Development of an Expanded Measure of Physical Functioning for Older Persons in Epidemiologic Research. (October 2015)

• Record Type: Journal Article
• Authors: Gross, Alden L.; Jones, Richard N.; Inouye, Sharon K.
• Is Part Of: Research on aging. Volume 37:Number 7(2015:Oct.)
• Page Start: 671
• Page End: 694
• Publication Date: 2015-10
• Subjects: functioning -- older adults -- item response theory -- ADL -- IADL; Old age -- Periodicals; Gerontology -- United States -- Periodicals; 305.2605
• DOI: 10.1177/0164027514550834
• Languages: English
• ISSNs: 0164-0275

Abstract

We scaled a measure of physical functioning to a population-based normative sample by extending self-reported basic and instrumental activities of daily living with items from the Medical Outcomes Study 12-Item Short Form Survey. We used item response theory to place items administered to a sample of older elective surgery patients on a common metric linked to the Patient Reported Outcomes Measurement Information System (PROMIS) normative sample using published data. The summary measure for physical functioning was internally consistent (Cronbach's α = .83), reliable across a broad range of functioning, and was moderately correlated with walking speed ( r = .52) and energy expenditure ( r = .40). Demonstrating predictive criterion validity, less impaired scores were associated with lower risk of discharge to a rehabilitation facility (odds ratio = .38, 95% confidence interval [CI] [0.22, 0.66]) and shorter hospital stays (incidence rate ratio [IRR] = 0.87, 95% CI [0.79, 0.97]). Our approach may facilitate direct comparison of physical functioning measures across existing and future studies using a common, population-based metric, when overlapping items with the National Institutes of Health (NIH) PROMIS item bank are present.