Interventions for primary prevention of cardiovascular disease: umbrella review of systematic reviews

Background

Cardiovascular diseases are the leading cause of death globally. The aim of this overview of systematic reviews was to compare the effectiveness of different pharmacological and non-pharmacological interventions for the primary prevention of cardiovascular disease.

Methods

A structured search of the Cochrane Database of Systematic Reviews, MEDLINE, EMBASE and the Database of Abstracts of Reviews of Effects archive was conducted to find systematic reviews that reported the effect of various pharmacological and non-pharmacological interventions for the primary prevention of cardiovascular disease from inception to March 2021. References of included studies were also checked. The included systematic reviews' methodological quality was assessed using the Assessment of Multiple Systematic Reviews 2 instrument (range, 0-16). The outcomes of each included review's meta-analysis were extracted and described narratively.

Results

This study analysed 95 systematic reviews, including 41 on non-pharmacological interventions and 54 on pharmacological interventions for cardiovascular health. The majority of the reviews focused on lipid-lowering interventions (n = 25) and antiplatelet medications (n = 21), followed by nutritional supplements, dietary interventions, physical activity, health promotion and other interventions. Only 1 of the 10 reviews addressing cardiovascular mortality showed a potential benefit, while the others found no effect. Antiplatelets were found to have a beneficial effect on all-cause mortality in 2 out of 12 meta-analyses and on major cardiovascular disease events in 8 out of 17 reviews. Lipid-lowering interventions showed beneficial effects on cardiovascular disease mortality, all-cause mortality and major cardiovascular disease events in varying numbers of the reviews. Glucose-lowering medications demonstrated significant benefits for major cardiovascular events, coronary heart disease events and mortality. However, the combination of dietary interventions, physical activities, nutritional supplements and polypills showed little or no significant benefit for major cardiovascular outcomes or mortality.

Future work and limitations

More research is needed to determine whether the effect of treatment varies depending on population characteristics. The findings of this review should be interpreted with caution because the majority of studies of non-pharmacological interventions compare primary prevention with usual care, which may include recommended pharmacological treatment in higher-risk patients (e.g. statins and/or antihypertensive medications, etc.). In addition, randomised controlled trial evidence may be better suited to the study of pharmacological interventions than dietary and lifestyle interventions.

Conclusions

This umbrella review captured the variability in different interventions on randomised controlled trial evidence on interventions for primary prevention of cardiovascular disease and identified areas that may benefit from further research. Specifically, this review focused on randomised controlled trial evidence on interventions for primary prevention of cardiovascular disease. Researchers may use these findings as a resource to direct new intervention studies and network meta-analyses to compare the efficacy of various interventions based on these findings.

Funding

This article presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme as award number 17/148/05.

Coenzyme Q10 supplementation - In ageing and disease

Coenzyme Q₁₀ (CoQ₁₀) is an essential component of the mitochondrial electron transport chain. It is also an antioxidant in cellular membranes and lipoproteins. All cells produce CoQ₁₀ by a specialized cytoplasmatic-mitochondrial pathway. CoQ₁₀ deficiency can result from genetic failure or ageing. Some drugs including statins, widely used by inter alia elderly, may inhibit endogenous CoQ₁₀ synthesis. There are also chronic diseases with lower levels of CoQ₁₀ in tissues and organs. High doses of CoQ₁₀ may increase both circulating and intracellular levels, but there are conflicting results regarding bioavailability. Here, we review the current knowledge of CoQ₁₀ biosynthesis and primary and acquired CoQ₁₀ deficiency, and results from clinical trials based on CoQ₁₀ supplementation. There are indications that supplementation positively affects mitochondrial deficiency syndrome and some of the symptoms of ageing. Cardiovascular disease and inflammation appear to be alleviated by the antioxidant effect of CoQ₁₀. There is a need for further studies and well-designed clinical trials, with CoQ₁₀ in a formulation of proven bioavailability, involving a greater number of participants undergoing longer treatments in order to assess the benefits of CoQ₁₀ treatment in neurodegenerative disorders, as well as in metabolic syndrome and its complications.

Vitamin C supplementation for the primary prevention of cardiovascular disease

BACKGROUND

Vitamin C is an essential micronutrient and powerful antioxidant. Observational studies have shown an inverse relationship between vitamin C intake and major cardiovascular events and cardiovascular disease (CVD) risk factors. Results from clinical trials are less consistent.

OBJECTIVES

To determine the effectiveness of vitamin C supplementation as a single supplement for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases on 11 May 2016: the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library; MEDLINE (Ovid); Embase Classic and Embase (Ovid); Web of Science Core Collection (Thomson Reuters); Database of Abstracts of Reviews of Effects (DARE); Health Technology Assessment Database and Health Economics Evaluations Database in the Cochrane Library. We searched trial registers on 13 April 2016 and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials of vitamin C supplementation as a single nutrient supplement lasting at least three months and involving healthy adults or adults at moderate and high risk of CVD were included. The comparison group was no intervention or placebo. The outcomes of interest were CVD clinical events and CVD risk factors.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, abstracted the data and assessed the risk of bias.

MAIN RESULTS

We included eight trials with 15,445 participants randomised. The largest trial with 14,641 participants provided data on our primary outcomes. Seven trials reported on CVD risk factors. Three of the eight trials were regarded at high risk of bias for either reporting or attrition bias, most of the 'Risk of bias' domains for the remaining trials were judged as unclear, with the exception of the largest trial where most domains were judged to be at low risk of bias.The composite endpoint, major CVD events was not different between the vitamin C and placebo group (hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.89 to 1.10; 1 study; 14,641 participants; low-quality evidence) in the Physicians Health Study II over eight years of follow-up. Similar results were obtained for all-cause mortality HR 1.07, 95% CI 0.97 to 1.18; 1 study; 14,641 participants; very low-quality evidence, total myocardial infarction (MI) (fatal and non-fatal) HR 1.04 (95% CI 0.87 to 1.24); 1 study; 14,641 participants; low-quality evidence, total stroke (fatal and non-fatal) HR 0.89 (95% CI 0.74 to 1.07); 1 study; 14,641 participants; low-quality evidence, CVD mortality HR 1.02 (95% 0.85 to 1.22); 1 study; 14,641 participants; very low-quality evidence, self-reported coronary artery bypass grafting (CABG)/percutaneous transluminal coronary angioplasty (PTCA) HR 0.96 (95% CI 0.86 to 1.07); 1 study; 14,641 participants; low-quality evidence, self-reported angina HR 0.93 (95% CI 0.84 to 1.03); 1 study; 14,641 participants; low-quality evidence.The evidence for the majority of primary outcomes was downgraded (low quality) because of indirectness and imprecision. For all-cause mortality and CVD mortality, the evidence was very low because more factors affected the directness of the evidence and because of inconsistency.Four studies did not state sources of funding, two studies declared non-commercial funding and two studies declared both commercial and non-commercial funding.

AUTHORS' CONCLUSIONS

Currently, there is no evidence to suggest that vitamin C supplementation reduces the risk of CVD in healthy participants and those at increased risk of CVD, but current evidence is limited to one trial of middle-aged and older male physicians from the USA. There is limited low- and very low-quality evidence currently on the effect of vitamin C supplementation and risk of CVD risk factors.