a disease-control method based on the observation that proportional reduction in risk for given absolute reductions in risk factors is independent of the level of the risk factor: for instance reducing systolic blood pressure by 10 mmHg produces the same percentage reduction in risk of heart attack or stroke at all levels of pretreatment blood pressure. The benefits of reducing such risk factors depend mainly on the absolute risk of disease, not on the pretreatment levels of specific risk factors. This contrasts with risk factor management based on a threshold for each factor (e.g., blood pressure, cholesterol level) above which a treatable abnormality (e.g., hypertension, hyperlipidemia) is deemed to be present. Absolute risks are strongly influenced by unmodifiable risk factors such as age, sex, and prior history of disease and are expressed as percentage probabilities of disease occurrence within specified time horizons, usually 5 or 10 years. Under the absolute risk approach, the decision to treat elevated blood pressure or serum cholesterol depends on the estimated overall level of risk rather than the level of any single risk factor. Implementing an absolute risk approach may imply substantial changes to public health strategies and to the circumstances in which allocation of resources for preventive medication is justifiable.