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Higher Undercarboxylated to Total Osteocalcin Ratio Is Associated With Reduced Physical Function and Increased 15-Year Falls-Related Hospitalizations: The Perth Longitudinal Study of Aging Women |
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| Authors: | Cassandra Smith Joshua R Lewis Marc Sim Wai H Lim Ee Mun Lim Lauren C Blekkenhorst Tara C Brennan-Speranza Leon Adams Elizabeth Byrnes Gustavo Duque Itamar Levinger Richard L Prince |
| Affiliation: | 1. Institute for Health and Sport (IHES), Victoria University, Melbourne, Australia Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St. Albans, Australia;2. School of Medical and Health Sciences, Edith Cowan University, Perth, Australia Centre for Kidney Research, Children's Hospital at Westmead, School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia Medical School, University Western Australia, Perth, Australia;3. School of Medical and Health Sciences, Edith Cowan University, Perth, Australia;4. Medical School, University Western Australia, Perth, Australia Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Australia;5. Department of Clinical Biochemistry, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Perth, Australia Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Australia;6. School of Medical and Health Sciences, Edith Cowan University, Perth, Australia Medical School, University Western Australia, Perth, Australia;7. Department of Physiology, School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, Australia;8. Medical School, University Western Australia, Perth, Australia Department of Hepatology, Sir Charles Gairdner Hospital, Nedlands, Australia;9. Department of Clinical Biochemistry, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Perth, Australia;10. Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St. Albans, Australia;11. Institute for Health and Sport (IHES), Victoria University, Melbourne, Australia;12. Medical School, University Western Australia, Perth, Australia IL and RLP contributed equally to this work. |
| Abstract: | Evidence from animal models suggests that undercarboxylated osteocalcin (ucOC) is involved in muscle mass maintenance and strength. In humans, the ucOC to total (t)OC ratio may be related to muscle strength and perhaps physical function and falls risk, but data are limited. We tested the hypothesis that ucOC and ucOC/tOC ratio are associated with muscle function (muscle strength and physical function) in older women and 15-year falls-related hospitalizations. Serum tOC and ucOC were assessed in 1261 older women (mean age 75.2 ± 2.7 years) forming the Perth Longitudinal Study of Aging Women (1998 to 2013). Timed-up-and-go (TUG) and grip strength were assessed at baseline and at 5 years. Falls-related hospitalizations (14.5-year follow-up) were captured by the Hospital Morbidity Data Collection, via the Western Australian Data Linkage System. At baseline, women with higher ucOC/tOC ratio (quartile 4) had slower TUG performance compared with quartile 1 (~0.68 seconds, p < .01). Grip strength and 5-year change of TUG and grip were not different (p > .05) between quartiles. Fear of falling limiting house, outdoor, and combined activities was significantly different across quartiles (p < .05). Higher ucOC/tOC was significantly associated with poorer TUG performance at baseline and 5-year change in performance, increased walking aid use, and fear of falling (all p < .05). Higher ucOC was related to lower grip strength at baseline (p < .05) but not 5-year change in strength. Those with the highest ucOC/tOC had greater falls-related hospitalizations (unadjusted log rank, p = .004) remaining significant after adjusting for key variables (hazard ratio [HR] = 1.31, 95% confidence interval [CI] 1.09–1.57, p = .004). We identified a large proportion of older women with high ucOC/tOC ratio who had reduced physical function, including its long-term decline and increased risk of falls-related hospitalizations. Early identification of women at higher risk can enable prevention and intervention strategies to occur, reducing risk for injurious falls. © 2020 American Society for Bone and Mineral Research (ASBMR).. |
| Keywords: | AGING SKELETAL MUSCLE BONE-MUSCLE INTERACTIONS SARCOPENIA |