Plant sterols and cardiovascular disease: a systematic review and meta-analysis.

The impact of increased serum concentrations of plant sterols on cardiovascular risk is unclear. We conducted a systematic review and meta-analysis aimed to investigate whether there is an association between serum concentrations of two common plant sterols (sitosterol, campesterol) and cardiovascular disease (CVD). We systematically searched the databases MEDLINE, EMBASE, and COCHRANE for studies published between January 1950 and April 2010 that reported either risk ratios (RR) of CVD in relation to serum sterol concentrations (either absolute or expressed as ratios relative to total cholesterol) or serum sterol concentrations in CVD cases and controls separately. We conducted two meta-analyses, one based on RR of CVD contrasting the upper vs. the lower third of the sterol distribution, and another based on standardized mean differences between CVD cases and controls. Summary estimates were derived by fixed and random effects meta-analysis techniques. We identified 17 studies using different designs (four case-control, five nested case-control, three cohort, five cross-sectional) involving 11 182 participants. Eight studies reported RR of CVD and 15 studies reported serum concentrations in CVD cases and controls. Funnel plots showed evidence for publication bias indicating small unpublished studies with non-significant findings. Neither of our meta-analyses suggested any relationship between serum concentrations of sitosterol and campesterol (both absolute concentrations and ratios to cholesterol) and risk of CVD. Our systematic review and meta-analysis did not reveal any evidence of an association between serum concentrations of plant sterols and risk of CVD.

Lipoprotein (a) and risk of cardiovascular disease--a systematic review and meta analysis of prospective studies.

BACKGROUND: Several studies have investigated the role of Lipoprotein (a) as a risk factor for cardiovascular disease (CVD) and have produced controversial results. DATA SOURCES: We conducted a systematic literature review in the databases MEDLINE, EMBASE, and COCHRANE aimed at retrieving prospective studies that investigated the prognostic value of Lipoprotein (a) concentrations on cardiovascular risk and mortality. METHODS: From each study we extracted estimates of risk ratios (RR) with respect to the risk of CVD (endpoints: all coronary heart disease (CHD) events pooled, major coronary events, myocardial infarction, stroke) and all cause mortality. Study specific risk ratios were standardised to contrast the top third with the bottom third of the study specific Lipoprotein (a) distribution. Pooled summary estimates were calculated by using fixed and random effects meta analysis techniques, in total and stratified by study design and study population. RESULTS: For the present meta analysis we selected 67 prospective studies including 181,683 individuals. Synthesising data from 37 studies that reported estimates for the endpoint 'CHD events' resulted in a RR of 1.57 (95% CI: 1.41 to 1.75, p < 0.001). For this endpoint subgroup analyses by design and population showed significant estimates: population based cohort studies: n = 15 studies, RR = 1.48 (95% CI: 1.26 to 1.74, p < 0.001), cohort studies including patients with previous disease: total: n = 11 studies, RR = 1.67 (95% CI: 1.28 to 2.17, p < 0.001), with CHD: n = 6 studies, RR = 2.37 (95% CI: 1.41 to 3.97, p = 0.001), nested case control studies: n = 11 studies, RR = 1.64 (95% CI: 1.47 to 1.83, p < 0.001). We did not find any significant effect on risk of stroke (n = 16 studies, RR = 1.10 (95% CI: 0.97 to 1.25, p = 0.137)) and mortality (n = 9 studies, RR = 1.12 (95% CI: 0.94 to 1.33, p = 0.200)). CONCLUSIONS: This meta analysis of prospective studies shows a clear association between elevated Lipoprotein (a) levels and increased risk of CHD. This effect is substantially higher in individuals with previous CHD. Our systematic review showed no evidence of an effect on stroke and all cause mortality.