高血压:腹部脂肪比总脂肪量更危险


  【24drs.com】根据在线发表于9月1日美国心脏学院期刊的一篇文章,腹部脂肪比体脂肪更容易引起高血压。
  
  德州大学西南医学中心的Alvin Chandra医师等人,分析了「达拉斯心脏研究」这项研究的903名参与者的资料,这些研究对象皆完成第二阶段研究且平均被追踪7年。
  
  原始研究世代共有2,716名参与者(年龄18-65岁[中位数40岁],57%是妇女、60%非白人,身体质量指数[BMI]中位数27.5 kg/m2),在2000-2002年完成第一阶段研究;研究者排除原本即有高血压(≧140 mm Hg/≧90 mm Hg)、有服用降血压药物、血压读数偏高的研究对象。
  
  由受训过的研究员为这些研究对象量取多次血压值,进行核磁共振扫描,使用双X光吸光测定法测量下半身体脂肪组成,进行静脉血液样本的生化分析。
  
  纳入的903人中,230人(26%)在中位数7年后发生高血压,这些人年纪偏长、糖尿病盛行率较高、大部份是黑人、研究开始时的血压值比较高,BMI、内脏脂肪组织(VAT)和皮下脂肪组织(SAT)也都比较高(所有的P < .01)。
  
  有发生高血压者,在研究开始时的BMI值高于那些没有发生高血压者(29.9 kg/m2 vs 26.9 kg/m2;P < .0001),不过,两组的平均区间体重增加几乎相同。
  
  研究者使用多变项风险回归模式计算发现,BMI和发生高血压显著相关(P < .0001)。然后,当研究者把VAT和SAT纳入变项时,发现VAT值较高是与发生高血压独立相关的唯一脂肪参数(相对风险[RR]为1.22;95%信心区间[CI]为1.07-1.39;P = .004),研究者发现,年龄、性别、种族之关联性皆无差异。
  
  校正发炎标记之后,前述关联依旧显著。
  
  研究者写道,这些研究结果证明,内脏脂肪在这关联性上比体脂肪更重要。这些结果看来,VAT是BMI和心血管疾病关联的重要关键,VAT和造成发生高血压与胰岛素阻抗有关。
  
  不过,研究者指出,还不清楚特定机转,无法从这个观察研究提出因果关系。
  
  研究者结论指出,这些资料得自多种族、随机组成之世代,结果显示肥胖和发生高血压有关,特别是内脏脂肪,腹膜后脂肪的关联最强。这和越来越多认为与VAT有关而非体脂肪之研究论点一致,各种的心血管风险因素最后促成不良的临床事件。
  
  纽约市Icahn医学院的Lawrence R. Krakoff医师在编辑评论中写道, 腹膜后脂肪作为未来发生高血压的预测因子可能很重要,需要以更大型的流行病学调查、采用简单方便的特定测量方式测得这个特定脂肪,特别是资源有限时。「达拉斯心脏研究」这项研究提供了具有良好特征的前瞻型资料库,其后续分析或许可以有助于揭露这类方法。
  
  资料来源:http://www.24drs.com/professional/list/content.asp?x_idno=7113&x_classno=0&x_chkdelpoint=Y
  

Hypertension: Abdominal Fat May Be More Risky Than Total Fat

By Larry Hand
Medscape Medical News

Fat around the abdomen may be more of a cause of hypertension than overall body fat, according to an article published online September 1 and in the September 9 issue of the Journal of the American College of Cardiology.

Alvin Chandra, MD, from the University of Texas Southwestern Medical Center in Dallas, and colleagues analyzed the records of 903 participants in the Dallas Heart Study who completed the second study phase and were followed for a mean of 7 years.

The researchers drew the study population from an original cohort of 2716 participants (aged 18 to 65 years [median, 40 years old], 57% women, 60% nonwhite, with a median body mass index [BMI] of 27.5 kg/m2) who completed phase 1 of the study during 2000 to 2002. They excluded participants who had baseline hypertension (?140 mm Hg/?90 mm Hg), participants who were taking antihypertensive medications, and participants with elevated blood pressure readings.

Trained professionals took multiple blood pressure measurements, scanned participants with magnetic resonance imaging, used dual X-ray absorptiometry to measure lower body fat composition, and conducted biomarker analysis of venous blood samples.

Of the 903 participants, 230 (26%) had developed hypertension after a median of 7 years. Those participants were older, had higher prevalence of diabetes, were more commonly black, and had higher blood pressure at baseline, as well as higher measures of BMI, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) (all P < .01).

Baseline BMI was higher among the participants who developed hypertension than among those who did not (29.9 kg/m2 vs 26.9 kg/m2; P < .0001). However, the median interval weight increase was almost the same between groups.

Yes, but...

Using multivariable risk regression models, the researchers calculated that BMI was significantly associated with the development of hypertension (P < .0001). Then, when they added in VAT and SAT as variables, they found that higher VAT remained as the only fat parameter independently associated with developing hypertension (relative risk [RR], 1.22; 95% confidence interval [CI], 1.07-1.39; P = .004). They observed no differences in the association among sex, age, or race variables.

The association remained significant after further adjustments for inflammatory biomarkers.

The results suggest "that visceral adipose, rather than total adiposity, is more important in this relationship," the researchers write.

"These results suggest that VAT may be the important link between BMI and cardiovascular disease, and that VAT may be acting in part by promoting the development of hypertension and insulin resistance."

However, the researchers note that the specific mechanism remains unknown, and they cannot draw a causal relationship from an observational study.

They conclude, "These data from a multiethnic, probability-based cohort demonstrate that the association between obesity and the development of hypertension is specifically accounted for by visceral adiposity. The strongest associations were observed with retroperitoneal fat. These data are consistent with a growing body of literature implicating VAT, rather than generalized adiposity, in the aggregation of cardiovascular risk factors that eventually drive adverse clinical events."

In an accompanying editorial comment, Lawrence R. Krakoff, MD, from the Icahn School of Medicine and Mount Sinai in New York City, writes, "The possible importance of retroperitoneal adiposity as a predictor of future hypertension implies the need for simple and practical methods to measure this particular fat depot in larger epidemiological surveys, especially when resources are limited. Further analysis of such a well-characterized prospective database provided by the Dallas Heart Study may unmask such methods."

Four coauthors have reported various relationships with several pharmaceutical companies; none of the other coauthors has reported any relevant financial interests.

J Am Coll Cardiol. 2014;64:997-1004.

    
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