研究：LDL並非總是預(yù)測(cè)中風(fēng)風(fēng)險(xiǎn)最好的指標(biāo)

作者：Caroline Cassels
出處：WebMD醫(yī)學(xué)新聞

　 　December 27, 2007 —一項(xiàng)由加州大學(xué)洛杉磯分校醫(yī)學(xué)中心研究者進(jìn)行的研究顯示，三酸甘油酯最高的個(gè)體，其發(fā)生LAA的機(jī)會(huì)高出2.7倍，而那些非HDL濃度最高的個(gè)體，發(fā)生大血管中風(fēng)風(fēng)險(xiǎn)高出2.5倍；三酸甘油酯與非高密度脂蛋白（HDL）濃度上升，與大血管粥狀硬化（LAA）有關(guān)，暗示低密度脂蛋白（LDL）可能並非總是動(dòng)脈硬化血管風(fēng)險(xiǎn)最好的指標(biāo)。
　　
　　主要研究者Bruce Ovbiagele醫(yī)師在美國(guó)神經(jīng)學(xué)會(huì)的聲明中表示，LDL已經(jīng)是降低中風(fēng)風(fēng)險(xiǎn)的主要標(biāo)的，但是這些結(jié)果顯示其他種類的膽固醇與中風(fēng)風(fēng)險(xiǎn)的關(guān)係更為強(qiáng)烈。
　　
　　這項(xiàng)研究結(jié)果於12月26日發(fā)表於神經(jīng)學(xué)期刊上。
　　
　　【衝突的證據(jù)】
　　根據(jù)作者表示，有關(guān)於循環(huán)中血脂肪對(duì)於中風(fēng)風(fēng)險(xiǎn)的影響，證據(jù)是衝突的，部分早期的研究結(jié)果顯示，中風(fēng)風(fēng)險(xiǎn)與膽固醇濃度上升無關(guān)；然而，他們表示，這項(xiàng)研究一般並未區(qū)分中風(fēng)形式或是血脂肪的形式。
　　
　　近來的研究已經(jīng)證實(shí)血脂肪濃度與缺血性中風(fēng)之間的關(guān)係，但很少有研究檢驗(yàn)血脂肪與跟脂肪代謝最相關(guān)之不同缺血性中風(fēng)亞型之間的關(guān)係。
　　
　　他們寫道，這對(duì)血脂肪濃度在腦血管粥狀硬化形成上可能與冠狀動(dòng)脈血管床不同的證據(jù)上是很重要的。
　　
　　作者指出，目前的美國(guó)國(guó)家治療指引強(qiáng)調(diào)處理LDL膽固醇，大部分是根據(jù)來自心臟相關(guān)研究的證據(jù)；然而，他們表示，有越來越多的證據(jù)顯示，其他來自典型血脂肪的不同血脂肪，可能是比LDL在預(yù)測(cè)血管風(fēng)險(xiǎn)上更好的預(yù)測(cè)因子。
　　
　　【大型研究】
　　在這項(xiàng)研究中，研究者針對(duì)1,049位在2002年9月到2007年4月之間，因?yàn)榧毙灾酗L(fēng)或是短暫性缺血性發(fā)作住進(jìn)一家大學(xué)醫(yī)院醫(yī)學(xué)中心的病患，分析常規(guī)監(jiān)測(cè)血脂肪濃度以及發(fā)生LAA中風(fēng)之間的關(guān)係。
　　
　　所有病患都在入院後的早晨檢驗(yàn)空腹血脂肪濃度，檢驗(yàn)總膽固醇、三酸甘油酯、HDL與LDL；除此之外，也評(píng)估非HDL膽固醇、總膽固醇對(duì)HDL比值、三酸甘油酯對(duì)HDL比值、以及LDL對(duì)HDL比值。
　　
　　根據(jù)他們的臨床癥候群、磁振擴(kuò)散權(quán)重影像數(shù)據(jù)、以及血管、心臟與實(shí)驗(yàn)室數(shù)值的結(jié)果，病患被分為兩群，分別是LAA與非LAA。
　　
　　整體而言，247位LAA組病患，以及802位病患被歸類為非LAA組；非LAA組包括395位心因性栓塞病患、224位小血管疾病（SVD）中風(fēng)病患、89位其他已確認(rèn)病因病患、以及94位原因不明中風(fēng)。
　　
　　【LDL的價(jià)值不應(yīng)該打折扣】
　　研究顯示，LAA與SVD病患的血脂肪濃度並無差異；此外，總膽固醇、三酸甘油酯、LDL、非HDL、三酸甘油酯對(duì)HDL比值，LAA組病患顯然比非LAA與非SVD病患高。
　　
　　在校正年齡、高血壓、糖尿病與是否有吸菸習(xí)慣、身體質(zhì)量指數(shù)、以及在癥狀發(fā)生前是否曾使用statins類藥物後，研究者發(fā)現(xiàn)三酸甘油酯與非HDL與LAA之間有強(qiáng)烈關(guān)係；然而，LAA與LDL之間並無關(guān)聯(lián)。
　　
　　作者指出，其數(shù)據(jù)顯示，其他傳統(tǒng)血清脂肪，例如三酸甘油酯濃度以及常規(guī)血脂肪檢驗(yàn)較少量測(cè)的，例如非HDL膽固醇，可能與有癥狀大血管脊腦部血管動(dòng)脈硬化（相較於其他缺血性中風(fēng)亞型）的關(guān)係更強(qiáng)。
　　
　　根據(jù)這些研究結(jié)果，作者表示，當(dāng)治療有粥狀動(dòng)脈血管硬化中風(fēng)風(fēng)險(xiǎn)或處於風(fēng)險(xiǎn)的病患，臨床醫(yī)師可能需要將更多的注意力放在其他的血脂肪；然而，他們也表示，LDL與病患整體健康的重要性不應(yīng)該打折扣。
　　
　　作者表示無相關(guān)資金上的往來。

