[Why and how to measure cardiovascular risk?].

In cardiovascular medicine, the absolute risk is the observed incidence of events over a defined period of time. The relative risk is the multiplicative factor or risk factor. The cardiovascular global risk is multifactorial but is usually difficult to assess without a predictive model derived from large scale epidemiological studies such as Framingham cohort. The relative weight of discrete risk factors is relatively constant in various populations so that predictive equations can be useful, after adjustment, even when absolute risk levels are different. The main interest to quantify the risk is to help the therapeutic decision by estimating the benefit of an intervention. The cardiovascular risk can be calculated instantly either on the Internet or on palm computer or from colourful tables available from medical press. These calculators can also give some estimate of the therapeutic benefit expressed as the number of patients needed to treat to prevent one event. This mode of expression takes into account both the initial absolute risk and the magnitude of the intervention effect. The therapeutic decision based on global risk (by opposition with single risk factor) is now validated by recent trials such as Heart Prevention Study. This novel approach is somewhat upsetting but is a truly pertinent alternative to our daily practice.