Low risk-factor profile and long-term cardiovascular and noncardiovascularmortality and life expectancy - Findings for 5 large cohorts of young adult and middle-aged men and women

Context Three major coronary risk factors-serum cholesterol level, blood pr essure, and smoking-increase incidence of coronary heart disease (CHD) and related end points. In previous investigations, risks for low-risk referenc e groups were estimated statistically because samples contained too few suc h people to measure risk. Objective To measure long-term mortality rates for individuals with favorab le levels for all 3 major risk factors, compared with others. Design Two prospective studies, involving 5 cohorts based on age and sex, t hat enrolled persons with a range of risk factors. Low risk was defined as serum cholesterol level less than 5.17 mmol/L (<200 mg/dL), blood pressure less than or equal to 120/80 mm Hg, and no current cigarette smoking. All p ersons with a history of diabetes, myocardial infarction (MI), or, in 3 of 5 cohorts, electrocardiogram (ECG) abnormalities, were excluded. Setting and Participants In 18 US cities, a total of 72 144 men aged 35 thr ough 39 years and 270 671 men aged 40 through 57 years screened (1973-1975) for the Multiple Risk Factor Intervention Trial (MRFIT); in Chicago, a tot al of 10 025 men aged 18 through 39 years, 7490 men aged 40 through 59 year s, and 6229 women aged 40 through 59 years screened (1967-1973) for the Chi cago Heart Association Detection Project in Industry (CHA) (N=366 559). Main Outcome Measures Cause-specific mortality during 16 (MRFIT) and 22 (CH A) years, relative risks (RRs) of death, and estimated greater life expecta ncy, comparing low-risk subcohorts vs others by age strata; Results Low-risk persons comprised only 4.8% to 9.9% of the cohorts. All 5 low-risk groups experienced significantly and markedly lower CHD and cardio vascular disease death rates than those who had elevated cholesterol level, or blood pressure, or smoked. For example, age-adjusted RRs of CHD mortali ty ranged from 0.08 for CHA men aged 18 to 39 years to 0.23 for CHA men age d 40 through 59 years. The age-adjusted relative risks (RRs) for all cardio vascular disease mortality ranged from 0.15 for MRFIT men aged 35 through 3 9 years to 0.28 for CHA men aged 40 through 59 years. The age-adjusted RR f or all-cause mortality rate ranged from 0.42 for CHA men aged 40 through 59 years to 0.60 for CHA women aged 40 through 59 years. Estimated greater li fe expectancy for low-risk groups ranged from 5.8 years for CHA women aged 40 through 59 years to 9.5 years for CHA men aged 18 through 39 years. Conclusions Based on these very large cohort studies, for individuals with favorable levels of cholesterol and blood pressure who do not smoke and do not have diabetes, MI, or ECG abnormalities, long-term mortality is much lo wer and longevity is much greater. A substantial increase in the proportion of the population at lifetime low risk could contribute decisively to endi ng the CMD epidemic.