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STANDARDIZED PHYSICAL FUNCTIONING THROUGH ITEM RESPONSE THEORY ACROSS STUDIES OF OLDER ADULTS
Journal article   Open access   Peer reviewed

STANDARDIZED PHYSICAL FUNCTIONING THROUGH ITEM RESPONSE THEORY ACROSS STUDIES OF OLDER ADULTS

N Armstrong, L N Gitlin, J M Parisi, M C Carlson, G W Rebok and A L Gross
Innovation in aging, v 2(Suppl 1), pp 400-400
11 Nov 2018
url
https://academic.oup.com/innovateage/article-pdf/2/suppl_1/400/26477742/igy023.1491.pdfView
Published, Version of Record (VoR) Open
url
https://doi.org/10.1093/geroni/igy023.1491View
Published, Version of Record (VoR) Open

Abstract

Abstracts
Common scales for physical functioning are not directly comparable without harmonization techniques, complicating attempts to pool data across studies. We derived a standardized metric for physical functioning in older adults with item response theory methods to place 232 basic and instrumental activities of daily living questions, administered across eight intervention studies of older adults (N=2,556), and scaled to NIH PROMIS norms. Model-estimated item thresholds were widely distributed across the range of physical functioning. The lowest precision in each dataset was 0.80. The sample size needed to detect 25% physical functional decline with 80% power based on the physical functioning factor was less than half of what would be needed using an average z-score. Item-level harmonization enables direct comparison of physical functioning measures across existing and future studies and across levels of function using a nationally representative metric.

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