WHO Collaborative Trial of Multifactorial Prevention

Background/Question:

The goal of this trial, multifactorial risk reduction to prevent coronary heart disease (CHD), would determine the effectiveness of a practical policy most physicians prefer. The trial was designed to estimate the extent to which major risk factors for CHD can be modified, to determine the effect of such changes on CHD incidence and mortality, and to determine the consistency of results among different countries.

Population/Methods:

The trial looked at populations in 80 factories in the United Kingdom, Belgium, Italy, and Poland. Factories were paired based on matches in size, geographical area, and nature of the industry, and the paired factories were randomly assigned to intervention or control. The subjects were men aged 40-59. In the intervention factories the whole group was examined every year for the trial lasting 6 years. Only 10% of the control group was monitored and they had a follow-up every two years. For the intervention factories advice was given for cholesterol-lowering diet for all men; cessation of smoking was targeted to smokers, daily physical exercise was recommended to sedentary workers, weight reduction was encouraged in men 15% or more over overweight, and hypotensive drug therapy was given to men with raised systolic blood pressure.

Results:

Total CHD was reduced by 10.2% in the intervention factories in Belgium, Italy, Poland, and the UK. Fatal CHD was reduced 6.9%, non-fatal myocardial infarction was reduced 14.8%, and total deaths were reduced by 5.3 percent. Comparing countries, intervention factories in Poland had the lowest levels of CHD, both fatal and non-fatal, and lowest total deaths.

Conclusions/Discussion:

This trial was the largest randomized trial of CHD prevention of its time and was unique in its international perspective. Advice to middle-aged men in industry on reducing risk factors was effective to the extent that the advice was accepted. The multifactorial intervention also showed no signs of harmful effects. While the evidence for intervention effect was only moderate, it appeared enough to justify the relatively small costs. (FB)