Sarcopenic Index Research Articles

Abstract T P115: Sarcopenia and Physical Function in Chronic Stroke

Sarcopenia is defined as an age-related loss in skeletal lean muscle mass and strength and is as a leading contributor to the development of frailty. Stroke survivors have muscle atrophy in paretic (P) vs. nonparetic (P) legs that could contribute to whole body sarcopenia. The purpose of this study was to determine the sarcopenic index in a large population of chronic stroke survivors and compare this group to age, gender, and BMI-matched non-stroke controls. Chronic stroke survivors aged 40 to 84 yrs (n=180, 61% female, 59% African American, BMI: 29±1 kg/m 2 , X±SEM) with mild to moderate gait deficits underwent whole body DXA scans to assess sarcopenic index (appendicular lean mass/ht 2 ). The cutoffs for sarcopenia, by the European Working Group on Sarcopenia, were used and defined as a skeletal muscle index of <7.23 kg/m 2 in men and <5.67 kg/m 2 in women. In the entire group, the prevalence of sarcopenia in stroke survivors (13%) did not differ significantly from that of populations reported previously in the literature. In 61-70 year olds, 87% (n=63) had normal muscle mass and 13% (n=9) were sarcopenic. In 71-80 year olds, 79% (n=30) had normal skeletal muscle index and 21% (n=8) were sarcopenic. Stroke survivors (n=39) were matched with 39 controls on the basis of race, gender, age ±4 years and BMI±2.5 units. After matched pair analysis, 5.1% of the controls had sarcopenia while 12.8% of the control group were sarcopenic (P<0.0001). Sarcopenic index was related to six-minute walking speed (r=0.28, P<0.01). In conclusion, stroke survivors may be at an elevated risk for sarcopenia when considering age, gender, and race to non-stroke individuals which is related to functional mobility in this population.

Relationship between arterial stiffening and skeletal muscle atrophy in hemodialysis patients: a gender comparative study.

Dear Editor, Composition of regional muscle and fat masses are related to arteriosclerotic changes in the general population [1]. This study was aimed to clarify the association of muscle mass in the lower limbs and abdominal fat mass with arteriosclerotic parameters in patients on chronic hemodialysis (HD). We measured abdominal subcutaneous fat mass area (ASFA), abdominal visceral fat mass area (AVFA), and thigh muscle area (TMA) from computed tomography (CT) images and adjusted those by body mass index (BMI) in 124 HD patients (age 61 ± 11 [37–79] years, time on HD 11 ± 10 [0–36] years, male/female = 84/40). Brachial-ankle pulse wave velocity (baPWV) and ankle brachial pressure index (ABI) were also measured together and automatically in CAVI-VaSera VS-1000 (Fukuda Denshi Co, Ltd, Tokyo, Japan) just before HD session. A significant association was found between baPWV and TMA/BMI ratio in male (r = −0.32, p < 0.01). Male patients in the top tertile of baPWV had a significantly lower TMA/BMI ratio when compared with those in the middle tertile and those in the bottom tertile (Table 1). Table 1 Baseline characteristics according to the baPWV tertile TMA/BMI ratio was also correlated with ABI (r = 0.46, p < 0.01) in female patients. There was a significantly lower TMA/BMI ratio in patients with the lowest ABI compared to those with the second and with the highest tertile (Table 2). There was rather an inverse association between AVFA/BMI ratio with baPWV in women (r = −0.38, p < 0.05). Table 2 Baseline characteristics according to the ABI tertile A multiple linear regression analysis adjusted by conventional, nutritional, and anthropometric parameters revealed that TMA/BMI was independently associated with baPWV in male, while with ABI in female (Table 3). In contrast, there was no relationship between AVFA/BMI and ASFA/BMI ratios and arteriosclerotic parameters in men. Table 3 Independent determinants of baPWV and ABI in male and female patients It has been demonstrated that skeletal muscle atrophy is associated with accelerated arteriosclerosis. TMA is inversely associated with baPWV in general subjects [2, 3]. A higher PWV is related to a more profound decline in sarcopenic index in older men [4]. Skeletal muscle mass to visceral fat area ratio is also inversely associated with baPWV [5]. In this study, we showed that TMA/BMI ratio was independently associated with baPWV in male, while with ABI in female HD patients, suggesting a possible association of muscle wasting with arteriosclerotic changes in HD patients. Visceral adiposity is linked to arteriosclerosis. AVFA is positively correlated with baPWV and carotid-femoral PWV in general subjects [2, 6]. Visceral fat level was a predictor of carotid-femoral PWV in peritoneal dialysis patients [7]. A positive relationship between AVFA and baPWV was also observed in diabetic HD patients [8]. In this study, however, AVFA/BMI was rather negatively associated with baPWV in female HD patients. The reasons for this discrepancy are not known, but may be due to a well-preserved nutritional status in female patients with abdominal adiposity. An increased body fat mass volume is paradoxically associated with better outcomes in HD patients [9]. The protective role of accumulated trunk fat on subclinical vascular damage, assessed by carotid-radial PWV, was also observed in the elderly women [10]. In summary, we found that reduced TMA/BMI ratio was independently associated with increased baPWV in male, while with decreased ABI in female patients. The findings support a possible relationship between arteriosclerosis and thigh muscle atrophy even in the dialysis population.

