Considering technique of assessment and method for normalizing skeletal muscle mass

Association between anorexia of ageing and sarcopenia among Japanese older adults

BACKGROUND

Malnutrition plays an essential role in the mechanism of pathogenesis for sarcopenia. In late life, both food consumption and energy intakes decline. One of key factors for reduced energy intakes is anorexia of ageing. The aim of this study is to examine the association between anorexia of ageing and sarcopenia among community-dwelling elderly Japanese individuals.

METHODS

This uses population-based, cross-sectional cohort study of elderly Japanese individuals. Anorexia of ageing was assessed via a simplified nutritional appetite questionnaire. Handgrip strength and walking speed were tested, and skeletal muscle mass was assessed using a bio-impedance analysis device. Subjects with sarcopenia were defined as those who met the criteria of the Asian Working Group for Sarcopenia. The association between anorexia of ageing and sarcopenia was then analysed via multiple regression analysis.

RESULTS

In total, 9,496 elderly Japanese individuals were evaluated (mean age 74.1 ± 5.4 years; male, 47.0%). The prevalence of anorexia of ageing was 9.8% (n = 927) in the present study. The prevalence of sarcopenia in men was 1.1%, 1.8%, 6.1%, 10.1%, and 21.2% and was 1.6%, 3.3%, 3.6%, 4.8%, and 7.4% in women aged 65-69, 70-74, 75-79, 80-84, and 85 years and older, respectively. The prevalence of anorexia also showed an age-dependent increase in both sexes (P < 0.001, respectively). The prevalence of anorexia in men was 8.3%, 6.3%, 9.8%, 13.6%, and 12.9% and was 7.9%, 9.4%, 10.5%, 17.6%, and 17.1% in women aged 65-69, 70-74, 75-79, 80-84, and 85 years and older, respectively. In multivariable logistic regression model adjusted for the covariates except for albumin, anorexia of ageing was independently associated with sarcopenia (OR: 1.45, 95% CI: 1.07 to 1.95; P = 0.015). This significant association remained even after adjusting for all covariates including nutritional status (OR: 1.42, 95% CI: 1.06 to 1.92, P = 0.020).

CONCLUSIONS

Anorexia of ageing is associated with sarcopenia among Japanese elderly individuals. Further studies are needed to determine whether a causal association exists between anorexia and sarcopenia.

Alterations of body composition patterns in pre-dialysis chronic kidney disease patients

PURPOSE

Body mass index (BMI) might be an inaccurate estimate of detailed body composition because it does not differentiate muscle from fat mass. We sought to understand the effect of kidney function decline on alterations of body composition patterns among pre-dialysis CKD patients.

METHODS

Body composition was measured by multi-frequency bioelectrical impedance analysis (BIA). Low muscle mass was defined as appendicular muscle mass (kg) adjusted to the square of height in meters < 7.0 and 5.7 kg/m² in men and women, respectively. The designation of obesity by percent body fat was ≥ 25% in men and ≥ 30% in women. Alternative definition of obesity by BMI was ≥ 25 kg/m². Visceral fat area cut point was > 100 cm² as indication of abdominal obesity.

RESULTS

Mean age of participants was 61.3 ± 13.8 years (n = 103). The average glomerular filtration rate (GFR) was 34.0 ± 24.2 mL/min/1.73 m². By BIA, the prevalence of low muscle mass was 16.5% and was comparable between both sexes. Obesity by percent body fat was identified in 71.8% of patients and 38.2% had abdominal obesity. Using BMI criteria, the prevalence of obesity was less common (55.3%) and associated with under-identification of obesity by 27.0%. Low muscle mass and obesity by percent body fat were more prevalent in the more advanced stages of CKD. By multivariable regression analysis, a 10 mL/min/1.73 m² decline in GFR was associated with a 0.59 kg reduction of total body muscle mass (p = 0.01), but not fat mass or BMI, after adjusting for confounders.

CONCLUSION

Low muscle mass was prevalent among pre-dialysis CKD patients. BMI commonly classified obese CKD individuals by percent body fat criteria as non-obese. The reduction of muscle mass was associated with GFR decline.