Sergi Giuseppe, Perissinotto Egle, Pisent Claudia, Buja Alessandra, Maggi Stefania, Coin Alessandra, Grigoletto Francesco, Enzi Giuliano
Department of Medical and Surgical Sciences, Division of Geriatrics, University of Padua, Italy.
J Gerontol A Biol Sci Med Sci. 2005 Jul;60(7):866-71. doi: 10.1093/gerona/60.7.866.
The present study aims at defining a body mass index (BMI) threshold for risk of being underweight in elderly persons on the basis of the BMI distribution in a large Italian population-based sample and on its ability to predict short-term mortality.
At baseline (1992), BMI was obtained for 3110 (1663 males and 1447 females) persons aged 65-84 participating in the Italian Longitudinal Study on Aging (ILSA). BMI and risk factors (age, sex, education, smoking status, disability, and disease status) have been considered for their potential association with 4-year all-cause mortality. Information on vital status at 1995 was obtained for 2551 participants.
The fifth centile of BMI was well approximated by a value of 20 for both sexes. Also in both sexes, at a BMI value of 24 the a posteriori probability of death started to increase, doubling at a value of 22 for men and 20 for women. Crude mortality was 14.6% for men and 9.8% for women. The hazard ratios and confidence intervals (CIs) comparing mortality for each BMI two-unit class to the 26-28 class, after adjusting for confounding variables, showed significantly higher rates only for BMI values below 20 (2.9; 95% CI, 1.2-7.0), although a consistent increase in hazard ratio (1.6; 95% CI, 0.9-3.0) already appeared for the 20-22 BMI group.
Our study confirms that low BMI is an independent predictive factor of short-term mortality in elderly persons. A BMI value of 20 kg/m2 seems to be a reliable threshold for defining underweight elderly persons at high risk. Nevertheless, more careful clinical and nutritional management should also be applied to elderly persons with higher BMI values.
本研究旨在根据意大利一个大型基于人群的样本中的体重指数（BMI）分布及其预测短期死亡率的能力，确定老年人体重过轻风险的BMI阈值。
在基线期（1992年），对参与意大利衰老纵向研究（ILSA）的3110名65 - 84岁的人群（1663名男性和1447名女性）测量了BMI。考虑了BMI及风险因素（年龄、性别、教育程度、吸烟状况、残疾和疾病状况）与4年全因死亡率的潜在关联。获得了2551名参与者1995年的生命状态信息。
两性的BMI第五百分位数均很好地近似于20。同样在两性中，BMI值为24时死亡的后验概率开始增加，男性在BMI值为22、女性在BMI值为20时死亡概率翻倍。男性的粗死亡率为14.6%，女性为9.8%。在调整混杂变量后，将每个BMI两个单位类别与26 - 28类别进行死亡率比较时，危险比和置信区间（CI）显示仅BMI值低于20时死亡率显著更高（2.9；95% CI，1.2 - 7.0），尽管BMI为20 - 22组的危险比已经持续增加（1.6；95% CI，0.9 - 3.0）。
我们的研究证实低BMI是老年人短期死亡率的独立预测因素。BMI值20 kg/m²似乎是定义高危体重过轻老年人的可靠阈值。然而，对于BMI值较高的老年人也应进行更仔细的临床和营养管理。
