体重、虚弱、障害の関係

体重、虚弱、障害の関係を調査した論文を紹介します。

Bowen ME. The relationship between body weight, frailty, and the disablement process. J Gerontol B Psychol Sci Soc Sci. 2012 Sep;67(5):618-26. doi: 10.1093/geronb/gbs067.

後ろ向きコホート研究で、50歳以上の地域在住の方（平均年齢64歳、非虚弱3218人、前虚弱6894人、虚弱1379人）を対象に、その後8年間で機能障害を認めたかどうかを調べています。

結果ですが、正常体重（BMI18.6-24.9）で非虚弱の方と比較して、肥満（BMI30以上）で前虚弱の方は機能障害が16％少なかったです。また、虚弱で過栄養（BMI25-29.9）の場合は10％、虚弱で肥満の場合は36％、機能障害が少ない結果でした。

また、虚弱で肥満の場合はADL低下も27％少なかったです。以上より、前虚弱と虚弱の場合には、体重が多いほうが機能障害の割合の減少に有用かもしれないという結論です。

前虚弱と虚弱でもObesity Paradoxを認めるのかもしれません。ただ、虚弱でない場合には正常体重が望ましいわけですし、日本人ではObesity Paradoxを認めない可能性もあります。それでも前虚弱と虚弱になったら、減量はしないほうがよいのかもしれません…。

Abstract

OBJECTIVES:

To prospectively examine the relationship between body weight, frailty, and the disablement process.

METHOD:

Longitudinal data from the Health and Retirement Study (1998-2006) were used to examine the relationship between being underweight, overweight, or obese (compared with normal weight) and the onset and progression of functional limitations and disabilities in instrumental activities of daily living (IADL) and activities of daily living (ADL) among a nationally representative sample of community-dwelling older adults (aged 50 and older) with characteristics of frailty (n= 11,491). Nonlinear multilevel models additionally adjusted for demographic characteristics and intra-individual changes in body weight, socioeconomic status, health behaviors, and health conditions over the course of 8 years.

RESULTS:

Compared with their nonfrail normal weight counterparts, prefrail obese respondents have a 16% (p ≤ 0.001) reduction in the expected functional limitations rate and frail overweight and obese respondents have a 10% (p ≤ 0.01) and 36% (p ≤ 0.001) reduction in the expected functional limitations rate, respectively. In addition, frail obese respondents have a 27% (p ≤ 0.05) reduction in the expected ADL disability rate.

DISCUSSION:

This study's findings suggest that underweight, overweight, and obese status differentially affect the risk for functional limitations and disabilities in IADL and ADL. Among prefrail and frail adults, some excess body weight in later life may be beneficial, reducing the rate of functional limitations and disability.