Multiple risk factor interventions for primary prevention of coronary heart disease
Abstract
Background
Primary prevention programmes in many countries attempt to reduce mortality and morbidity due to coronary heart disease (CHD) through risk factor modification. It is widely believed that multiple risk factor intervention using counselling and educational methods is efficacious and cost‐effective and should be expanded. Recent trials examining risk factor changes have cast considerable doubt on the effectiveness of these multiple risk factor interventions.
Objectives
To assess the effects of multiple risk factor intervention for reducing cardiovascular risk factors, total mortality, and mortality from CHD among adults without clinical evidence of established cardiovascular disease.
Search methods
MEDLINE was searched for the original review to 1995. This was updated by searching the Cochrane Central Register of Controlled Trials on The Cochrane Library Issue 3 2001, MEDLINE(2000 to September 2001) and EMBASE (1998 to September 2001).
Selection criteria
Intervention studies using counselling or education to modify more than one cardiovascular risk factor in adults from general populations, occupational groups, or high risk groups. Trials of less than 6 months duration were excluded.
Data collection and analysis
Data were extracted by two reviewers independently. Investigators were contacted to obtain missing information.
Main results
A total of 39 trials were found of which ten reported clinical event data. In the ten trials with clinical event end‐points, the pooled odds ratios for total and CHD mortality were 0.96 (95% confidence intervals (CI) 0.92 to 1.01) and 0.96 (95% CI 0.89 to 1.04) respectively. Net changes in systolic and diastolic blood pressure, and blood cholesterol were (weighted mean differences) ‐3.6 mmHg (95% CI ‐3.9 to ‐3.3 mmHg), ‐2.8 mmHg (95% CI ‐2.9 to ‐2.6 mmHg) and ‐0.07 mMol/l (95% CI ‐0.8 to ‐0.06 mMol/l) respectively. Odds of reduction in smoking prevalence was 20% (95% CI 8% to 31%). Statistical heterogeneity between the studies with respect to mortality and risk factor changes was due to trials focusing on hypertensive participants and those using considerable amounts of drug treatment.
Authors' conclusions
The pooled effects suggest multiple risk factor intervention has no effect on mortality. However, a small, but potentially important, benefit of treatment (about a 10% reduction in CHD mortality) may have been missed. Risk factor changes were relatively modest, were related to the amount of pharmacological treatment used, and in some cases may have been over‐estimated because of regression to the mean effects, lack of intention to treat analyses, habituation to blood pressure measurement, and use of self‐reports of smoking. Interventions using personal or family counselling and education with or without pharmacological treatments appear to be more effective at achieving risk factor reduction and consequent reductions in mortality in high risk hypertensive populations. The evidence suggests that such interventions have limited utility in the general population.
PICOs
Plain language summary
Multiple risk factor interventions for primary prevention of coronary heart disease
In many countries, there is enthusiasm for "Healthy Heart Programmes" that use counseling and educational methods to encourage people to reduce their risks for developing heart disease. These risk factors include high cholesterol, excessive salt intake, high blood pressure, excess weight, a high‐fat diet, smoking, diabetes, and a sedentary lifestyle. This updated review of all relevant studies found that the approach of trying to reduce more than one risk factor ‐ multiple risk factor intervention ‐ advocated by these Programmes do result in small reductions in blood pressure, cholesterol, salt intake, weight loss, etc. Contrary to expectations, these lifestyle changes had little or no impact on the risk of heart attack or death. Possible explanations for this are that the small risk factor changes are not maintained long‐term or are not real but caused by some of the studies being poorly conducted. This review is based on the findings from 39 trials conducted in several countries over the course of three decades. Its authors discourage more research on the topic: "Our methods of attempting behaviour change in the general population are very limited. Different approaches to behaviour change are needed and should be tested empirically before being widely promoted. For example, the availability of foods and better access to recreational and sporting facilities may have a greater impact on dietary and exercise patterns respectively, than health professional advice."
