经济危机有益健康？！

1991~1995年古巴严重经济危机期间发生了食品、燃料极度短缺，该国国民的平均体重降低了4~5 kg。日前《英国医学杂志》在线发表的一项研究显示，在此期间，古巴人的糖尿病和心血管病死亡率也出现了大幅下降(BMJ 2013;346:f1515[doi:10.1136/bmj.f1515])。

主要作者、西班牙Alcala 大学社会与心血管流行病学研究组的Manuel Franco博士指出，随着经济危机消除，古巴人的体重回升，糖尿病发病率和死亡率也相应反弹，但心血管死亡率却维持在较低水平。“古巴经验显示，在一个相对较短的时期内总体人群的轻度体重下降，即可对糖尿病、心血管病总负担和全因死亡率产生深远影响。上述数据生动展示了遏制全球肥胖流行的潜在健康益处。”

Franco博士及其同事利用每年横断面健康调查数据，分析了1980~2010年期间古巴西恩富戈斯省居民的体重变化情况。每年的调查均纳入1,000~2,000名年龄≥15岁受访者，由受访者报告其体力活动水平。研究者还从其他调查中获得了关于能量摄入、吸烟、糖尿病和死亡率的人群数据。

在经济危机期间，古巴食物供应不足，机动车辆交通实际上陷入停滞状态。于是，古巴人步行和骑自行车增多，同时热量摄入减少，因而整个人群处于能量负平衡状态。古巴的城市农业取得了令人鼓舞的成就，使更多人得以获得新鲜农产品。公共卫生行动的重点是建立社区菜园和改善营养，并将超过100万辆自行车分发给市民。

1996年，古巴经济开始复苏，并在2000年之前持续增长。多个健康问题也体现出这种随时间而改变的趋势。

人均每日能量摄入量在20世纪90年代中期跌至最低点，到2005年左右回升至经济危机前水平，此后继续增加。相应的，总体人群的体重指数(BMI)在20世纪90年代中期降低了5.5 kg/m²，2005年左右回升至经济危机前水平，近年来显著增加。

在经济危机末期的1995年，人群中体重正常者所占比例达到了最高的56%。至2010年时，这一比例降至42%，而超重或肥胖者所占比例由33%的低点增至53%。

与此相似，经济危机前，糖尿病发病率稳定在大约1.5~1.8/1,000人，经济危机期间降至1.2/1,000人，在低位徘徊数年后，从2000年开始急剧上升，2002年时超过了经济危机前水平，达到2.2/1,000人，至2009年更是进一步增至2.4/1,000人。换言之，糖尿病总发病率在经济危机期间降低了53%，之后又反弹了140%。

糖尿病死亡率显示出了相似的变化模式：在经济危机期间降低了50%，截至2002年时已反弹了49%，2010年时又回到了经济危机前水平。

冠心病死亡率也是如此：先在经济危机期间显著降低了34%，之后反弹至危机前水平。卒中死亡率也遵循同一规律。不过癌症死亡率并未如此。

不过研究者也指出，迄今为止，针对预防性生活方式干预策略效果的研究“既未显示出对心血管死亡率或糖尿病控制和死亡率的有益效应，也未能使风险降低到具有足够说服力的水平。”

这项研究的局限性在于，它无法排除经济危机期间古巴人吸烟减少所带来的影响。

研究者无利益冲突披露。

随刊述评：该研究展示出对整个人群的益处

Walter C. Willett博士在随刊述评中指出，Franco博士及其同事的发现“为‘减少超重和肥胖可给整个人群带来显著益处’的说法提供了有力证据”。“实现这一目标或许是本世纪公共卫生领域乃至整个社会所面临的主要挑战。”(BMJ 2013;346:f1777 [doi:10.1136/bmj.f1777])

要想做到这一点，可能的策略包括：在教育方面做出努力，优化建筑环境以促进体育锻炼，调整食品系统，限制对儿童宣传不健康饮食，以及利用税收等经济杠杆。除了这些措施之外，“医生们也能通过监测患者体重和指导患者避免超重而贡献出自己的力量。近期证据提示，以临床为基础的减重计划是有效的。”

Willett博士是哈佛公共卫生学院营养学系主任。他报告称无相关利益冲突。

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By: MARY ANN MOON, Cardiology News Digital Network

A severe economic crisis in Cuba in 1991-1995 that caused extreme food and fuel shortages was associated with a population-wide loss of 4-5 kg in weight, accompanied by dramatic reductions in diabetes and cardiovascular mortality, according to a report published online April 9 in the BMJ.

