BE A SMARTER READER: HOW TO UNDERSTAND “RISK” IN HEALTH STUDIES
We’re always having articles thrown at us about which juice cleanse is the best for removing toxins, which food we should add to our diet to really rev up our metabolism, or how much sex we should be taking part in for our mental health to prosper. But how the eff do we know what data to trust? And how, if we have no medical background, can we be educated readers of the studies making such miraculous claims?
To begin, as Our Bodies Our Selves so nicely puts its, “Risk indicates whether or not a treatment or behavior (an exposure) is associated with an increased likelihood of developing a disease or condition (an outcome).”(1)
There are two types of risk that comes up in research studies: relative risk and absolute risk. Understanding the difference between the two can help you understand your own risk of developing different health issues and help you better navigate the studies that pop up in your Facebook feed.
RELATIVE RISK: WHAT IS IT?
Relative risk shows us the strength of the association between exposure and outcome, or in other words, it tells you how much something that you do (let’s say, eat your daily portion of vegetables) can change your risk for developing a health issue, compared to your risk if you don’t do that thing (if you don’t eat your veggies). It is used to assess the importance of a particular factor or treatment in the development of a disease or condition.
This is expressed as a percentage increase or decrease—if your action does not change your risk, then the relative risk reduction would be 0% aka no difference. If your action lowers your risk, let’s say by 20% for example, compared to someone who does not take that same action, then you would reduce your relative risk by 20%. In general, relative risk is used to compare the risk between two groups of people and the difference in their actions.
GOTCHA. AND ABSOLUTE RISK?
Absolute Risk “...describes the effect of an exposure on an outcome in the general population (as opposed to comparing specific groups). In the population overall, how harmful is an exposure? What is the likelihood of developing a particular condition? Absolute risk provides answers to these questions.”(2)
WHAT’S THE DIFFERENCE AND WHY SHOULD I CARE?
In order to understand how specific factors actually affect your likelihood of developing a health conditions, you need to know the absolute risk.
While relative risk compares your risk of developing a condition to someone else’s risk of developing that same condition, absolute risk is your own risk, not compared to any other group or individual.(3)
This is important to keep in mind, because sometimes, studies can report numbers that sound scary, like a 75% risk increase for developing a certain disease. This is typically a relative risk—so it is an increase in comparing two groups, not an increase in the general population.
It’s vital to understand research and how it can help us make our daily choices and to understand our own risk of developing a condition or disease. But, it’s also crucial to remember that we are bio-individuals, meaning, we are all very different. So, in addition to using science-based evidence as a tool in decision making around our health, we also need to take our own values and personal body intelligence into consideration.
By: Molly Schwartz, Sex Positive Advocate and Public Health Worker in NYC
(1) Norsigian, Judy. Our Bodies, Ourselves. New England Free Press, 1972.
(2) OBOS Navigating Health Care Contributors. “How to Find, Read & Understand Health Research Studies.” Our Bodies Ourselves, 15 Oct. 2011, www.ourbodiesourselves.org/book-excerpts/health-article/understanding-health-research-studies/.
(3) Newson, Louise. “Absolute Risk and Relative Risk | Medical Definitions.” Patient.info, Jan. 2018, patient.info/health/nhs-and-other-care-options/features/calculating-absolute-risk-and-relative-risk.