閉経後女性のサルコペニア肥満のカットオフ値

ブラジルにおける閉経後女性のサルコペニア肥満のカットオフ値提案に関する論文を紹介します。

Oliveira RJ, Bottaro M, Júnior JT, Farinatti PT, Bezerra LA, Lima RM. Identification of sarcopenic obesity in postmenopausal women: a cutoff proposal. Braz J Med Biol Res. 2011 Nov;44(11):1171-6.

下記のHPで全文見ることができると思います。
http://www.scielo.br/pdf/bjmbr/v44n11/884.pdf

DEXAを使用して閉経後女性258人と若年女性349人の身体組成（除脂肪量、脂肪量）を評価しています。除脂肪量の脂肪量および身長に対する割合が、若年の2SD以下の場合をサルコペニア肥満のカットオフ値としています。

閉経後女性の平均年齢は66.8歳、平均身長153cm、平均体重65.7kg、平均BMI28です。体脂肪率は39.6％、除脂肪量は37.7kg、四肢筋肉量は14.5kg、四肢筋肉量指数（四肢筋肉量÷身長÷身長）は6.2が平均です。

カットオフ値は残差（residual）-3.4で、19.8％がサルコペニア肥満と判断されました（このあたりの統計手法を理解できていません、すみません）。このカットオフ値を用いると、サルコペニア肥満患者では、筋力や持久力が有意に低下していました。

サルコペニア肥満では、肥満の診断基準は大きな問題がありませんが、サルコペニアの診断基準が問題となります。筋肉の絶対量で判断するのか、筋肉量の脂肪量、身長、体重に対する割合で判断するのか、筋力や身体機能（歩行速度）も考慮するのかが、今後の課題といえます。

Abstract
Sarcopenic obesity is the combination of reduced fat-free mass (FFM) and increased fat mass (FM) with advancing age but there is lack of clear criteria for its identification. The purposes of the present investigation were: 1) to determine the prevalence of postmenopausal women with reduced FFM relative to their FM and height, and 2) to examine whether there are associations between the proposed classification and health-related variables. A total of 607 women were included in this cross-sectional study and were separated into two subsets: 258 older women with a mean age of 66.8 ± 5.6 years and 349 young women aged 18-40 years (mean age, 29.0 ± 7.5 years). All volunteers underwent body composition assessment by dual-energy X-ray absorptiometry. The FFM index relative to FM and height was calculated and the cutoff value corresponded to two standard deviations below the mean of the young reference group. To examine the clinical significance of the classification, all older participants underwent measurements of quadriceps strength and cardiorespiratory fitness. Values were compared between those who were classified as low FFM or not, using an independent samples t-test and correlations were examined. The cutoff corresponded to a residual of -3.4 and generated a sarcopenic obesity prevalence of 19.8% that was associated with reduced muscle strength and aerobic fitness among the older participants. Also, the index correlated significantly with the health-related fitness variables. The results demonstrated reduced functional capacity for those below the proposed cutoff and suggested applicability of the approach as a definition for sarcopenic obesity.