What I Didn’t learn in Medical School: The Leading Causes of Death
We memorize lots of things in medical school. We don’t just memorize the 12 cranial nerves, but we learn their paths, the muscles they innervate, what those muscles do, etc. We memorize complex metabolic pathways, along with the enzymes and cofactors required for each step. We memorize all the muscles, nerves, arteries, and veins throughout the body (As a foreign medical student, I had to learn these in Spanish, too). And of course, we learned the leading causes of death in the world, and in the US. The lists vary somewhat from nation to nation, and from time to time. Diarrhea, malaria, tuberculosis, and HIV/AIDS are still on the top 10 list in low-income nations while in the US, diabetes and chronic kidney disease are relatively new to the list. What I didn’t learn in medical school was that the majority of the diseases that kill most of the world’s people are preventable. Some are even reversible once you get them. Let’s explore the most recent list for the US in more detail (I am excluding Covid-19 which has been on everyone’s top 3 list for both 2020 and 2021, after heart disease and cancer).
Heart Disease: Almost 650,000 Americans die of heart disease each year in the US. This is 1780 people per day, the equivalent of 4 or 5 jumbo jet crashes every day. Put another way, it’s a little more than one death from heart disease every minute of every day. Every year. And most of these deaths can be prevented, or at least delayed by years, with just a few lifestyle changes.
Don’t smoke. If you do, stop. If you stop smoking, you reduce your risk of heart disease by 50%!
Stay or get physically active: a 30-minute brisk walk 5 times per week lowers your chance of heart disease by 30%.
Eat a healthy diet, predominantly whole food and plant based. Eliminate processed meats and sugar-laden beverages. Reduce intake of animal proteins and dairy products. Eat plenty of vegetables, beans and legumes, nuts and seeds, and fruits.
Avoid obesity. Keep your BMI under 25. (see b and c above)
Avoid type 2 diabetes; this is especially important for the 88 million prediabetics in the US. Nearly 100% of type 2 diabetes is avoidable and most is reversible, especially in the first few years after diagnosis. The best way to avoid type 2 diabetes is to not be overweight. More than 90% of people with type 2 diabetes are overweight (BMI of 25-29.9) or obese (BMI > 30). Not all overweight people get diabetes, but overweight people are 3X more likely to get diabetes and obese people are 7X more likely. Enough said.
Cancer: Cancer, number 2 on the top 10 list, causes about 600,000 deaths in the US annually. Let me be clear; not all cancer can be prevented. Indeed, the biggest risk for most adult cancers is aging itself. However, much can be done to reduce your risk of developing and dying from cancer. I’ll focus on the top 3 for men and women, that account for about half of all cancer deaths.
Lung cancer is the leading cause of cancer deaths in both men and women (Interestingly, lung cancer wasn’t on the list for women in the 1960’s; remember the cigarette ads targeting women, saying, “You’ve come a long way, baby.” I guess they were right.) The likelihood of getting lung cancer can be greatly reduced by never smoking or quitting if you do; 90% of lung cancer is attributable to cigarette smoking. Not all smokers will get lung cancer, but 10-15% will. Of course, smokers are far more likely to develop other diseases on the top 10 list including other cancer, heart disease and chronic lung disease. Cigarette smoking is the leading cause of preventable disease and death in the United States (CDC). I should point out that not everyone who gets lung cancer dies. Early detection of lung cancer in smokers using low dose chest CT scans is effective in detecting early and more treatable lung cancers.
Prostate (men) and breast cancer (women)
Prostate cancer: not all prostate cancer can be prevented, especially as men age. 75% of prostate cancer occurs in men over 75. The most effective way to prevent death from prostate cancer, a slow-growing malignancy, is to detect it an earlier stage. Regular screening for men beginning at age 55 (earlier in African American men who are at higher risk). (Screening protocols vary). Sadly, only about half of men in the US had a PSA (prostate-specific antigen) blood test in 2018. There is evidence that eating a healthy diet (eating less meat, processed foods, and dairy products and eating more fish, vegetables, fruits, and nuts (especially Brazil nuts, only 1-2 daily, that are high in selenium) can reduce your risk of many cancers, including prostate cancer.
Breast cancer: breast cancer is the second most common cause of death from cancer in women, second only to lung cancer (skin cancer is the more common but less likely to result in death). It accounts for about one-third of all new cancers in women. However, the lifetime risk for a woman to develop breast cancer is about 1 in 8, and the chance of dying from breast cancer is less than 1 in 40. Indeed, the death rate from breast cancer has been steadily declining, and for many women with breast cancer, it has become a chronic condition. The major reason for the decline is the widespread use and availability of screening tests, including mammography, ultrasound (for masses and dense breasts) and breast MRI (for high-risk patients) as well as prophylactic mastectomy. Like prostate cancer in men, age is one of the most significant risk factors; most breast cancers are found in women over 55 years of age. About 5-10% of breast cancers are hereditary; the most common mutations associated with breast cancer are the BRCA1 and BRCA2 genes. Nonetheless, there are certain modifiable risk factors that can reduce the likelihood of a women getting breast cancer including: limit alcohol to one drink a day or less; maintain a healthy weight (the correlation of weight to breast cancer (and many other cancers) has been clearly established, especially in postmenopausal women) and; be physically active (150 to 300 minutes of moderate activity, like a brisk walk, per week, or 75-150 minutes of vigorous activity (activities that cause an increased heart rate, seating, and a faster breathing rate). While studies are variable, there is evidence to suggest that a healthy diet, high in vegetables and fruits, lower in sugar, processed foods and processed meats might reduce a women’s risk of developing breast cancer.
