21.3: Health Risks

In general, people tend to underestimate high probabilities and overestimate low probabilities, and this holds in risk assessment. You hear about rabies shots and cholera shots. These are both serious diseases, and it makes sense to get a rabies shot for your dog, or a cholera shot for yourself if you are traveling to countries where it is a danger. But only 1-3 cases of rabies are reported in the United States each year, and on average there are only 6 reported cholera cases in the U.S. per year. So, it isn’t the best use of your time to think about ways to avoid rabies or cholera (not to mention the plague, which sounds terrible, but afflicts only an average of 7 Americans each year and is rarely fatal if treated).

It is true that anyone can be stricken by a rare disease, and it won’t be much comfort for that person to hear that their probability of getting it was low. But everything we do carries some risk, and we simply can’t plan to deal with every risk life offers. The best approach involves two steps, both of which involve probabilities.

1. Identify the large risks in your (or your family’s) life.
2. Adopt measures that have the highest probability of helping you avoid those risks.

We have considered the factors that bear on the second issue in earlier chapters, so here we will focus on the first. But one general point is worth emphasizing before turning to details. Whenever people are worried about a risk, someone will come along with a way for you to avoid or reduce it— for a price. If their remedy sounds too good to be true, it probably is. On the other hand, we do know a good deal about how to reduce many of life’s most serious risks, and often the ways to do it don’t require you to spend any money at all.

The Big Three

Figure 21.2.1 on death rates in 2015 gives a good indication of the causes of death in America over the recent past (although deaths from COIVD 19 are obviously going to be among the top three for this year). As the table shows, there are three big killers: heart disease, cancer, and stroke. Your chances of being killed by one of these is much, much greater than your chances of dying in any sort of accident, or from anything else. Fortunately, there are also reasonably simple steps you can take to greatly lower your risk from the Big Three.

Heart Disease

When we think of heart-related deaths, most people think immediately of cardiac arrest, or heart attack. But heart disease-which can lead to heart attack-is a much bigger animal. Coronary artery disease occurs when the arterial walls) which carry blood to the heart) become lined with a buildup of cholesterol, causing the pathways to narrow. This means less blood gets to the heart, which means the heart must work harder, and may develop an irregular beating rhythm, which, over time can lead to heart failure. If an already narrowed path becomes blocked by a blood clot, heart attack occurs. And if those clots make their way to the brain, stoke occurs. While even the best-kept heart will eventually wear out, it is well known that certain behaviors increase the risk of heart disease, and lead to it developing earlier in one’s life. Smoking, poor diet, and lack of exercise greatly increase one’s risk of death from heart disease.

Cancer

Cancer is a blanket term that covers several diseases that involve unregulated growth of cells. The probability that an American male will develop cancer at some point is 1/2, and the probability that an American woman will is 1/3. The causes of cancer aren’t fully understood, though there are clearly different risk factors for different types of cancer, so there are no universal precautions. There are however, relatively easy ways to decrease your risk of some kinds of cancer (smoking is a very large risk factor for lung cancer and several other cancers; and spending ling hours in the sun is a risk factor for skin cancer). There are also easy preventative measures against some forms of cancer, For instance, getting your tweens vaccinated against HPV greatly reduces their (or their future partners’) risk of getting cervical cancer as adults.

Lung Disease

Like cancer, there are several forms of lung disease, all characterized by breathing difficulties. Although it can be hereditary, it is most often caused by environmental exposures. Smoking is the highest risk factor, but exposure to dust, pollen, and chemicals cause it to develop as well. The harm to the lungs caused by these irritants accrues over many years, and by the time its effects are noticeable, the damage is often irreversible. Wearing face coverings to protect against inhalants might seem like overkill when you’re young, but it could ad years to the end of your life. When we’re young, we don’t worry too much about catching infections that we’re confident we’ll recover from. But the bronchitis you bounced back from when 20 left you just that much more vulnerable to more serious problems later in life.

Other Causes of Death

Some of the other leading causes of death will probably surprise you. For example, pneumonia and influenza are eight on the list, diabetes is seventh, and blood poisoning isn’t all that far behind.

Risk Factors

It is always possible to get more informative risk ratios by making the target group more precise. Instead of looking at the rate of strokes in the entire population, we could look at the rate of strokes by age group, e.g., from 20- 30, 21-40, etc. There is a tradeoff here between more precision and more complicated statistics. But the general idea here is important. Almost one in four Americans will die of heart disease, but the risk is much higher in some groups than in others. If several members of your family had heart disease, your risk is higher; if you are over fifty or overweight, the risk goes up. Again, strokes are the third leading cause of deaths among Americans, but over two thirds of stroke victims are 65 or older.

Just as we can consider smaller subgroups, rather than looking at all Americans, we can consider larger groups by looking at a number of countries, or even at the entire world. This will often change risk factors, since the risks facing people in developing countries are often quite different from those facing Americans. For example, the fifth highest cause of death world-wide in 2016 was diarrheal diseases. They killed 1.4 million people worldwide, but since about 99% of the deaths occurred in developing countries, they don’t show up as risk factors for Americans.

If you are really concerned about a given risk factor, you can usually find statistics that break the risk down by groups, and you can see what the risk is for the group you are in (e.g., males between 18 and 28 years of age). But even a simple break down like the one in Figure 21.2.1 gives us a pretty good idea about risks that can lead to death.

Smoking

Smoking is the single greatest preventable risk factor in America. About 480,000 people die each year from smoking related deaths (this isn’t reflected directly in our table, but smoking leads to items, like heart attacks and cancers, that are on the list). Males smokers reduce their life expectancy by over eight and a half years, and female smokers reduce theirs by over four and a half years. Being overweight is also a major risk factor for several of the leading killers (not just heart attacks, but also cancer).