芝加哥 – 據7月17日發表在《美國醫學會雜誌》上的一則研究披露，一則對過去30年來在美國招募並被隨訪的成年人的研究中，這些成年人從成年就開始出現的整體及腹部的肥胖其持續時間的增加與較高的冠狀動脈鈣化率——這是冠心病的一個亞臨床預測因子——相關。
根據文章的背景資料：「亞臨床動脈粥樣硬化——這可通過存在冠狀動脈鈣化（CAC）而確認——會隨著時間的推移而進展，且它可以預測冠心病事件的發生。」整體及腹部肥胖的程度——分別反映為身體質量指數（BMI）及腰圍的增加——是CAC存在及進展的重要的風險因子。
馬裡蘭州貝塞斯達國立心、肺及血液研究所的Jared P. Reis, Ph.D.及其同事開展了一項研究，旨在對整體及腹部肥胖的持續時間是否與CAC的存在及10年性進展有關進行調查。這項研究包括了3275名白人和黑人成年參與者，在1985-1986年研究最開始的時期內他們的年齡為18-30歲；這些人最初沒有整體肥胖（BMI ≥30）或腹部肥胖（男性：腰圍[WC]>40.2英寸；女性：>34.6英寸）；這些人所參加的是涉及多中心的、基於社區的年輕成年人發生冠狀動脈風險(CARDIA)的研究。參與者在隨訪的第15年、20年或25年的檢查時完成了計算機斷層掃描檢查以確認是否存在CAC。通過分別對BMI和WC的反覆測量對整體及腹部肥胖的持續時間進行了計算，其計算的時間是在研究開始後的第2、5、7、10、15、20及25年。
在3275名合格的參與者中，45.7%為黑人，50.6%為女性。在隨訪期間，有40.4%及41.0%的人分別發生了整體及腹部肥胖；對那些發生整體及腹部肥胖的人來說，其平均的肥胖持續時間分別為13.3年和12.2年。
文章的作者寫道：「… 在這一研究中，從成年期開始後在較長持續時間內存在著整體及腹部肥胖與經過中年時的獨立於肥胖程度的CAC及其10年性進展有關。這些發現提示，由於肥胖的流行及其較早的發病時間所致的、在較長的時期內持續地出於過度肥胖狀態將對美國未來的冠狀動脈粥樣硬化負擔及可能的臨床心血管疾病發生率具有重要的意義。」（生物谷Bioon.com）
生物谷推薦英文摘要：
Jama doi:10.1001/jama.2013.7833.
Association Between Duration of Overall and Abdominal Obesity Beginning in Young Adulthood and Coronary Artery Calcification in Middle Age
Jared P. Reis, PhD; Catherine M. Loria, PhD; Cora E. Lewis, MD, MSPH; Tiffany M. Powell-Wiley, MD, MPH; Gina S. Wei, MD, MPH; J. Jeffrey Carr, MD, MS; James G. Terry, MS; Kiang Liu, PhD
Importance Younger individuals are experiencing a greater cumulative exposure to excess adiposity over their lifetime. However, few studies have determined the consequences of long-term obesity.
Objective To examine whether the duration of overall and abdominal obesity was associated with the presence and 10-year progression of coronary artery calcification (CAC), a subclinical predictor of coronary heart disease.
Design, Setting, and Participants Prospective study of 3275 white and black adults aged 18 to 30 years at baseline in 1985-1986 who did not initially have overall obesity (body mass index [BMI] ≥30) or abdominal obesity (men: waist circumference [WC] >102 cm; women: >88 cm) in the multicenter, community-based Coronary Artery Risk Development in Young Adults (CARDIA) study. Participants completed computed tomography scanning for the presence of CAC during the 15-, 20-, or 25-year follow-up examinations. Duration of overall and abdominal obesity was calculated using repeat measurements of BMI and WC, respectively, performed 2, 5, 7, 10, 15, 20, and 25 years after baseline.
Main Outcomes and Measures Presence of CAC was measured by computed tomography at the year 15 (2000-2001), year 20 (2005-2006), or year 25 (2010-2011) follow-up examinations. Ten-year progression of CAC (2000-2001 to 2010-2011) was defined as incident CAC in 2010-2011 or an increase in CAC score of 20 Agatston units or greater.
Results During follow-up, 40.4% and 41.0% developed overall and abdominal obesity, respectively. Rates of CAC per 1000 person-years were higher for those who experienced more than 20 years vs 0 years of overall obesity (16.0 vs 11.0, respectively) and abdominal obesity (16.7 vs 11.0). Approximately 25.2% and 27.7% of those with more than 20 years of overall and abdominal obesity, respectively, experienced progression of CAC vs 20.2% and 19.5% of those with 0 years. After adjustment for BMI or WC and potential confounders, the hazard ratios for CAC for each additional year of overall or abdominal obesity were 1.02 (95% CI, 1.01-1.03) and 1.03 (95% CI, 1.02-1.05), respectively. The adjusted odds ratios for CAC progression were 1.04 (95% CI, 1.01-1.06) and 1.04 (95% CI, 1.01-1.07), respectively. Associations were attenuated but largely persisted following additional adjustment for potential intermediate metabolic factors during follow-up.
Conclusions and Relevance Longer duration of overall and abdominal obesity was associated with subclinical coronary heart disease and its progression through midlife independent of the degree of adiposity. Preventing or at least delaying the onset of obesity in young adulthood may lower the risk of developing atherosclerosis through middle age.