All of life involves risk. Whether it’s crossing the street, taking a new job, or falling in love.
When it comes to living a long, healthy life, there’s always going to be some amount of risk. Avoiding it entirely isn’t realistic.
The good news is… You can be proactive about your health today to reduce your risks in the future.
In our disease reports, we use the word “risk” a lot. Risk is a way of measuring your chance of getting a disease. There are two main kinds of risk — absolute and relative risk — and each has different implications for your health (1).
01
Absolute risk
Let’s start with absolute risk, which measures how many people who share lifestyle and genetic factors will develop a particular disease. For example, a researcher could measure how many smokers with a specific genetic disposition develop lung cancer. This is the smoker’s absolute risk for lung cancer.
We always aim to calculate your absolute risk in your disease reports. To do so, we combine your DNA with other relevant information, like your BMI, sex at birth, age, and others.
The more we understand the genetics of a specific disease — like migraines, asthma, and type 2 diabetes — the more your absolute risk estimate will be shaped by your DNA. The less scientists currently know about the genetics underlying a specific disease — like ovarian, lung, or gastric cancer — the more your risk estimate is shaped by lifestyle and the environment.
Absolute risk can change over time. For example, BMI greatly impacts your risk for type 2 diabetes. If your BMI goes up or down, your absolute risk for type 2 diabetes could also change.
Age is another key variable. For example, it’s the main non-genetic factor we use when calculating someone’s risk for age-related macular degeneration, a common eye condition. Young people tend to have extremely low absolute risk for the condition.
Hence, in cases like this, absolute risk isn’t very informative. We’ll instead provide only a relative genetic risk.
02
Relative risk
Relative risk generally compares people who share certain risk factors to those without. For example, a researcher could see how many smokers get lung cancer compared to non-smokers in order to determine a smoker’s increased risk for the disease.
In your reports, we compare your relative risk to other people who share the same genetic ancestry as you.
It’s important to note that having a higher relative genetic risk doesn’t always mean that you also have a high absolute risk for a disease.
03
Words matter
We use “developing,” “getting,” or “having” to describe risk in our reports.
These words describe the three most common ways of measuring risk: lifetime risk, incidence, and prevalence (2,3).
Lifetime risk
Lifetime risk measures a person's chance of experiencing a certain disease at some point in their life. If lifetime risk is the best measure of your risk for a certain disease, we’ll tell you your risk of developing that disease in your report.
Incidence
Incidence is the number of people who are newly diagnosed with a specific disease over a specific period of time. If incidence is the best measure of your risk for a disease, we’ll tell you your risk of getting that disease in your report. Incidence rates can fluctuate over time.
Prevalence
Prevalence measures the total number of people with a disease at a particular time. If prevalence is the best measure of your risk for a certain disease, we’ll tell you your risk of having that disease in your report. Prevalence rates can also change over time.
Understanding the different kinds of risk is important to your health, and understanding your absolute risk — which captures your DNA and your lifestyle — is especially important. Our Beyond your DNA survey, where you can tell us a little more about yourself, helps us make your results as accurate as possible. The more details you can provide, the more accurate your risk assessment will be.
References
1
🔗 “Absolute versus relative risk” Cancer Research UK.
2
Fritsche L, Chen W, Schu M, et al. 🔗 “Cancer risk: What the numbers mean” Mayo Clinic.
3
Noordzij M, Dekker F, Zoccali C, et al. 🔗 “Measures of disease frequency: prevalence and incidence.” . Nephron Clin Pract 2010;115(1):c17-20. doi: 10.1159/000286345. Epub 2010 Feb 19. PMID: 20173345
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LAST UPDATED 02/02/2024
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