As the crisis resolved, the population’s rebound in body weight was associated with a rise in diabetes incidence and mortality, and a leveling off of the decline in CV mortality, said Dr. Manuel Franco of the social and cardiovascular epidemiology research group, University of Alcala, Madrid, and his associates.

"The Cuban experience shows that within a relatively short period, modest weight loss in the whole population can have a profound effect on the overall burden of diabetes," as well as CV disease and all-cause mortality." These data are a notable illustration of the potential health benefits of reversing the global obesity epidemic," the investigators said.

Dr. Franco and his colleagues studied population-wide changes in body weight over time using data from several annual cross-sectional health surveys performed in the province of Cienfuegos, Cuba, from 1980 to 2010. Each year’s surveys involved 1,000-2,000 respondents aged 15 years and older who self-reported their physical activity levels. Population data regarding energy intake, smoking, diabetes, and mortality were derived from other surveys.

During the economic crisis, food was scarce and motorized transportation came to a virtual standstill in Cuba. The consequent increase in walking and biking, together with reduced caloric intake, "put the entire population in a negative energy balance," they said.

Urban agriculture was encouraged, giving more people access to fresh produce. Public health campaigns emphasized community gardening and improved nutrition, and more than 1 million bicycles were distributed to the population.

The Cuban economy began recovering in 1996 and has shown sustained growth since 2000.

Several health issues reflected this time trend.

The average daily intake of energy per capita decreased to a nadir in the mid-1990s, then rebounded to pre-crisis levels in the mid-2000s and has since increased further. There was a concomitant population-wide decrease of 5.5 kg across all categories of body mass index in the mid-1990s, a rebound to pre-crisis levels in the mid-2000s, and a striking rise in more recent years.

The proportion of the population who were at normal weight was highest, at 56%, in 1995, the final year of the economic crisis. This decreased to 42% in 2010. Concomitantly, the proportion of the population who were overweight or obese rose from a low of 33% to a high of 53%.

Similarly, the incidence of diabetes was stable at roughly 1.5-1.8/1,000 population before the economic crisis. It fell to 1.2/1,000 during the crisis and remained low for a few years, then sharply increased beginning in the year 2000. The incidence of diabetes exceeded pre-crisis levels, at 2.2/1,000, in 2002, and rose again to 2.4/1,000 in 2009.

Thus, the overall incidence of diabetes decreased by 53% during and immediately after the economic crisis, then rose by 140% during the subsequent economic recovery, the researchers wrote (BMJ 2013;346:f1515[doi:10.1136/bmj.f1515]).

Diabetes mortality followed a similar pattern, decreasing by 50% during and immediately after the crisis, rebounding by 49% by 2002, and returning to pre-crisis levels by 2010.

Trends in mortality from coronary heart disease also followed suit, falling markedly by 34% during and immediately following the economic crisis, then rebounding to pre-crisis levels. Stroke mortality also followed this pattern. Cancer mortality did not.

"Our study presents the first observation of a population-wide event of this magnitude and its subsequent effects on public health," said Dr. Franco, who is also in the department of epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, and his associates.

In contrast, studies of the effectiveness of preventive lifestyle strategies "have either not produced a beneficial effect on cardiovascular mortality or diabetes control and mortality, or have been unsuccessful in reducing risk to a sufficient degree to warrant a conclusion," the investigators said.

This study was limited in that it could not account for the effects of a concomitant decrease in both the prevalence and the amount of cigarette smoking in Cuba during the economic crisis, they added.

No financial conflicts of interest were reported.

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Study illustrates population-wide benefits

The findings of Franco and colleagues "add powerful evidence that a reduction in overweight and obesity would have major population-wide benefits," said Dr. Walter C. Willett.

"To achieve this is perhaps the major public health and societal challenge of the century," he noted.

Potential strategies to achieve this include "educational efforts, redesign of built environments to promote physical activity, changes in food systems, restrictions on aggressive promotion of unhealthy drinks and foods to children, and economic strategies such as taxation." Independent of these measures, "physicians can help by monitoring weight and counseling patients who gain weight before they become overweight. Recent evidence indicates that clinic based weight loss programs can be effective. Physicians can help promote healthy social norms by visibly engaging in healthy behaviors."

Dr. Willett is professor and chair of the department of nutrition at Harvard School of Public Health, Boston. He reported no financial conflicts of interest. These remarks were taken from his editorial comment accompanying Dr. Franco’s report (BMJ 2013;346:f1777 [doi:10.1136/bmj.f1777]).