LDL Not Always Best Predictor of Stroke Risk, Study Finds

By Caroline Cassels
Medscape Medical News

December 27, 2007 — Elevated levels of serum triglycerides and non–high-density lipoprotein (HDL) have been associated with an increased risk of large artery atherosclerotic (LAA) stroke, suggesting that low-density lipoprotein (LDL) may not always be the best predictor of atherosclerotic vascular risk.

A study by investigators at the University of California, Los Angeles Medical Center shows that individuals with the highest triglycerides are 2.7 times more likely to have LAA, while those with the greatest non-HDL levels had a 2.4-fold increased risk of large artery stroke.

"LDL has been the primary target for reducing the risk of stroke, but these results show other types of cholesterol may be more strongly linked with stroke risk," principal investigator Bruce Ovbiagele, MD, said in a statement from the American Academy of Neurology.

The study is published online December 26 in Neurology.

Conflicting Evidence

According to the authors, there is conflicting evidence with respect to the importance of circulating serum lipids in stroke, with some early studies reporting no association between stroke risk and elevated cholesterol. However, they note, this research generally did not distinguish between stroke subtype or lipid subfractions.

More recent studies have demonstrated an association between serum cholesterol levels and ischemic stroke, but few have examined the relationship between serum lipids and subtype of ischemic stroke most directly linked to lipid metabolism.

"This may be important in light of evidence that the effect of plasma lipids on atherogenesis in the cerebral vascular bed may be distinct from that in the coronary vascular bed," they write.

The authors point out that current national US guidelines, which emphasize the management of LDL cholesterol, are largely based on evidence from the cardiac literature.

However, they note, "there is mounting evidence that other serum lipid indices derived from the classic lipid profile may be better predictors of vascular risk than LDL."

Large Study

For the study, the investigators analyzed measures of routinely ordered serum lipid panels and the occurrence of LAA stroke in 1049 patients admitted with acute stroke or transient ischemic attack from September 2002 through April 2007 to a single university center.

All patients had fasting lipid panels drawn early in the morning the day after hospital admission. Total cholesterol, triglycerides, HDL, and LDL were assessed. In addition, non-HDL cholesterol, total cholesterol-to-HDL ratio, triglyceride-to-HDL ratio, and LDL-to-HDL ratio were also assessed.

Based on their clinical syndromes, diffusion-weighted imaging data, and the results of vascular, cardiologic, and laboratory studies, patients were divided into 2 groups — LAA and non-LAA.

Overall, 247 patients were in the LAA group and 802 classified in the non-LAA group. The non-LAA group consisted of 395 patients with cardioembolism, 224 with small vessel disease (SVD) stroke, 89 patients with other determined etiology, and 94 patients with cryptogenic stroke.

LDL Should Not Be Discounted

The study showed lipid levels were similar between LAA and SVD patients. Furthermore, total cholesterol, triglycerides, LDL, non-HDL, and triglyceride/HDL ratio were significantly higher in LAA than in non-LAA, non-SVD patients.

After adjusting for age, hypertension, diabetes, smoking habits, body-mass index, and the prior use of statins before onset of symptoms, the investigators found a strong association between triglycerides and non-HDL and LAA. However, there was no association between LAA and LDL.

"Our data indicate that other traditional serum lipid measures such as the triglyceride level, as well as less commonly assessed indices derived from the routinely ordered serum lipid panel such as non-HDL cholesterol, may be more strongly associated with symptomatic large artery cervicocephalic atherosclerosis (vs all other ischemic stroke subtypes) than LDL level," the authors write.

In light of these findings, the authors suggest when treating patients with or at risk for atherosclerotic stroke, clinicians may want to consider focusing additional attention on other aspects of the lipid panel. However, they note, LDL and its role in patients' overall health should not be discounted.

The authors report no conflicts of interest.

Neurology. Published online December 26, 2007.