4.18: Risk Factors and Protective Factors
- Page ID
- 116203
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The term "Risk Factor" is very specific in epidemiology -- much more specific that what we mean when we talk about risk in ordinary English. I want to make sure that everyone understands what a "risk factor" is, so even though you have seen this term already, it's worth a quick review. And while we're at it, we might as well also define a risk factor's opposite -- a protective factor (or resiliency factor).
A risk factor is something associated with a higher chance (higher probability) of developing a certain disease or injury, or of adopting a certain health behavior. It may or may not be an actual cause of that disease or injury. Here are some examples:
- Smoking tobacco is a risk factor for lung cancer. (In this case, the risk factor, tobacco, is also an proven cause of the disease, cancer.)
- Young age is a risk factor for motorcycle crashes. (One's age doesn't cause the crash -- but maybe something associated with younger age does, like being more prone to showing off, or being less experienced, or driving a poorer-quality motorcycle.)
- Having friends who vape is a risk factor for starting to vape. (This risk factor is pretty obvious -- but it does suggest that addressing the norms within a peer group might be a good prevention strategy.)
A protective factor (also called a resiliency factor sometimes) is something associated with a higher chance of avoiding disease, injury or some other bad outcome. Again, it may or may not be an actual cause of that outcome.
- Having a mentor is a protective factor that protects against school drop-out.
- Living in an urban (versus a rural) setting is associated with a lower chance of suicide.
Public health programs often use risk factors to identify the populations that need the most focus and resources. They are also used in the design of programs (or policies), as we generally try to reduce exposure to risk factors and increase protective factors.
Risk factors are imperfect predictors of disease.
- Some people with the disease won't have the risk factors.
- Some people with the risk factors won't have the disease.
- But still, those with the risk factors are more likely to develop the disease than people who do not have those risk factors.
Don't mix up risk factors and health consequences
In ordinary English, we might say something like, "Losing your sight is one risk of diabetes." But losing one's sight is not a "risk factor" for diabetes! Why? A risk factor is something that correlates with the onset of a disease (or injury). Losing one's sight is a consequence of diabetes. People who are blind are not at greater risk of developing diabetes in the first place -- rather, the disease can cause poor vision.
Think about the timeline of development of a disease (or injury). The risk factor must be present either before the disease (or injury) starts, or at the same time. If it only shows up AFTER the disease or injury starts, then it is probably a health consequence (or maybe a coincidence), not a risk factor.
This is one of the most common mistakes students make in HLTH 54. Make sure you understand what a RISK FACTOR is!Try using the term in ordinary conversation, correctly, to get more familiar with this public health terminology.
Examples:
- Road is poorly lit at night (risk factor) leads to car crash (injury). The road must be dark BEFORE or WHILE the car goes on it, in order to influence the crash. Not after the crash.
- Person who gets cancer loses their hair (health consequence). But being bald is not a risk factor for cancer!