20多年来美国成人血脂水平逐步改善

根据《美国医学会杂志》10月17日发表的一项针对3次全国调查数据的分析结果，自上世纪80年代以来，美国成人平均血脂水平已得到改善(JAMA 2012;308:1545-54)。

美国国家卫生统计中心(NCHS)的Margaret D. Carrol及其同事称，1988~2012年期间，美国成人总体的平均总胆固醇、非HDL胆固醇和LDL胆固醇水平均有所下降，而平均HDL胆固醇水平升高，大多数种族/族裔和不同性别人群的情况也是如此。

研究者分析了1988~1994年、1999~2002年和2007~2010年全国卫生与营养调查(NHANES)的数据，以了解血脂水平的变化趋势。每次横断面调查的内容包括与受试者面谈有关健康问题，以及对具有全国代表性的数以万计的成人进行体检。

就成人总体而言，上述3个时间段的平均总胆固醇水平分别为206、203和196 g/dl，呈线性下降趋势。除墨西哥裔美国男性外，对男性、女性以及不同种族/族裔亚组的单独分析结果仍然如此。所有成人的LDL胆固醇水平也呈线性下降趋势，分别为128、124和119 mg/dl。男性和女性LDL胆固醇水平均持续下降并最终趋于相同，因此最后一次调查的LDL胆固醇水平不存在性别差异。所有成人HDL胆固醇水平呈线性上升，从50.7 mg/dl提高至52.5 mg/dl，并且不同性别人群的结果亦是如此。如果按照种族/族裔分组分析，白人HDL胆固醇水平有所升高，但黑人或墨西哥裔美国人未见上升。甘油三酯水平变化情况略有不同，上世纪80年代后期(118 mg/dl)至本世纪初(123 mg/dl)呈上升趋势，但到2010年(110 mg/dl)再次下降。上述所有变化趋势在≥50岁的老年人群中均维持不变。

在上述时间段内，服用降脂药物的成人比例也逐渐升高，分别为3.4%、9.3%和15.5%。然而，用药情况并不能解释血脂水平的整体改善，因为未用药成人的血脂水平也有明显改善。

研究者指出，校正年龄后，所有成人、男性、女性以及不同种族/族裔和性别亚组的平均总胆固醇水平均达到了《健康国民2010》所推荐的<200 mg/dl水平。然而，校正年龄后成人平均LDL胆固醇水平为116 mg/dl，仍高于与冠心病低风险相关的<100 mg/dl的理想水平。

研究者推测，血脂水平良好变化趋势可能部分归功于反式脂肪酸消费水平下降和其他健康生活方式改变，不可能是体力活动增加或饱和脂肪酸摄入减少的结果，因为其他研究已表明，在上述研究期间体力活动并未增加，饱和脂肪酸摄入也未减少。

血脂水平实验室分析得到国立心肺血液研究所资助。NHANES由NCHS和CDC完成。研究者报告无利益冲突。

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By: MARY ANN MOON, Cardiology News Digital Network

Mean serum levels of lipids have improved among American adults since the late 1980s, according to an analysis of data from three nationwide surveys, published Oct. 17 in JAMA.

Between 1988 and 2012, mean total cholesterol, non-HDL cholesterol, and LDL cholesterol levels have declined and mean HDL cholesterol levels have risen in adults overall as well as across most racial/ethnic and gender categories, said Margaret D. Carroll of the Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Hyattsville, Md., and her associates.

The investigators examined data from the National Health and Nutrition Examination Surveys (NHANES) for 1988-1994, 1999-2002, and 2007-2010 to track temporal trends in lipid levels. Each cross-sectional survey included health-related interviews and physical examinations of a nationally representative sample of tens of thousands of adults.

In the adult population as a whole, the mean total cholesterol level declined in a linear fashion from 206 mg/dL in 1988-1994 to 203 mg/dL in 1999-2002 and to 196 mg/dL in 2007-2010. This pattern remained the same in separate analyses of men and women and in all racial/ethnic subgroups, except for Mexican American men.

LDL cholesterol also decreased in a linear fashion in all adults, from 128 mg/dL in the first survey to 124 mg/dL in the second and to 119 mg/dL in the final survey. LDL cholesterol levels declined in both men and women and eventually converged, so there was no longer a difference between the sexes in the latest survey.

HDL cholesterol rose in a linear fashion from 50.7 mg/dL to 52.5 mg/dL among all adults, and also rose in separate analyses of both sexes. When the data were broken down by racial/ethnic categories, HDL cholesterol rose in whites of both sexes but not in blacks or Mexican Americans.

Triglycerides showed a slightly different pattern, rising between the late 1980s (118 mg/dL) and the early 2000s (123 mg/dL), but then falling again by 2010 (110 mg/dL).

All of these temporal trends persisted when the analysis was restricted to only the oldest adults, aged 50 and older.

During the study period, the number of adults taking lipid-lowering medications also rose, from 3.4% in 1988-1994 to 9.3% in 1999-2002 and to 15.5% in 2007-2010. However, these medications did not explain the entire improvement in lipid profiles, which also improved markedly in adults who weren’t taking them.

"The Healthy People 2010 guideline of an age-adjusted mean total cholesterol level of 200 mg/dL or less has been achieved in [all] adults, in men, in women, and in all race/ethnicity and sex subgroups. However, the age-adjusted mean LDL cholesterol level in adults of [remains] higher than the optimal range of below 100 mg/dL, [which is] associated with a lower risk of CHD [coronary heart disease]," Ms. Carroll and her colleagues said.

The researchers speculated that the favorable trends in lipid profiles might be attributable in part to a decrease in the consumption of trans-fatty acids and to other healthy lifestyle changes. The changes are unlikely to have resulted from increases in physical activity or decreases in the intake of saturated fat, as other studies have demonstrated that activity has not increased and saturated fat intake has not declined during the study period, they said.

This laboratory analysis of lipids was funded by the National Heart, Lung, and Blood Institute. NHANES is conducted by the National Center for Health Statistics and the Centers for Disease Control and Prevention. No conflicts of interest were reported.