Which one of the following intervention studies on coronary aery disease did not observe significient changes in moality or risk factors since the control group was not properly chosen-

MRFIT carried out in USA was aimed at high risk adult males aged 35 to 57 years,over the 7 year follow up period HID moality was reduced by 22%,more in the intervention group but this was not statistically significant. This was because the control group has also changed their habits and lifestyle to a far greater extent than anticipated by the designers of trial.the trial produced no significant changes at all.in moality or risk factors in as much as the control group was not properly chosen. Ref- Park&;s textbook of Preventive and Social Medicine 24th edition.