The Journals of Gerontology Series A: Biological Sciences and Medical Sciences Advance Access published online on January 30, 2009
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, doi:10.1093/gerona/gln033
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Development and Validation of a Short Portable Sarcopenia Measure in the African American Health Project
1 Center for Aging Research, Indiana University, Indianapolis
2 Regenstrief Institute, Inc., Indianapolis, Indiana
3 Department of Neurology & Psychiatry, School of Medicine, Saint Louis University, Missouri
4 Health Services R&D Service, Department of Veterans Affairs Medical Center, Gainesville, Florida
5 College of Public Health and Health Professions, University of Florida, Gainesville
6 Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
7 Department of Physical Therapy and Athletic Training, Edward and Margaret Doisy College of Health Science, Saint Louis University, Missouri
8 Department of Medicine and Pediatrics, Washington University School of Medicine, St. Louis, Missouri
9 Iowa City VAMC and College of Public Health, University of Iowa, Iowa City
Address correspondence to Douglas K. Miller, MD, IU-Center for Aging Research, 410 West 10th Street, Suite 2000, Indianapolis, IN 46202. Email: dokmille{at}iupui.edu
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Abstract |
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Background.: Poor muscle size and function (sarcopenia) have an important role in the age-associated disability process. However, no commonly accepted index of sarcopenia exists for use in epidemiological studies.
Methods.: A cohort of 998 community-dwelling African Americans 49–65 years’ old at baseline was used to construct the short portable sarcopenia measure (SPSM). SPSM was conceptualized as a measure of sarcopenia that combines estimates of muscle quantity and function into a single scale, is based on component items that can be obtained easily in the field, represents muscle status at a single time point that can be used without sex-specific adjustments, and can be used to follow change in muscle status over time with each person as his or her own control. We used exploratory factor analysis (EFA) to identify a unidimensional scale based on timed chair rises, lean mass, and grip strength divided by height. We used these three items and their EFA factor weights to construct SPSM (mean 9.0, median 9, range 0 [worst] to 18 [best] at baseline). Construct validity of the new measure, over a period of 36 months was examined.
Results.: SPSM required 8.5 pounds of equipment and 12.4 minutes to complete. It showed good score distribution and convergent, discriminant, and predictive validity with measures of muscle function, body composition, physical performance, psychological factors, and functional limitation cross-sectionally and with muscle function and body composition longitudinally. Extensive sensitivity analyses confirmed SPSM's robustness.
Conclusions.: SPSM is a brief, portable, and valid measure of sarcopenia for use in epidemiological research. Similar studies in other populations are needed.
Keywords Aging; Muscles; African Americans; Disability
Received: September 7, 2007; Accepted: September 23, 2008