Cambridge O Level Biology · Syllabus 5090 · Transport in Humans
Risk Factor
What is Risk Factor?
A risk factor is something that increases the probability that a person will develop a particular disease, without guaranteeing that they will. For coronary heart disease the recognised risk factors include diet, physical inactivity, smoking, prolonged stress, inherited predisposition, increasing age and biological sex. Some of these can be changed by a person's own choices and are described as modifiable; others, such as age and inheritance, cannot.
This definition is part of the Transport in Humans chapter in Cambridge O Level Biology.
Common mistakes with Risk Factor
- “Smoking causes coronary heart disease, so a smoker will get it.” CorrectSmoking is a risk factor: it raises the probability of the disease across a population. It does not guarantee the disease in any individual, and non-smokers can develop it too.
- “Smoking causes coronary heart disease, so every smoker gets it.” Why wrongIt treats a change in probability as a certainty for an individual. WriteSmoking is a risk factor: it increases the probability of coronary heart disease. It does not guarantee it, and people who have never smoked can develop the disease too.
Questions students ask about Risk Factor
Is a risk factor the same as a cause?
No. A risk factor increases the probability that a person will develop a disease; it does not guarantee it. A person with several risk factors for coronary heart disease may never develop it, and a person with none of the modifiable risk factors still may.