[Heart rate: risk factor, risk marker].

When a correlation between an individual characteristic and the incidence of a disease is detected in epidemiology, this characteristic must satisfy four criteria before it can be considered to be a risk factor it must be strongly associated, universally associated regardless of the population, gender, race, associated independently of already recognized factors, especially age, and a cause-and-effect relationship must be demonstrated by a study influencing this characteristic. The first three criteria define the risk marker. Various examples are given, including that of heart rate and overall and cardiovascular morbidity and mortality.