サルコペニアと骨密度減少

サルコペニアは骨密度減少と関連するという論文を紹介します。

Wu CH, Yang KC, Chang HH, Yen JF, Tsai KS, Huang KC. Sarcopenia is Related to Increased Risk for Low Bone Mineral Density. J Clin Densitom. 2012 Sep 10. pii: S1094-6950(12)00122-9. doi: 10.1016/j.jocd.2012.07.010. [Epub ahead of print]

対象は台湾で在宅生活をしている40-85歳の600人です。骨密度は大腿骨頸部と腰椎をDEXAで、筋肉量はBIAで評価しています。台湾の先行研究で、四肢骨格筋量が男性8.87kg/m2以下、女性6.42kg/m2の場合にサルコペニアと判定しています。

結果ですが、サルコペニアの高齢者では大腿骨頸部と腰椎の骨密度減少を認めることが多かったです。性別、年齢別に検討しても女性ではサルコペニアが独立した危険因子でした。以上より、サルコペニアでは骨密度減少のリスクが高いという結論です。

筋肉量と骨量に関連を認めることは、いくつもの研究で検証されています。リスク因子や介入方法も一部共通しますし、どちらか一方を認めた場合にはもう一方も存在する可能性が高いと考えて、評価、対応すべきかと思います。

Abstract

Lean body mass is positively correlated with bone mineral density (BMD). The association between sarcopenia and BMD is less studied. The aim of the study is to investigate the association between sarcopenia and abnormal BMD. A total of 600 community residents aged 40-85yr (mean=63.63±10.12) from Taipei, Taiwan were included. Abnormal and normal BMD groups were categorized by T-score of femoral neck and lumbar spine (L2-L4) measured by dual-energy X-ray absorptiometry. Skeletal muscle mass (SM) index (SMI) was obtained from SM divided by height squared using bioelectrical impedance analysis (BIA) method. Sarcopenia was defined as SMI less than 8.87kg/m(2) in men and 6.42kg/m(2) in women according to previous Taiwanese sarcopenia study. The association between BMD groups and sarcopenia was examined using binary logistic regression analyses after controlling potential confounders. Subjects with sarcopenia were at higher risk for low BMD (odds ratio (OR) = 1.59, 95% confidence interval (CI)=1.06-2.39 for femoral neck BMD and OR=1.72, 95% CI=1.09-2.72 for lumbar BMD) compared with the nonsarcopenia group. Even in different gender groups with age categorized, sarcopenia was still an important independent factor in female group. The least square (LS) means of BMD of femoral neck and lumbar spine were significantly lower in sarcopenia group. The risk of low BMD increased significantly with sarcopenia.