Melbourne Medical School Collected Works - Research Publications
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ItemOperational definitions of sarcopenia and their associations with 5-year changes in falls risk in community-dwelling middle-aged and older adults(SPRINGER LONDON LTD, 2014-01)UNLABELLED: Sarcopenia may be diagnosed in the clinic using operational definitions based on low muscle mass or function. This prospective, population-based study revealed that sex-specific associations may exist between operational definitions of sarcopenia and falls in community-dwelling middle-aged and older adults. INTRODUCTION: The objective of this study is to verify associations between sarcopenia and falls risk and to determine changes in sarcopenia prevalence over 5 years in middle-aged and older men and women according to different anthropometric and performance-based operational definitions. METHODS: N = 681 volunteers (48% female; mean ± SD age 61.4 ± 7.0 years) participated in baseline and follow-up assessments (mean 5.1 ± 0.5 years later). Appendicular lean mass (ALM) was assessed by dual-energy X-ray absorptiometry, hand grip (HGS) and lower-limb (LLS) strength were assessed by dynamometry, and falls risk was determined using the physiological profile assessment. Anthropometric definitions (ALM/height squared [ALM-H], ALM/weight × 100 and a residuals method [ALM-R]) and performance-based definitions (HGS, LLS and upper- and lower-limb muscle quality [LMQ]) of sarcopenia were examined. The lowest 20% of the sex-specific distribution for each definition at baseline was classified as sarcopenia. RESULTS: Sarcopenia prevalence increased after 5 years for all operational definitions except ALM-H (men: -4.0%; women: -5.5%). Men classified with sarcopenia according to anthropometric definitions, and women classified with sarcopenia according to performance-based definitions, had significant increases in falls risk over 5 years (all P < 0.05) compared to individuals without sarcopenia. Significant sex interactions were observed for ALM-R, LLS and LMQ (all P < 0.05) definitions. CONCLUSIONS: Sarcopenia prevalence generally increases at a higher rate when assessed using performance-based definitions. Sarcopenia is associated with increases in falls risk over 5 years in community-dwelling middle-aged and older adults, but sex-specific differences may exist according to different anthropometric or performance-based definitions.
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ItemEffects of a Targeted Multimodal Exercise Program Incorporating High-Speed Power Training on Falls and Fracture Risk Factors in Older Adults: A Community-Based Randomized Controlled Trial(WILEY, 2014-01)Multimodal exercise programs incorporating traditional progressive resistance training (PRT), weight-bearing impact training and/or balance training are recommended to reduce risk factors for falls and fracture. However, muscle power, or the ability to produce force rapidly, has emerged as a more crucial variable to functional decline than muscle strength or mass. The aim of this 12-month community-based randomized controlled trial, termed Osteo-cise: Strong Bones for Life, was to evaluate the effectiveness and feasibility of a multimodal exercise program incorporating high-velocity (HV)-PRT, combined with an osteoporosis education and behavioral change program, on bone mineral density (BMD), body composition, muscle strength and functional muscle performance in older adults. Falls incidence was evaluated as a secondary outcome. A total of 162 older adults (mean ± SD; 67 ± 6 years) with risk factors for falls and/or low BMD were randomized to the Osteo-cise program (n = 81) or a control group (n = 81). Exercise consisted of fitness center-based HV-PRT, weight-bearing impact and challenging balance/mobility activities performed three times weekly. After 12 months, the Osteo-cise program led to modest but significant net gains in femoral neck and lumbar spine BMD (1.0% to 1.1%, p < 0.05), muscle strength (10% to 13%, p < 0.05), functional muscle power (Timed Stair Climb, 5%, p < 0.05) and dynamic balance (Four Square Step Test 6%, p < 0.01; Sit-to-Stand, 16%, p < 0.001) relative to controls. There was no effect on total body lean mass or mobility (timed-up-and-go), and no difference in falls rate (incidence rate ratio [IRR], 1.22; 95% confidence interval [CI], 0.72-2.04). In conclusion, this study demonstrates that the Osteo-cise: Strong Bones for Life community-based, multimodal exercise program represents an effective approach to improve multiple musculoskeletal and functional performance measures in older adults with risk factors for falls and/or low BMD. Although this did not translate into a reduction in the rate of falls, further large-scale trials are needed to evaluate the efficacy of this multimodal approach on reducing falls and fracture.
