This study looks at the follow-up of 17 cohorts enrolled between the mid 1980s and 1990s, some of them longitudinally carried out  until December 1998, while others until December 2002. 15 cohorts consisted of persons enrolled from the general population, the 2 other ones from working populations instead. The same methods of data collection and baseline risk factors measurements were used in all cohorts. Equal or comparable questionnaires were used to assess lifestyles (smoking status, physical activity) and personal details (educational level, marital status, occupation). In addition, biological factors (serum total and HDL cholesterol, fasting blood glucose, blood pressure, heart rate, weight, height) were assessed using standardized methods. Personal history of diseases, drug consumption and family history were also comparable.

 

Five cohorts were excluded, three because only fatal events were available, one because the information at baseline on the prevalence of  myocardial infarction and stroke was not available and the last one because the cohort consisted only of people older than 65 years.

 

 Detailed description of cohorts: persons free from previous cardiovascular event

*Events=coronaric and cerebrovasculas major events, N= number of persons examined, F-U=follow-up

 

For each person with or dying from a coronary disease (definite or possible myocardial infarction, coronary death, sudden death, stroke, revascularization surgery) data were collected from various sources (case histories, death certificates, general practitioners’ and specialists’ archives) and the events were validated and classified using the MONICA project methods.

In constructing the risk chart the main focus was on incidence, that is the first major cardiovascular event in people who had not experienced any in the past, belonging to the 40-69 years age range. This age interval was chosen being the largest in terms of number or events identified and common in almost all cohorts. Moreover it was chosen because it is the main focus of attention of many risk charts currently available in which the risk factors analyzed are still relatively unaffected by ageing-related processes.

The risk charts are divided into global absolute categories calculated on the basis of risk factors (age, gender, diabetes, smoking habit, systolic blood pressure and serum cholesterol). The mean follow-up period was 9.4 years for men and 7.9 years for women. A total of 931 first major cardiovascular events were identified and validated.

 

The individual score provides a more precise assessment than that deriving from the charts because it considers continuous values for some risk factors, such as age, serum cholesterol, serum HDL cholesterol and systolic blood pressure; the calculation also includes anti-hypertensive therapy, a long-standing arterial hypertension indicator. Moreover the age range has been extended to 35-69 years. For the individual score, the mean follow-up period was 9.5 years for men and 8 years for women. A total of 971 first major cardiovascular events were identified and validated.


Table 1. Comparison between cardiovascular risk chart and individual score