High blood triglycerides identified as independent risk factor for stroke
Most health experts say that high levels of triglycerides and LDL cholesterol are risk factors for heart disease. But the risk may not end there. A recent study published in Circulation: Journal of the American Heart Association is the first to identify high blood triglyceride levels as a strong independent risk factor for stroke.
About the study
Researchers from the Bezafibrate Infarction Prevention (BIP) Study Group in Israel followed 11,177 patients between the ages of 40 and 74 who had coronary heart disease (CHD) but no history of stroke or transient ischemic attack (TIA)—"mini-strokes" that last a few minutes and resolve completely within 24 hours. At the beginning of the study, the patients underwent a complete physical exam that included blood tests for cholesterol and triglycerides. In addition, information about medical history, medication use and risk factors for stroke were obtained.
After six to eight years of follow-up, researchers collected the medical records and/or death certificates of these patients. They looked at how many of the patients had strokes or TIAs. They then compared these results to the patients' blood triglyceride levels to determine whether people with higher blood triglyceride levels had more strokes or TIAs than people with lower levels. Because there are so many related risk factors for CHD and stroke, rigorous data analysis was needed to isolate the effect of high triglycerides from the effects of other risk factors such as total cholesterol and LDL cholesterol.
Of the 11,177 patients, 941 developed a cerebrovascular disease (CVD), of whom 487 had a stroke or TIA. Analysis of the data showed that patients with triglyceride levels of 200 mg/dL (2.3 mmol/L) or higher were nearly 30% more likely to have an ischemic stroke or TIA than those with triglyceride levels below 200. An additional finding was that people with lower HDL cholesterol were more likely to have an ischemic stroke or TIA than people with higher HDL levels. This suggests that higher HDL levels would be protective against stroke, much as they seem to protect against CHD.
In order to isolate the effect of high triglycerides on stroke or TIA, researchers had to tease out a number of other risk factors. These included high total cholesterol, high LDL cholesterol, low HDL cholesterol, increasing age, diabetes mellitus, smoking, hypertension, prior heart attack, and being male. Even after accounting for these factors, the results still suggested that high triglycerides are a risk factor for stroke and TIA independent of these other risk factors.
There are several limitations in the design of this study that may have affected the results.
First, the researchers were looking at triglyceride measurements that had been taken six to eight years in the past. It's possible that during the six to eight years between the time of the lipid tests and the time the medical records and death certificates were analyzed, some patients' triglyceride levels changed. In addition, the people in this study all had CHD, a condition that tends to occur at a younger age than stroke and shares many of the same risk factors. If this factor affected the results, it may well have caused the study to underestimate the strength of high triglycerides as a risk factor.
How does this affect you?
We know from previous research that high levels of LDL cholesterol and triglycerides are risk factors for heart disease. And we know that low levels of HDL cholesterol are also a risk factor for heart disease. The results of this study suggest that the same is true for stroke and TIA.
Based on these results, you have yet another reason to work on keeping your LDL cholesterol and triglycerides down and your HDL cholesterol levels up. General recommendations for lowering LDL and triglycerides include:
- A diet that contains less than 30% of calories from fat and less than 10% of calories from saturated fat
- Drinking alcoholic beverages only in moderation
- Living an active lifestyle
- Maintaining a healthy weight
- Lipid-lowering medications, if prescribed by your physician
Because these risk factors can be modified by diet and lifestyle, it is important to see your health care provider regularly for check-ups. He or she can monitor your cholesterol and triglyceride levels and suggest ways to lower your risk of stroke.
Tanne D, et al. Blood lipids and first-ever ischemic stroke/transient ischemic attack in the Bezafibrate Infarction Prevention (BIP) Registry: High triglycerides constitute an independent risk factor.
Circulation . Dec 11, 2001;104: 2892-2897.
Last reviewed Dec 17, 2001 by ]]>Richard Glickman-Simon, MD]]>
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