BMIより上腕周囲長と下腿周囲長が予後予測に有用

BMIよりも上腕周囲長（MAC）と下腿周囲長（CC）のほうが施設入所中の高齢者の健康状態と死亡リスクの予測に優れているという論文を紹介します。

Alan Chung-Hong Tsaia, Ming-Chen Lai, and Tsui-Lan Changa: Mid-arm and calf circumferences (MAC and CC) are better than body mass index (BMI) in predicting health status and mortality risk in institutionalized elderly Taiwanese. Archives of Gerontology and Geriatrics doi:10.1016/j.archger.2011.05.015

施設入所中の台湾の高齢者１６０人を対象に、BMI、MAC、CC、MNA、ADLを評価して、１年間フォローしています。平均値はBMI２１．５、MAC２４．８、CC２８．３でした。

CC、MAC、BMIの順番で、１２ヶ月後の栄養状態と健康状態を予測できるという結果でした。死亡リスクに関してはMACが最も正確に予測でき、BMIが最も不正確でした。

BMIは栄養指標の１つと考えていますが、施設では検査（BIAやDEXAなど）の使用は困難ですから、CCやMACも同時に評価したほうがよいかもしれません。

ただ、今回の研究では調査されていませんが、私は意図しない体重減少が、最も１２ヶ月後の栄養状態、健康状態、死亡リスクを正確に予測できるのではないか考えています。

Abstract
The study was to compare the ability of BMI, MAC and CC in predicting nutritional status, functional ability and follow-up mortality risk of older adults. The study purposively recruited 160 of 320 residents of a nursing home in Central Taiwan to serve as subjects. Residents who were ≥65 years old, cognitively normal, without acute conditions and non-hospitalized were qualified to participate. All subjects signed an informed consent. Each was interviewed with a structured questionnaire for sociodemographic, lifestyle and health-related information; evaluated with the Mini Nutritional Assessment (MNA) and the Activities of Daily Living (ADL) scales; measured for weight, height, MAC and CC; and assayed for nutrition-related biochemical values. Results showed that CC was the best, followed by MAC and then BMI in predicting the nutritional status and health conditions. CC and MAC were also more effective than BMI in predicting 12-month follow-up mortality. Overall, CC is the most capable in predicting nutritional status, functional activity and general health conditions; MAC is the most capable in predicting 12-month follow-up mortality risk whereas BMI is the weakest in all functions. These results should have practical implication in geriatric health measurements.