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ItemSerum selenium status in Graves' disease with and without orbitopathy: a case-control study(WILEY, 2014-06)OBJECTIVE: Selenium is effective in improving quality of life and reducing the progression of active Graves' orbitopathy. The effect of correcting relative selenium deficiency on improving Graves' orbitopathy is unknown, as baseline selenium levels have not previously been measured. The study aims to determine whether serum selenium levels are reduced in patients with Graves' disease with orbitopathy (GO) compared with without orbitopathy (GD). DESIGN: A prospective, case-control study performed between 2009 and 2012 at endocrine and ophthalmology clinics in Australia. PATIENTS: A total of 198 patients with Graves' disease participated in the study: 101 with Graves' orbitopathy and 97 without Graves' orbitopathy. MEASUREMENTS: Serum selenium levels in both groups. RESULTS: Mean serum selenium levels were significantly lower in GO (1·10 ± 0·18 μm) than in GD (1·19 ± 0·20 μm) (P = 0·001). Mean selenium levels appeared to decrease in parallel with increasing severity of GO; selenium level was 1·19 ± 0·20 μm in GD, 1·10 ± 0·19 μm in moderate-to-severe GO and 1·09 ± 0·17 μm in sight-threatening GO (P = 0·003). Serum selenium levels remained significantly lower in GO after adjusting for age, smoking status, thyroidectomy, radioactive iodine treatment and residential location. CONCLUSION: Serum selenium levels are lower in patients with GO compared with GD in an Australian study population with marginal selenium status. Relative selenium deficiency may be an independent risk factor for orbitopathy in patients with Graves' disease.
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ItemShining the Light on Sunshine: a systematic review of the influence of sun exposure on type 2 diabetes mellitus-related outcomes(WILEY, 2014-12)Prospective observational studies uniformly link vitamin D deficiency with the incidence of type 2 diabetes mellitus (T2DM), yet trials supplementing participants at risk of T2DM with vitamin D to reduce progression to T2DM have yielded inconsistent results. Inconsistencies between supplementation trials may be due to insufficient dosing or small sample sizes. Observational studies may also have reported spurious associations due to uncontrolled confounding by lifestyle or genetic factors. Alternatively, observational and intervention studies may not be entirely comparable. Observational studies show an association between higher vitamin D status, which is predominantly derived from sun exposure, and decreased incidence of T2DM. Trials intervene with vitamin D supplementation, and therefore may be missing alternate causes of the effect of sun exposure, as seen in observational studies. We propose that sun exposure may be the driving force behind the associations seen in observational studies; sun exposure may have additional benefits beyond increasing serum 25-hydroxyvitamin D (25OHD) levels. We performed an electronic literature search to identify articles that examined associations between sun exposure and T2DM and/or glucose metabolism. A best evidence synthesis was then conducted using outcomes from analyses deemed to have high methodological quality. Ten eligible full-text articles were identified, yielding 19 T2DM-related outcomes. The best evidence analysis considered 11 outcomes which were grouped into six outcome types: T2DM, fasting glucose, glucose tolerance, fasting insulin, insulin secretion and insulin sensitivity. There was moderate evidence to support a role of recreational sun exposure in reducing odds of T2DM incidence. High-level evidence was lacking; evidence presented for other outcomes was of low or insufficient level. This review highlights significant gaps in research pertaining to sun exposure and T2DM-related outcomes. Further research is encouraged as we aim to identify novel preventative strategies for T2DM.