Plasma triglyceride levels and risk of stroke and carotid atherosclerosis: a systematic review of the epidemiological studies.

Objective: The contribution of lipids to stroke risk remains uncertain; little attention has been paid to the effect of triglyceride levels, an emerging risk factor.

Methods: We performed two independent systematic PubMed literature searches for epidemiological studies that examined the association of triglyceride levels with stroke and carotid intima-media thickness (CIMT).

Results: We identified 31 studies on the relationship between triglyceride levels and stroke risk and 38 on triglyceride levels and CIMT. Although study designs varied widely, nine of the 17 prospective cohort studies (n=140,788) and six of the 14 case-control studies (n=3458 cases, 4089 controls) supported a positive association between elevated triglyceride levels and increased risk of stroke. Combining all available data from prospective studies (n=9) produced a pooled relative risk of main stroke outcome per 1 standard-deviation increase of 1.10 (95% confidence interval, 1.07-1.13) without evidence of heterogeneity. One prospective study and one case-control study reported a negative relationship with haemorrhagic stroke. Of the 38 studies on CIMT (n=43,161), 11 reported a significant correlation between CIMT and triglyceride levels, of which three were unadjusted, and one reported an inverse relationship. All of the three studies with longitudinal analysis, two of which were restricted to women, reported a positive association between baseline triglyceride levels and progression of CIMT.

Conclusions: The weight of evidence in prospective cohort studies favours a positive association between triglyceride levels and stroke, and supports the evaluation of triglyceride-lowering therapy to prevent stroke. However, this review shows the need for additional large prospective studies, especially in stroke subtypes, to establish firmly the independent detrimental effect of triglyceride levels in stroke risk.