How we present results

Relative Risk

The results of deCODE’s tests are presented as a numerical score representing the patient’s risk of disease relative to the population average risk of 1.0.

Thus, patients with risk results >1.0 are at increased risk relative to the general population, and those who have risk results <1.0 are at decreased risk.

For example, a relative risk of 1.5 is 1.5-fold, or 50% greater risk than, that of the general population. A result of 0.5 corresponds to 0.5-fold, or 50% lower risk than, that of the general population. It is important to note that this risk calculation is based only upon measurement of the markers tested, and does not include other risk factors that may, if integrated with the results of the test, raise or lower an individual’s calculated risk.

To put a particular patient’s results in the context of the range of the test, their relative risk is also presented graphically along the scale from the lowest to highest possible results.

Lifetime Risk

Lifetime risk is calculated by multiplying the average population lifetime risk of the disease (as a percentage) by the patient’s relative risk. The formula is:

Population Lifetime Risk x Relative Risk = Lifetime Risk

For example, if the patient’s relative risk result for a given disease is 1.14, and the average population lifetime risk is 35%, the patient’s lifetime risk is 40.1% (35% x 1.14 = 40.1%).

Without information on other possible risk factors the lifetime risk is based on the presumption that the patient’s background or prior risk is the same as that of the general population. This means that other possible risk factors known to influence lifetime risk have not been taken into account, and may, if then included, increase or decrease the patient’s lifetime risk.

The patient’s lifetime risk is also presented visually, in comparison to the average population risk, as in the scale below:

Population Risk Distribution

Also calculated and presented is a scale showing where the patient’s risk sits within the distribution of risk in the population – that is, the proportion of the population with a lesser, similar or greater risk than the patient.

This content was last reviewed on January 25, 2011.