Oral Virtual Presentation (Virtual only) ESA-SRB-ANZBMS 2021

Osteocalcin, Muscle Function and 15-year Falls-related Hospitalizations in Older Women: The Perth Longitudinal Study of Ageing Women (#147)

Cassandra Smith 1 2 , Joshua R Lewis 3 4 5 , Marc Sim 3 4 , Wai Lim 4 6 , Ee Mun Lim 7 8 , Lauren Blekkenhorst 3 4 , Tara C Brennan-Speranza 9 10 , Leon Adams 4 11 , Elizabeth Byrnes 7 , Gustavo Duque 2 12 , Itamar Levinger 1 2 , Richard Prince 4 8
  1. Institute for Health and Sport (iHeS), Victoria University, Melbourne, VIC, Australia
  2. Australian Institute for Musculoskeletal Sciences (AIMSS), University of Melbourne, Melbourne, VIC, Australia
  3. School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
  4. Medical School, University of Western Australia, Perth, WA, Australia
  5. Centre for Kidney Research, Children's Hospital at Westmead, School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
  6. Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Australia
  7. Department of Biochemistry, Queen Elizabeth II Medical Centre, Perth, Western Australia, Australia
  8. Department of Endocrinology and Diabetes, Fiona Stanley Hospital, Perth, WA, Australia
  9. Department of Physiology and Bosch Institute for Medical Research, University of Sydney, Sydney, NSW, Australia
  10. School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
  11. Department of Hepatology, Sir Charles Gairdner Hospital, Perth, WA, Australia
  12. Department of Medicine- Western Health, University of Melbourne, Melbourne, VIC, Australia

Purpose: Undercarboxylated osteocalcin (ucOC) is suggested to be involved in muscle mass maintenance and strength, at least in animal models. In humans, the ucOC to total osteocalcin (tOC) ratio may be related to muscle function, a term combining muscle strength and physical function, and possibly falls risk, but the data is limited. We tested the hypothesis that ucOC and ucOC/tOC ratio are associated with muscle function and 15-year falls-related hospitalisations in older women.

Methods: Serum OC and ucOC was assessed in 1261 older women (mean age 75.2 ± 2.7 years) at year-1 of the Calcium Intake Fracture Outcome Study trial, forming the Perth Longitudinal Study of Ageing Women (PLSAW, 1998 to 2013). Timed-up-and-go (TUG) and grip strength was assessed at baseline (1998) and at 5 years. Falls-related hospitalisations over a 14.5-year follow-up was captured by the Hospital Morbidity Data Collection, via the Western Australian Data Linkage System.

Results: At baseline, women with higher ucOC/tOC ratio (quartile 4) had slower TUG performance compared to quartile 1 by 0.68 secs (~0.68 secs, p<0.01); grip strength and 5-year change in TUG and grip was not significantly different (p>0.05). Higher ucOC/tOC ratio was significantly associated with poorer TUG performance at baseline and 5-year change in performance (all p<0.05). Those with the highest ucOC/tOC had greater falls-related hospitalisations (unadjusted log rank p=0.004) that remained significant after adjusting for key variables (HR 1.31, 95% CI 1.09-1.57, p=0.004).

Conclusions: We identified many older women with high ucOC/tOC ratio that also have poorer physical function, including its long-term decline and increased risk of falls-related hospitalisation. This data supports the concept that quantifying ucOC/tOC ratio could be used as a predictor of these adverse outcomes, possibly enabling early intervention and minimising future fall risk. This should be explored in future.