[Total risk for cardiovascular disease. At what point is medical prophylactic medication useful?].
Despite the epidemiological importance of coronary artery disease: cardiovascular events are rare from the individual viewpoint. There is considerable uncertainty when to start medical treatment. A given risk factor modification results in a relative risk reduction independent of the global risk. Therefore the global risk determines the absolute benefit of a preventive measure. The global risk can be estimated using different scoring systems. Using the global risk and the expected relative risk reduction, the number needed to treat (NNT) to avoid one event or cardiac death can be calculated. The NNT is a measure for the usefulness of a preventive intervention. A NNT of <200 appears acceptable for primary prevention. This can be achieved with pharmacological preventive strategies if the global risk of 10 years is > or =20%. As age is one of the most important risk predictors the need for treatment at comparable risk factor constellations is age dependent. Risk stratification with estimation of the NNT is therefore important for the decision to treat or not to treat.