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Multiple risk factor intervention trial. Risk factor changes and mortality results. Multiple Risk Factor Intervention
Insights
The Multiple Risk Factor Intervention Trial found no significant difference in coronary heart disease (CHD) mortality between a special intervention group and usual care. Further investigation is needed to understand the complex effects of multifactor interventions on cardiovascular health.
Area of Science:
- Cardiovascular Disease Prevention
- Clinical Trials
- Public Health Interventions
Background:
- Coronary heart disease (CHD) remains a leading cause of mortality.
- Primary prevention trials are crucial for evaluating interventions to reduce cardiovascular risk.
- The Multiple Risk Factor Intervention Trial (MRFIT) aimed to assess a multifactor intervention's impact on high-risk men.
Purpose of the Study:
- To evaluate the effectiveness of a special intervention (SI) program compared to usual care (UC) in reducing CHD mortality.
- To analyze the impact of multifactor risk reduction on cardiovascular outcomes in high-risk men.
- To explore potential explanations for observed mortality rates in the trial.
Main Methods:
- A randomized primary prevention trial involving 12,866 high-risk men aged 35-57 years.
- Participants were assigned to either a special intervention (SI) program or usual care (UC).
- The SI program included hypertension treatment, smoking cessation counseling, and cholesterol-lowering dietary advice.
Main Results:
- Risk factor levels declined in both SI and UC groups, with greater reductions in the SI group.
- CHD mortality was 17.9/1,000 in the SI group and 19.3/1,000 in the UC group (a nonsignificant 7.1% difference).
- Total mortality rates were similar between groups (41.2/1,000 SI vs. 40.4/1,000 UC).
Conclusions:
- The multifactor intervention did not demonstrate a statistically significant reduction in CHD mortality over seven years.
- Possible explanations include insufficient trial duration, lower-than-expected mortality, or offsetting effects of antihypertensive therapy.
- Further research is needed to refine preventive strategies, particularly regarding the balance of different risk factor modifications.
Abstract:
The Multiple Risk Factor Intervention Trial was a randomized primary prevention trial to test the effect of a multifactor intervention program on mortality from coronary heart disease (CHD) in 12,866 high-risk men aged 35 to 57 years. Men were randomly assigned either to a special intervention (SI) program consisting of stepped-care treatment for hypertension, counseling for cigarette smoking, and dietary advice for lowering blood cholesterol levels, or to their usual sources of health care in the community (UC). Over an average follow-up period of seven years, risk factor levels declined in both groups, but to a greater degree for the SI men. Mortality from CHD was 17.9 deaths per 1,000 in the SI group and 19.3 per 1,000 in the UC group, a statistically nonsignificant difference of 7.1% (90% confidence interval, -15% to 25). Total mortality rates were 41.2 per 1,000 (SI) and 40.4 per 1,000 (UC). Three possible explanations for these findings are considered: (1) the overall intervention program, under these circumstances, does not affect CHD mortality; (2) the intervention used does affect CHD mortality, but the benefit was not observed in this trial of seven years' average duration, with lower-than-expected mortality and with considerable risk factor change in the UC group; and (3) measures to reduce cigarette smoking and to lower blood cholesterol levels may have reduced CHD mortality within subgroups of the SI cohort, with a possibly unfavorable response to antihypertensive drug therapy in certain but not all hypertensive subjects. This last possibility was considered most likely, needs further investigation, and lends support to some preventive measures while requiring reassessment of others.