Colorectal cancer: colorectal cancer is the third leading cause of cancer death in both men and women. It also is one of the most preventable malignancies. Colorectal cancer most frequently starts in adenomatous polyps in the colon, that if left in situ, can become malignant over 10-15 years. Hence, as these polyps can be identified and removed in most patients by colonoscopy, colon cancer can be prevented in most people. Some people develop colorectal cancer before the normal age at which screening colonoscopies are recommended; screening is recommended between 50 to 75 years of age, although some recommend begin screening at 45 years of age. While colonoscopy and flexible sigmoidoscopy every 5 to 10 years are the “gold-standard” screening tests, other screening tests include high-sensitivity guaiac fecal occult blood test (HSgFOBT) or fecal immunochemical test (FIT) every year; stool DNA-FIT every 1 to 3 years; computerized tomography (CT) colonography—so-called—virtual colonoscopy--every 5 years. These screening tests are highly effective, and they can prevent at least half of all colorectal cancers. Unfortunately, only about half of eligible people undergo screening for colon cancer! However, there are other things one can do to reduce their risk of developing colorectal cancer: maintain a healthy weight; don’t smoke, stop if you do; be physically active; drink alcohol in moderation (probably less than one drink per day), limit red meat, especially processed meats (e.g., bacon, sausage, bologna, hot dogs, etc.); and get enough Vitamin D, folate and calcium.
Unintentional injuries/Accidents: While industrial accidents resulting in death have become far less common over the last 50 years, all too many people still die from accidents. Indeed, unintentional injuries are the leading cause of death for all age groups between 1-44 years old. Motor vehicle accidents are the leading cause of fatal accidents, accounting for 42,000 deaths per year, down from a peak of 54,000 in 1973. The number dropped steadily until about 10 years ago, primarily due to safety features in cars (seat belts, shoulder straps, and air bags) as well as automobile design and manufacturing safety improvements that are made to absorb the impact of a collision, and lower speed limits. More recently, there has been an increase in motor vehicle accidents resulting in death, with distracted driving a likely causal factor. Alcohol-impaired drivers account for about 28% of auto fatalities. While not all accidents can be prevented, to reduce your risk of having a fatal accident: wear seat belts; don’t drinking and drive; don’t speed and don’t be distracted (e.g., don’t text or email while driving). Accidental drug overdoses, sadly, account for another 35,000 deaths per year.
Chronic Lung Disease: Chronic Obstructive Pulmonary Disease (COPD) is a common, yet preventable disease that kills 160,000 Americans per year. Tobacco exposure is the main risk factor for development of COPD, although it is possible to develop COPD and never having smoked (as many as 1 of 4 patients with COPD never smoked). However, smoking accounts for 8 out of 10 COPD-related deaths. More than one-third of the 16 million Americans with COPD still smoke. Secondhand smoke, especially during childhood and adolescence can impair lung growth and development, increasing the risks for COPD later in life. To prevent most cases of COPD, don’t smoke and quit if you do. To reduce: your chance of dying from COPD if you do smoke, quit. Avoid prolonged exposure to second-hand smoke.
Strokes and Cerebrovascular Disease: Cerebrovascular diseases include stroke (ischemic, hemorrhagic, or embolic), transient ischemic attacks (TIA), aneurysm and cerebral vascular malformations and account for 146,000 deaths in the US each year. The risk factors for developing a stroke or aneurysm include aging; cigarette smoking, hypertension; diabetes; elevated cholesterol; unhealthy diet; lack of exercise; drug use, especially cocaine; and heavy alcohol consumption. In 2016, an article in the Lancet reported that 91% of all strokes could be prevented by 10 heathy lifestyle changes and healthcare improvements including: healthy diet (more vegetables, fruits, whole grains, nuts, seeds, omega-3 fatty acids, polyunsaturated fats, more fiber, and less saturated fat, less red meat, less processed meat, less sugary drinks), don’t smoke, exercise regularly, don’t drink to excess, stay lean, and better control of diabetes, hypertension and elevated cholesterol/lipids.
