高齢者の脂肪・筋肉量・筋力と機能低下：メタ解析

高齢者の脂肪・筋肉量・筋力と機能低下の関係のメタ解析を紹介します。

Laura A. Schaap, Annemarie Koster and, Marjolein Visser. Adiposity, Muscle Mass, and Muscle Strength in Relation to Functional Decline in Older Persons. Epidemiol Rev (2012) doi: 10.1093/epirev/mxs006

メタ解析の結果ですが、BMI30以上と筋力低下は、機能低下と有意な関連を認めました。オッズ比はBMI30以上より筋力低下のほうが高いです。一方、筋肉量低下は機能低下と統計学的に有意な関連を認めませんでした（オッズ比1.19、95％信頼区間0.98～1.45ですので無関係とは言えませんが）。

筋肉量低下よりもBMI30以上の肥満や筋力低下のほうが、高齢者への機能低下の影響が大きいとは言えます。サルコペニア肥満対策としても、筋肉量が増加するにこしたことはありませんが、むしろBMI30未満（日本人なら25未満かもしれません）への減量や筋力増強のほうが重要だと思われます。

Abstract

Aging is associated with changes in body composition and muscle strength. This review aimed to determine the relation between different body composition measures and muscle strength measures and functional decline in older men and women. By use of relevant databases (PubMed, Embase, and CINAHL) and keywords in a search from 1976 to April 2012, 50 articles were reviewed that met the inclusion criteria (written in English, a prospective, longitudinal design, involving older persons aged 65 years or more, and at least one of the measures that follow: body mass index (BMI), waist circumference, waist/hip ratio, midarm circumference, fat mass, muscle fat infiltration, muscle mass, or strength as independent variables and a measure of functional decline as outcome measure). Meta-analyses were performed and revealed that BMI ≥30 and low muscle strength were associated with functional decline (pooled odds ratio (OR) = 1.60, 95% confidence interval (CI): 1.43, 1.80, for BMI ≥30 and OR = 1.86, 95% CI: 1.32, 2.64, for muscle strength). Low muscle mass was not significantly associated with functional decline (pooled OR = 1.19, 95% CI: 0.98, 1.45). Future intervention research should focus on positive changes in body composition to prevent onset or worsening of functional decline in old age.