Background: Primary prevention programmes in many countries attempt to reduce mortality and morbidity due to coronary heart disease 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 coronary heart disease among adults without clinical evidence of established cardiovascular disease.
Search strategy: We searched Medline using a standard randomised trial filter. Date of the most recent search was April 1995.
Selection criteria: Intervention studies using counseling 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: Both reviewers, independently extracted data. Investigators were contacted to obtain missing information.
Main results: A total of 18 trials were found of which 10 reported clinical event data. Net changes in systolic and diastolic blood pressure, smoking prevalence, and blood cholesterol were -3.9mmHg (95% CI -4.2,-3.6 mmHg), -2.9 mmHg (95% CI -3.1,-2.7 mmHg), -4.2% (95% CI -4.8, -3.6%), and -0.08mMol/l (95% CI -0.1.-0.06 mMol/l) respectively. In the ten trials with clinical event end-points, the pooled odds ratios for total and coronary heart disease mortality were 0.97 (95% confidence intervals (CI) 0.92-1.02) and 0.97 (95% CI 0.88-1.04) respectively. 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. Only these trials demonstrating significant reductions in mortality.
Reviewer's 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 counseling 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.