The Global Absolute Risk (GAR) is an indicator which allows to assess the likelihood of experiencing a major cardiovascular event when the level of some risk factors is known.

With this new approach, individuals at risk are no more identified solely on the strength of each risk factor considered individually, but rather the global assessment of all major risk factors is taken into account. Therefore, GAR is not based on the simple summation of risk factors' values.

 

The use of GAR takes account of the multifactorial origin of cardiovascular disease: the risk level is assessed for each individual on the basis of the principal risk factors considered. Moreover, it offers multiple treatment options to individuals at increased risk: actually, the change in each single risk factor can predictably influence the absolute risk. This allows to respect the possible preferences that a person might come to have, considering that many of the detected risk conditions , such as hypertension and total serum cholesterol, are not accompanied by symptoms.

 

Mathematical functions, derived from longitudinal studies carried out on population groups followed up over time, are used to assess the GAR. The validity of using these risk functions is based on the characteristics of the population generating them and the individuals to whom they are applied.

 

Risk functions include three elements:

• population values of the risk factors (e.g. mean total serum cholesterol and arterial blood pressure values in the population);

• risk coefficients (multiplying factors) which gives each single factor an etiological "weight";

• population's likelihood to survive in the absence of the disease.

All these components vary from one population to another, in particular when a comparison among populations with widely different cultures is made, but also in the case of a comparison between different generational cohorts. Also significant is the size of the cohorts used for deriving the functions: the larger the samples, the greater the number of events that occur and the more stable and reliable the assessments.

These functions have been used to develop two tools for global absolute risk assessment- the cardiovascular risk charts and the individual risk score.

 

The risk charts consist of global absolute risk classes calculated for risk factors categories (age, sex, diabetes, smoking, systolic blood pressure and total serum cholesterol).

 

The individual risk score provides an even more accurate assessment as it takes into account continuous values for some risk factors such as age, total serum cholesterol HDL and systolic blood pressure; anti-hypertensive therapy is also included in the assessment, taking into account that the systolic blood pressure level is influenced by specific drug effects. Anti-hypertensive therapy is also an indicator of longstanding hypertension
 

For this reason, risk chart and individual risk score can give slightly different results.

 

Table 1. Comparison between cardiovascular risk chart and individual score