The combination of vitamin D deficiency and mild to moderate chronic kidney disease is associated with low bone mineral density and deteriorated femoral microarchitecture: results from the KNHANES 2008-2011.

Although mild to moderate chronic kidney disease (CKD) and vitamin D deficiency are prevalent in the elderly population worldwide and are associated with sarcopenia, their influence on bone mineral density (BMD) has not been determined. The objective of the study was to determine the combined effects of vitamin D deficiency and CKD on BMD in the elderly population and their relationships with sarcopenia and PTH levels. This was a cross-sectional study with nationally representative samples of 6949 subjects aged 55 years or older from the Korea National Health and Nutrition Examination Surveys conducted between 2008 and 2011. The study population was divided into four groups according to vitamin D and CKD status. The combined association of CKD and vitamin D deficiency [25(OH)D<20 ng/mL] with osteopenia or osteoporosis was assessed, and the status of PTH and the sarcopenic index (appendicular skeletal muscle mass as a percentage of body weight or appendicular skeletal muscle mass per weight) as a measure of sarcopenia were evaluated. BMD in the total hip and femoral neck as well as femoral bone geometry was markedly deteriorated in stage 3 and 4 CKD subjects with vitamin D deficiency compared with other groups. Regardless of gender, these subjects also had higher levels of PTH and increased prevalence of sarcopenia. Multivariable logistic regression analyses demonstrated that CKD subjects with vitamin D deficiency showed a significantly increased risk of osteoporosis or osteopenia [odds ratios 1.49 and 2.06 (1.81 and 2.65) at the femur neck and total hip, respectively, in women (men)], which was mainly associated with elevated levels of PTH and sarcopenia in these groups. The combination of mild to moderate CKD and vitamin D deficiency was significantly associated with low BMD in a geriatric population, linked with hyperparathyroidism and sarcopenia.

Pulse wave velocity is associated with muscle mass decline: Health ABC study

Age-related mechanisms that lead to sarcopenia are not entirely understood. Basal leg blood flow declines with aging by augmented sympathetic vasoconstriction and arterial stiffening, thus a dysfunction in blood vessel dynamics may have an independent role on sarcopenia. We determined whether pulse wave velocity (PWV), marker of arterial stiffness, was associated with skeletal muscle decline. Observational cohort study of older adults(70-79 years) living in Pittsburgh, PA, USA or Memphis, TN, USA. Analyses included 2,405 participants. Correlations among muscle parameters including skeletal muscle density and intermuscular adipose tissue using mid-thigh CT scans were assessed. Linear mixed models tested the association between the change in the sarcopenic index (SI) (assessed by dual energy X-ray absorptiometry) over time and baseline PWV independently of multiple confounders. SI was defined: appendicular lean mass/squared height and calculated at every follow-up (n = 6). Baseline PWV was significantly higher in black women compared to white women (930 ± 431 vs. 843 ± 366; p = 0.0001), while there were no significant differences between black and white men (943 ± 402 vs. 911 ± 375; p = 0.1786). Baseline analyses showed an independent negative association between PWV and muscle parameters after adjusting for confounders in both genders. The PWV-by-race interaction was significant in women and analyses are reported separately by race. Prospective mixed models showed that PWV was an independent determinant of the SI in all men (β = -0.1043; p = 0.0065) and in white women (β = -0.1091; p = 0.0192). In analyses examining the effect of arterial stiffness on limb lean mass over time, PWV correlated with lower leg (β = -0.2196; p = 0.0002)and arm mass (β = -0.0985; p = 0.0011) in all men and lower leg mass(β = -0.1608; p = 0.0027)in white women. In older persons, arterial stiffening is associated with skeletal muscle mass decline differently for race and gender.

