身體質量指數與老年人死亡率之相關性－以實證醫學方法探討肥胖矛盾現象

The Relationship between Body Mass Index and All-Cause Mortality in the Elderly: Reviewing Obesity Paradox with an Evidence-Based Approach

謝蔡豪(Tsai-Hao Hsieh) ； 李俊秀(Jason Jiunshiou Lee) ； 陳明正(Ming-Chen Chen) ； 何清幼(Chin-Yu Ho) ； 余文瑞(Wen-Ruey Yu)

《台灣老年醫學暨老年學雜誌》 13卷2期 (2018/05) Pp. 69-86

https://doi.org/10.29461/TGG.201805_13(2).0001

摘要

根據世界衛生組織最新統計，2016年全世界18歲以上成年人體重過重的盛行率為39%，肥胖盛行率則是13%，與四十年前相較達三倍之多。而台灣最新的資料顯示，2015年時18歲以上成年人過重及肥胖盛行率之總和為40.17%，且國人十大死因中有八項與肥胖有關，可知肥胖是當今世界各國以及台灣應積極重視之主要健康議題。雖然過去已有許多文獻證實肥胖及過重是許多慢性病之危險因子，甚至癌症的罹病率也與身體質量指數成正相關，但近年來有文獻指出，特定族群如老年人及某些慢性病患者，其死亡率與身體質量指數呈現反向相關，即所謂「肥胖矛盾」現象。本文藉由實證醫學的方法，將研究族群聚焦於老年人，搜尋證據等級最高的系統性回顧及統合分析，透過詳細評讀文獻來闡明老年人族群中身體質量指數與死亡率之相關性。目前的證據顯示，居住於社區的一般老年族群中，體重過重的死亡風險最低，具有最佳保護效果；至於沒有慢性病與抽菸習慣的健康老年族群中，身體質量指數位於正常值時死亡風險最低，過重族群則沒有統計上的差異。但無論是一般或健康族群，老年肥胖者皆伴隨死亡風險上升達統計意義。

關鍵字

身體質量指數 ； 死亡率 ； 老年人 ； 實證醫學

並列摘要

According to the latest data from the World Health Organization, worldwide obesity has nearly tripled during the past 40 years. In 2016, 39% of adults aged 18 years and over were overweight, and 13% were obese. In the same population in Taiwan, the overweight-obesity prevalence read 40.17% in 2015, and eight of the top ten causes of death among Taiwanese people were related to obesity. All these statistics testify to the gravity of obesity as a major global health issue. Previous literature has identified obesity and overweight as risk factors for a plethora of chronic diseases; even the incidence of cancer has been found to be positively correlated with body mass index. However, recent literature has observed in certain groups, notably the elderly and patients with specific chronic diseases, an inverse relationship between body mass index and mortality rate, thus giving rise to the so-called ＂obesity paradox.＂ In this paper, an evidence-based medicine approach was applied to clarify the relationship between body mass index and mortality in the elderly population by scrutinizing and appraising previous studies with the highest level of evidence, including systematic reviews and meta-analyses. Current evidence shows that in the general community-living elderly population, the mortality risk is at its lowest among those who are overweight, suggesting that overweight may serve as a protection. In the healthy elderly population, defined as never-smokers without chronic diseases, the lowest risk of death occurs when the body mass index is normal, and there is no statistical difference in the overweight group. However, in both the general and healthy elderly populations, obesity appears to be associated with a statistically significant increase in the risk of death.

並列關鍵字

body mass index ； mortality ； elderly ； aged ； evidence-based medicine