没有“良性”肥胖这回事

《内科学年鉴》(Annals of Internal Medicine) 12月2日在线发表的一份研究报告显示，“代谢健康”的超重和肥胖患者短期内发生全因死亡和心血管事件的风险可能与体重正常者相同，但体重偏高仍会使其长期风险增加。

加拿大多伦多西奈领先糖尿病中心的Caroline K. Kramer博士及其同事说，多项研究报告称发现了一个肥胖患者的亚组，他们虽然多脂但代谢特征正常，研究者将这种情况称为“良性肥胖”或“代谢健康肥胖”。据称这类患者的全因死亡和心血管风险与体重正常者相同甚至更低。但是，这些研究的随访期较短，因此其结论多少有些令人质疑。

Kramer博士及其同事对8项评估受试者代谢状态和体重的研究的结果进行了合并分析；这些研究的随访期为3年至30年。共涉及患者61,386例，死亡或心血管事件3,988例。

代谢状态分为健康或不健康，取决于血脂、糖耐量、血压、胰岛素抵抗、腰围等因素。

初始分析显示，代谢健康的超重和肥胖患者的结局与代谢健康的体重正常者类似。但仅对至少随访了10年的研究进行分析时发现，代谢健康的肥胖组患者死亡和心血管风险增加，危险比为1.24。

此外，无论体重如何，代谢不健康的所有患者出现死亡和心血管事件的风险均增加。事实上，代谢不健康的体重正常者出现死亡或心血管事件的风险与代谢不健康的超重和肥胖患者相同。研究者指出，这提示代谢不健康的体重正常者应该成为临床实践中需特别关注的一个患者人群。

研究者总结道，8项观察性研究的meta分析结果显示，超重会使患者10年后的死亡和心血管风险增加，即便是在“代谢健康”的肥胖患者中。研究者写道：“我们的结果不支持‘良性肥胖’这一概念，‘健康’类型的肥胖是不存在的。” (Ann. Intern. Med. 2013 Dec. 2;159 [doi=10.7326/0003-4819-159-11-201312030-00002])。

Kramer博士及其同事还指出：“我们的研究结果强调了全面评估的必要性，不仅要评估体重指数(BMI)，还要评估代谢因子以预测未来的患病率和死亡率。”研究结果还表明，随访持续时间是“评估低危人群未来事件的关键要素。”

研究者认为，对于那些被错误地视为“良性肥胖”或“代谢健康肥胖”的患者，超重与亚临床代谢和血管功能障碍相关，随着时间的推移这最终会导致死亡和心血管事件增加。

Kramer博士声明无相关利益冲突。有一名作者声明接受了默克和诺和诺德公司提供的研究经费和其他费用。

随刊述评：揭开“健康肥胖”的假象

James O. Hill博士和Holly R. Wyatt博士说，这项meta分析提供了强有力的证据证明“健康肥胖”其实是一种假象。也驳倒了这样的观点：由于社会无法负担每一位肥胖者的治疗，所以只应该优先治疗那些存在代谢风险的肥胖者。

他们说：“没有哪种肥胖是健康的，接受这一观点是我们前进的重要一步，有助于我们确定如何才能最好地利用我们的资源和意愿来制定并实施战胜肥胖流行的策略。”

Hill博士和Wyatt博士来自美国科罗拉多大学Anschutz健康与保健中心。Hill博士声明与麦当劳、可口可乐公司以及其他公司之间存在经济利益关系。Wyatt博士声明与Atkins、Retrofit以及其他公司之间存在利益关系。上述文字摘自Kramer博士研究报告的随刊评论(Ann. Intern. Med. 2013 Dec. 2;159:789-90)。

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By: MARY ANN MOON, Cardiology News Digital Network

"Metabolically healthy" overweight and obese patients may carry the same short-term risk as normal-weight patients for all-cause mortality and cardiovascular events, but their weight puts them at increased risk over the long term, according to a report published online Dec. 2 in Annals of Internal Medicine.

Several studies have reported finding a subgroup of obese individuals who have normal metabolic features despite their high adiposity, and the researchers have called this condition "benign obesity" or "metabolically healthy obesity." Such patients reportedly have the same or even lower all-cause mortality and CV risk as normal-weight patients. But those studies tended to have short follow-up, making their conclusions somewhat questionable, said Dr. Caroline K. Kramer of the Leadership Sinai Centre for Diabetes, Toronto, and her associates.

The findings from their meta-analysis of eight observational studies indicate that excess weight confers increased risk after 10 years, even in "metabolically healthy" obese patients. "Our results do not support this concept of ‘benign obesity’ and demonstrate that there is no ‘healthy’ pattern of obesity," the researchers wrote (Ann. Intern. Med. 2013 Dec. 2;159 [doi=10.7326/0003-4819-159-11-201312030-00002]).

Dr. Kramer and her colleagues pooled the results of eight studies that examined participants’ metabolic status as well as weight, which had follow-up intervals ranging from 3 years to 30 years. That yielded a sample of 61,386 patients, with 3,988 deaths or CV events.

Metabolic status was categorized as either healthy or unhealthy, depending on factors such as lipid profile, glucose tolerance, blood pressure, insulin resistance, and waist circumference.

In an initial analysis, overweight and obese patients who were metabolically healthy had similar outcomes as metabolically healthy normal-weight patients. But when the analysis was confined to studies with at least 10 years of follow-up, the metabolically healthy obese group had increased mortality and CV risk, with a risk ratio of 1.24.

In addition, all patients who were metabolically unhealthy were at increased risk for death and CV events, regardless of their weight. In fact, normal-weight patients who were metabolically unhealthy carried the same risk of death or CV events as did overweight and obese patients who were metabolically unhealthy. That indicates that normal-weight patients who are metabolically unhealthy are a patient population that merits particular attention in clinical practice, the investigators said.

"Our findings highlight the need for comprehensive evaluation of not only BMI [body mass index] but also metabolic factors for the prediction of future morbidity and mortality," Dr. Kramer and her associates said.

The findings also show that duration of follow-up "is a critical element in evaluating low-risk populations for future events, the researchers noted.

The investigators proposed that in patients erroneously deemed to have "benign obesity" or "metabolically healthy obesity," excess weight is associated with subclinical metabolic and vascular dysfunction that ultimately leads to increased mortality and CV events over time.

Dr. Kramer had no relevant conflicts of interest. One of her coauthors reported receiving grants and fees from Merck and Novo Nordisk.

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Exposing the ‘healthy obesity’ myth

The meta-analysis provides strong evidence that "healthy obesity" is a myth. And it refutes the idea that, because society cannot afford to treat everyone with obesity, it should prioritize treatment only for those at metabolic risk, said James O. Hill, Ph.D., and Dr. Holly R. Wyatt.

"Accepting that no level of obesity is healthy is an important step toward deciding how best to use our resources and our political will to develop and implement strategies to combat the obesity epidemic," they said.

Dr. Hill and Dr. Wyatt are at the Anschutz Health and Wellness Center at the University of Colorado, Aurora. Dr. Hill reported financial ties to McDonald’s, the Coca-Cola Company, and other companies. Dr. Wyatt reported ties to Atkins, Retrofit, and other companies. These remarks were taken from their editorial accompanying Dr. Kramer’s report (Ann. Intern. Med. 2013 Dec. 2;159:789-90).