Role of body mass index in the prediction of all cause mortality in over 62,000 men and women. The Italian RIFLE Pooling Project. Risk Factor and Life Expectancy.

STUDY OBJECTIVE: To evaluate the relation of body mass index (BMI) to short-term mortality in a large Italian population sample. DESIGN: Within the Italian RIFLE pooling project, BMI was measured in 47 population samples made of 32,741 men and 30,305 women ages 20-69 years (young 20-44, mature 45-69). Data on mortality were collected for the next six years. MAIN OUTCOME MEASURES: Age adjusted death rates in quintile classes of BMI and Cox proportional hazards models with six year all causes mortality as end point, BMI as covariate and age, smoking, systolic blood pressure as possible confounders were computed. Multivariate analysis was tested in all subjects and after the exclusion of smokers, early (first two years) deaths, and both categories. RESULTS: The univariate analysis failed to demonstrate in all cases a U or inverse J shaped relation. The Cox coefficients for the linear and quadratic terms of BMI proved significant for both young and mature women. The minimum of the curve was located at 27.0 (24.0, 30.0, 95% confidence limits, CL) and 31.8 (25.5, 38.2, 95% CL) units of BMI, for young and mature women respectively. Similar findings were obtained even when exclusion were performed. No relation was found for young men while for mature adult men only the model for all subjects retained significant curvilinear relation (minimum 29.3; 22.4, 36.2, 95% CL). CONCLUSION: These uncommon high values of BMI carrying the minimum risk of death seems to be in contrast with weight guidelines. A confirmation of these findings in other population groups might induce the consideration of changes in the suggested healthy values of BMI.

Serum triglycerides in the prediction of coronary artery disease (an Italian experience).

An occupational group living in Rome and composed of 3,007 men aged 46 to 65 years who were free from previous major coronary events was screened for a number of coronary risk factors and then followed up for 10 years. In all, 107 coronary deaths occurred in 10 years. There was a positive relation between coronary death rate and increasing levels of triglycerides, but the difference between the extreme quintile classes was not any more significant after adjustment for cholesterol levels. A cross-classification involving low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglyceride levels showed a higher coronary artery disease (CAD) mortality in subjects with a higher LDL cholesterol/HDL cholesterol ratio and higher triglycerides. However, the excess risk in this subgroup was largely explained by the mean levels of total cholesterol. The multivariate proportional-hazards Cox model with coronary deaths as the end point, and age and triglycerides as predictors, produced a significant coefficient for triglycerides that became nonsignificant when other lipids alone or in combination (total, HDL and LDL cholesterol and some of their ratio) were fed into the model as further covariates. It is concluded that there is no evidence of an independent role of triglycerides in the prediction of coronary deaths.

[Treatment of smoking in myocardial infarction survivors]. / Il trattamento dell'abitudine al fumo nei soggetti sopravvissuti ad un infarto miocardico.

Cigarette smoking is a well known primary risk factor of myocardial infarction. Many studies have shown that it is also a secondary risk factor able to predict the short and medium term occurrence of reinfarction and mortality. A number of observational studies suggest that patients who survive a first myocardial infarction have a halved risk of dying or of recurrence as compared to those who continue to smoke. Presently it is estimated that about 80% of smokers surviving a myocardial infarction quit smoking in short time. The intervention against smoking habits must be primarily conducted using advice and psychological means by the physician, with the help of other health personnel and of the social support of the family and friends.

Trends in coronary risk factors in Italy. Responsible Investigators of the RF2, OB43 and MICOL Research Groups.

Three large-scale epidemiological surveys covering some major coronary risk factors were conducted in Italy in population samples of men and women aged 30-59 years. The first survey was carried out in 1978-1979 (RF2 study; nine samples in eight regions; 2561 men and 2912 women); the second in 1983-1984 (OB43 study; nine samples in the same eight regions; 2267 men and 2398 women); and the third one in 1985-1987 (MICOL study; 18 samples in 10 regions; 14,411 men and 12,611 women). Time trends in mean age standardized risk factors levels showed slight but systematic decreases in blood pressure, cigarette smoking (only in men), and body mass index (only in women); whereas no substantial changes were observed in serum cholesterol levels. The combined multiple coronary risk estimated by a model produced in a previous study, showed a decline between 1978-1979 and 1983-1984 of 5.5% in men and 13.4% in women. These changes were compared with the official coronary death rates between 1984 and 1987 in the whole country and in the regions where the samples were located. The expected/observed ratio computed in different ways ranged from 0.54 to 0.88 for men and was over 1 for women. Changes in the levels of major risk factors and changes in coronary mortality seem biologically coherent at least in men.

The prediction of coronary heart disease in different population samples.

Two population samples of men aged 46-65 years were examined for the measurement of some cardiovascular risk factors and followed up for 6.5 years. The two groups were: 1) 3338 men belonging to occupational groups examined in Rome (ROG) in 1979-81 and 2) 1543 men belonging to two demographic samples of rural areas located in northern and central Italy (IRA) examined in 1965. In men free from previous myocardial infarction the rate of fatal coronary events was 18.0 in the ROG group and 17.5 per 1000 in the IRA group. Five established risk factors (age, systolic blood pressure, serum cholesterol, cigarette consumption and body mass index) were used in a multivariate model for predicting coronary deaths. The coefficients of the multiple logistic function were similar in the two populations group. However, when the IRA coefficients were applied to the ROG factors, they predicted 43 events instead of 58 (under-estimation of 26%; p < 0.05), whereas the ROG coefficients predicted 31 events instead of 26 in the IRA sample (over-estimation of 19%; p = n.s.). A model which included the pool of the two populations and a dummy-variable for the identification of each of them, suggested that being a member of the ROG group is accompained, everything else being equal, by an extra risk of 26%.

Multivariate prediction of coronary deaths in a 10 year follow-up of an Italian occupational male cohort.

3395 men aged 46-65 belonging to occupational groups in Rome were examined in 1980 for the measurement of a number of potential coronary risk factors and of other personal characteristics. They represented the 76.5% of the enrolled roster. In 2853 men free from previous major coronary events and with all the measurements available, 98 died from CHD in the next 10 years. The multivariate analysis performed by the Cox model showed the significant predictive role of age, systolic blood pressure, non-HDL cholesterol, blood glucose and heart rate. The relative risk (for a distance of 2 standard deviations from the mean) was of 2.3, 2.1, 1.4, 1.7 and 1.4 respectively. Smoking habits, body mass index, xanthelasma, leisure physical activity, serum triglycerides, uric acid and a stress score did not contribute to the prediction of coronary deaths. HDL cholesterol produced a negative but not significant coefficient. As compared to the previously available Italian risk functions the role of non-HDL cholesterol and of blood glucose represents the most remarkable contribution.