A technique to assess body composition and sarcopenia using DXA: application for an obese population

The objective of this study was to explore the accuracy of summing multiple dual-energy X-ray absorptiometry (DXA) scans to estimate whole-body soft tissue measures and the sarcopenic index in female subjects for application to an obese population. Forty-five women who fit within the DXA scanning region (M+/-s.d.; BMI=24.5+/-4.6 kg/m(2)) were scanned four times (one normal whole body (WB) scan, one head/trunk/leg scan allowing trunk delineation (TRK-H-L), one scan with body shifted right (LA) and one left (RA) to allow arm delineation). Fat mass (FM) and appendicular lean mass were determined from the WB scan (aLM(WB)), with the latter determined by summing arm and leg mineral-free lean mass (MFLM). Strong agreement and no differences (M+/-s.d.(DIFF)) were found between FM(WB) and FM(SUM) (-0.12+/-0.38 kg, P=0.37; r=0.999, P<0.001); MFLM(WB) and MFLM(SUM) (0.02+/-0.36 kg, P=0.80; r=0.998, P<0.001); and aLM(WB) and aLM(SUM) (0.12+/-0.32 kg, P=0.63; r=0.994, P<0.001). Summing DXA scans is a valid method for determining the risk for sarcopenic obesity and may aid research regarding obesity and risk for disability.

A Technique To Assess Body Composition And Sarcopenia In Larger Individuals Using DXA

The clinical identification of sarcopenic obesity is not well established; however, an emerging definition normalizes appendicular lean mass (aLM) for height and adiposity. Dual energy X-ray absorptiometry (DXA) is the most commonly used technology to assess risk for sarcopenia but due to width limitations on the scanning bed: 1) delineation of aLM is difficult when assessing obese females due to tissue overlap of the trunk/breast and arm segments; and 2) obese individuals often do not fit in the scanning region which limits accuracy of whole body measures. PURPOSE: To assess the accuracy of summing multiple DXA scans to estimate fat mass (FM), mineral free lean mass (MFLM), aLM and sarcopenic index (SI) in overweight or obese females. METHODS: Overweight or obese females (N = 15, M±SD; BMI = 27.0 ± 2.4 kg/m2) that fit within the DXA scanning region were scanned 4 times [1 normal whole body (WB) scan, 1 head/trunk/leg scan allowing trunk delineation (TRK-H-L), 1 scan with body shifted left (RA) and 1 right (LA) to allow arm delineation]. Whole body FM and MFLM were determined using normal DXA analysis. Appendicular lean mass was determined from the WB scan (aLMWB) summing arms and legs MFLM. Summation of FMSUM, MFLMSUM and aLMSUM from the TRK-H-L, RA and LA partial scans simulated methods needed for measuring larger individuals. SI was calculated adjusting aLM by height and using residuals from regression models predicting aLM from height and fat mass from WB or SUM measures, respectively. RESULTS: Strong agreement and no differences (M±SDDIFF) were found between whole body MFLMWB and MFLMSUM (r = 0.99, p < 0.001; 0.06 ± 0.37 kg, p = 0.55), aLMWB and aLMSUM (r = 0.98, p < 0.001; 0.11 ± 0.60 kg, p = 0.51) and estimates of SI (r = 0.96, p< 0.001; 0.04 ±0.24 kg/m2, p = 0.57). Strong agreement but a small but significant difference was determined for FMWB and FMSUM (r = 1.000, p < 0.001; 0.33 ± 0.37 kg, p = 0.004); however, this did not impact agreement of the residuals from regression models predicting aLM from height and fat mass (r = 0.97, p < 0.001; 0.00 ± 0.61 kg, p = 1.00). CONCLUSION: Summing DXA scans is a valid method to estimate SI and risk for sarcopenic obesity in overweight and obese females. The results of this measurement study will aid research regarding obesity, functional impairment and risk for disability.