健常者は骨格筋面積と体表面積が相関

健常者では骨格筋面積と体表面積は相関するという論文を紹介します。

Yoshizumi T, Shirabe K, Nakagawara H, Ikegami T, Harimoto N, Toshima T, Yamashita YI, Ikeda T, Soejima Y, Maehara Y. Skeletal muscle area correlates with body surface area in healthy adults. Hepatol Res. 2013 Mar 29. doi: 10.1111/hepr.12119. [Epub ahead of print]

対象は生体肝移植のドナーの健常者で腹部CTを施行した45人です。骨格筋の横断面積はL3尾側レベルで評価しました。体表面積から骨格筋面積を計算する回帰分析を行いました。また回帰式の妥当性を別の30人の健常者で検討しました。

結果ですが、骨格筋面積は男性155.0 cm² (114.0-203.0)、女性111.7 cm² (89.8-139.3)で男女とも体表面積と有意な相関を認めました男性(p < 0.0001, r² = 0.60)、女性(p < 0.0001, r² = 0.78)。

骨格筋面積の回帰式は男性126.9 × BSA（体表面積） - 66.2、女性125.6 × BSA - 81.1でした。回帰式からの骨格筋面積は、実際の骨格筋面積と有意な相関を認めました男性(p = 0.003, r² = 0.64)、女性(p = 0.0001, r² = 0.70)。

サルコペニアは実際の腹部CTでの骨格筋面積とこの回帰式で体表面積から計算した骨格筋面積との違いで定義できるという結論です。健常者のデータですが、サルコペニアの評価の目安になると思います。次はサルコペニア患者でのデータが欲しいですね。

Abstract

BACKGROUND:

Depletion of skeletal muscle mass (sarcopenia) predicts survival in patients with cancer or liver cirrhosis. Recently, many reports have used computed tomography (CT) to measure muscle area to define sarcopenia. However, the definition of sarcopenia using CT has not been fully determined. The aim of this study was to establish formulae to calculate the standard area of skeletal muscle.

METHODS:

Forty-five healthy adults (24 men and 21 women, age range; 21-66) who wished to donate part of their liver for transplantation underwent CT. Cross sectional areas (cm² ) of skeletal muscle was measured at the caudal end of the third lumbar vertebra. Regression analysis was performed to establish formulae to calculate standard area of skeletal muscle. A validation conducted on 30 other healthy adults was performed to check the accuracy of formulae.

RESULTS:

Men had a median skeletal muscle area of 155.0 cm² (114.0-203.0), compared with 111.7 cm² (89.8-139.3)in women (p < 0.001). Furthermore, skeletal muscle area significantly correlated with body surface area (BSA) in men (p < 0.0001, r² = 0.60) and women (p < 0.0001, r² = 0.78). The formulae to calculate skeletal muscle area were 126.9 × BSA - 66.2 in men and 125.6 × BSA - 81.1 in women. The estimated muscle area significantly correlated with actual muscle area in men (p = 0.003, r² = 0.64) and women (p = 0.0001, r² = 0.70).

CONCLUSIONS:

Sarcopenia can be defined by the difference between measured data and calculated data using our new formulae.