Abstract

Objective The objective of this study was to develop and assess a composite measure of physical capacity using self-report and physical performance items. Method Item response theory (IRT) is used to evaluate measurement properties of self-report and performance items and to develop a composite measure for 7,609 participants in the National Health and Aging Trends Study. Results Self-reports distinguish differences at the lower end of physical capacity but not at mid-to-high levels. Performance-based measures discriminate across a fuller spectrum. An IRT-based composite score, drawing on both, provides increased measurement precision across the physical capacity spectrum and detects age group differences if either self-report or performance does so—suggesting it is better suited for studying age-related changes than either measure alone. Discussion Self-report and performance measures have different strengths on the physical capacity spectrum. IRT provides a means of combining these different measurement approaches for analyses of physical capacity across a broad range of functioning in later life.

Mobility but Not Balance Limitations Are Associated With Cognitive Decline among Older Hispanics

“…A similar pattern was observed for the side-by-side performers and those unable to do the balance task. While clinical measurement of performance-based tasks is one of the most reliable methods for ascertaining physical function, previous studies have found that a composite measure of survey data with objective clinical measures enables greater discrimination of physical function among the highest and poorest performers ( Kasper et al, 2017 ). Application of survey data to our study may refine the associations observed here by further delineating individuals among the highest and lowest scoring groups of the balance task.…”

Effects of comprehensive geriatric assessment on physical fitness in an acute medical setting for frail elderly patients

“…However, there is a risk of over- and underestimation, recall bias, and social desirability. 50 , 51 One review 52 compiled different instruments for measuring frailty. The physical domain of the frailty syndrome was included in all the studied instruments.…”

Physical Fitness in Hospitalized Frail Elderly Patients

“…Self-reports are often used in large studies because they are easy to administer and capture the patient's own perspective of functioning. However, there is a risk of over-and underestimation, recall bias and social desirability 150,151 .…”

“…Although performance-based measurements for use in clinical settings are less accurate than laboratory-based tests, they have been shown to be applicable and valuable in detecting impairments at an early stage, before they affect overall physical function and become visible in an ADL index 152 . Performance-based measurements have also been found to be able to discriminate across a larger spectrum of physical fitness and to be capable of measuring changes over time to a greater extent, compared with a self-reported ADL-index 150 .…”