サルコペニア肥満と変形性膝関節症

サルコペニア肥満では変形性膝関節症が多いという横断研究です。

Lee S, Kim TN, Kim SH. Sarcopenic obesity is more closely associated with knee osteoarthritis than is nonsarcopenic obesity: A cross-sectional study. Arthritis Rheum. 2012 Dec;64(12):3947-54. doi: 10.1002/art.37696.

サルコペニアはDEXAで筋肉量が若年の2SD以下の場合としています。サルコペニアでない肥満のカットオフ値は、BMI27.5以上としています。

結果ですが、サルコペニア肥満では、サルコペニアでない肥満の場合より、同じ体重であっても変形性膝関節症の有病割合が高かったです。サルコペニアで肥満でない場合には、変形性膝関節症のリスクではありませんでした。

サルコペニア、変形性膝関節症ともロコモティブシンドロームの原因の1つですが、サルコペニア肥満の場合には変形性膝関節症を合併しやすくなるため、よりロコモの可能性も高くなるのだと思います。ロコモでは低栄養も問題ですが、サルコペニア肥満も問題ですね。

Abstract

OBJECTIVE:

Sarcopenic obesity is a body composition category in which obesity is accompanied by low skeletal muscle mass, offsetting the increase in body weight caused by increased adipose tissue. The purpose of this study was to analyze the association between knee osteoarthritis (OA) and 4 different categories of body composition: normal, sarcopenic nonobesity, nonsarcopenic obesity, and sarcopenic obesity.

METHODS:

This was a cross-sectional study using the data from 2,893 participants in the Fifth Korean National Health and Nutrition Examination Survey. Radiographic knee OA was defined as a Kellgren/Lawrence grade of ≥2. Appendicular skeletal muscle mass (ASM) and whole-body fat mass were measured using dual x-ray absorptiometry. Sarcopenia was defined as a skeletal muscle mass index (ASM/body weight [%]) below -2SD of the value in sex-matched young reference groups. Nonsarcopenic obesity was defined as a body mass index (BMI) ≥27.5 kg/m(2) .

RESULTS:

The prevalence of each body composition category was as follows: 83.5% normal, 4.3% sarcopenic nonobesity, 9.2% nonsarcopenic obesity, and 3.0% sarcopenic obesity. Compared with nonsarcopenic obesity participants, participants with sarcopenic obesity were significantly older, had lower ASM, higher whole-body fat mass, and higher waist circumference. However, there was no significant difference in body weight or BMI. In multivariate analysis, sarcopenic obesity was more closely associated with radiographic knee OA (OR 3.51 [95% confidence interval (95% CI) 2.15-5.75]) than was nonsarcopenic obesity (OR 2.38 [95% CI 1.80-3.15]). Sarcopenic nonobesity showed no significant association with knee OA.

CONCLUSION:

Sarcopenic obesity was more closely associated with knee OA than was nonsarcopenic obesity, although both groups had equivalent body weight. This finding supports the importance of the systemic metabolic effect of obesity in knee OA.