The National Cooperative Trial on Multifactorial Prevention of First Heart Attacks and Coronary Mortality in Free-Living, High-Risk, Middle-Aged American Men, Also Known as JUMBO: A Short Story.

The concept of a multiple risk-factor intervention trial (MRFIT) originated in mid-20th century efforts to determine whether modifying the "risk factors" established by cardiovascular disease epidemiology would prevent heart attacks. The term "MRFIT" probably first appeared in the 1968 report to the National Heart Institute from investigators of the National Diet-Heart Feasibility Study. Based on their pilot experience, they recommended a trial of diet alone. Aware, however, that authorities might agree with the rationale but not the implementation of such a massive and risky undertaking, they also proposed an alternative: whether coronary heart disease was preventable at all by simultaneous intervention on several risk factors; that is, a multiple risk-factor intervention trial. After some years agonizing by serial expert committees, the National Heart Institute opted against an explanatory diet trial and for a pragmatic multiple risk-factor intervention, one designed by Institute staff and operated under contract. Meanwhile, an impatient community of investigators met together in the Makarska Conference, outlined a broad cardiovascular disease prevention policy, and submitted their idealized version of a multiple risk-factor trial, called JUMBO. But the National Heart Institute, because of the plan for its own trial, had no funds left for an investigator-initiated proposal. Hence, this background and story of the MRFIT that wasn't.