The multiple risk factor intervention trial (MRFIT). VII. A comparison of risk factor changes between the two study groups

Risk factor changes over 4 years for MRFIT Special Intervention (SI) participants are compared with risk factor changes made by Usual Care (UC) participants. Differences between the two study groups are compared with original design assumptions. After 4 years of follow-up, serum cholesterol differences averaged 50% of what was predicted; diastolic blood pressure differences between the two study groups averaged 67% of that predicted; cigarette smoking reductions in the Special Intervention group relative to the Usual Care group have exceeded what was predicted each year based on reported histories. When serum thiocyanate is used to verify reported cessation the SI-UC difference is reduced but still averages greater than the reductions predicted in the third and fourth years of follow-up.