Alzheimer’s/Dementia: Alzheimer’s Disease, the most common cause of dementia, is the 6th leading cause of death overall, but it might be the third leading cause of death in the elderly, only surpassed by heart disease and cancer. Age is the single biggest risk factor; most people present with symptoms after age 65. The risk doubles every 5 years after that, so that by age 85, about 1 in 3 people with have dementia. Genetics and family history are also important risk factors. While this might be one that is not known to be preventable (as of this writing), much recent research has shown strong correlations between heart health and brain health. The disease is much more common in the US than Japan, while Latinos and African Americans have 1.5 and 2X the risk of whites, respectively. The risks of developing Alzheimer’s are increased in people with heart disease, diabetes, stroke, high blood pressure and high cholesterol. Can we prevent or delay the onset of Alzheimer’s? Time will tell.
Diabetes: Diabetes is relatively new to the list and rising fast. When I was in medical school, about 2.5% of the population had diabetes; today more than 8% of Americans have diabetes (even higher in African Americans, Native Americans, and Latinos); that’s right, the incidence has more than tripled in just the last 30 years. Hence, about 34 million Americans have diabetes (1 in 5 are undiagnosed so don’t even know it) and another 88 million have pre-diabetes (8 of 10 don’t know it!). Today about 95% of diabetes is type 2. The factors that have led to this increase are obesity and weight gain. Obesity, by far, is the largest single risk factor for the development of type 2 diabetes. It is worth noting that not all obese people (BMI > 30) will develop diabetes; indeed, only about 25% of morbidly obese people (BMI>40) will. However, 90% of diabetics are overweight or obese. It is believed that the years of elevated blood sugars result in increased inflammation throughout the body, eventually leading to cardiovascular disease, especially heart attacks, heart failure, stroke, kidney disease, blindness, and coma. Virtually all of these complications of diabetes are preventable, with optimal control of blood sugars when diagnosed with diabetes. Unfortunately, only about 50% of known diabetics (remember 1 in 5 don’t even know they have it) are considered well-controlled, as determined by HbA1C measurements.
Influenza/Pneumonia: acute lung infections continue to be a leading cause of death in the US, causing 56,000 deaths per year. Age is the greatest risk factor, with 90% of the deaths occurring in those age 65 and older. Vaccines against influenza and pneumococcal pneumonia are immensely helpful in reducing the risk of infection and death, but they are not 100% effective. However, natural immunity can be boosted, according to the Cleveland Clinic, by eating a healthy diet, not smoking, getting adequate sleep, and getting adequate amounts of vitamins A, C, D and E, as well as zinc, selenium, iron and folate through diet or supplements.
Chronic Kidney Disease (CKD): Chronic kidney disease results from a gradual, yet progressive, loss of kidney function, resulting in the accumulation of toxic chemicals normally filtered by the kidney and excreted in the urine, as well fluid and electrolyte imbalances. So-called end-stage kidney disease can only be managed with dialysis or kidney transplant. While there are numerous causes of CKD, the most common causes of CKD are poorly controlled hypertension and poorly controlled diabetes, which together account for two-thirds of all cases of CKD. Hence, risk factors for the development pf CKD are diabetes, hypertension, heart disease [this is the most common cause of death for people with CKD], smoking, obesity, and age. Excessive and prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs) can also lead to kidney damage.
Suicide: Suicide is the 10th leading cause of death in the US, accounting for 47,000 deaths annually. However, when age is taken into consideration, suicide is the second leading cause of death in people ages 10-34. Needless to say, by definition, all suicide is preventable. Connection to family and community support and easy access to mental health professionals are essential in reducing the number of suicides. Risk factors include depression, substance abuse, childhood abuse or neglect, childhood trauma, exposure to excessive bullying, stress, and anxiety.
In conclusion, nine of the top ten causes of death in the US, which alone account for 75% of all deaths, are modifiable and/or preventable. Nine general principles for a healthy and longer life include:
Don’t smoke; if you do, stop.
Limit alcohol intake to less than 1 drink per day for women and 2 drinks per day for men. Recent evidence suggests even this is too much. Don’t drink and drive!
Limit consumption of animal proteins in diet; increase consumption of plant-based sources including seeds and nuts.
Limit the consumption of dairy products (after done breastfeeding!)
Eliminate sugary beverages and sweets from your diet; drink lots of water instead.
Eat foods that you can identify (as well as their source) on your plate like vegetables, fruits, beans, legumes (e.g., chickpeas, green peas, lentils), seeds (e.g., flax, chia, hemp, sesame, pumpkin, and sunflower seeds) and nuts (e.g., almonds, pecans, hazelnuts, macadamia, and walnuts)
Exercise, at least 30 minutes of brisk walking 5 times per week; strength or resistance training at least twice a week is helpful to promote bone health and to reduce falls, particularly in the elderly
Incorporate meditation/relaxation techniques into your daily activities
Get enough sleep. For adults, in general, this means between 7.7 to 8.5 hours per night (longer when younger; less when older).
No one lives forever. The goal is to be as healthy as we can for as long as we can. Along with all the other things medical students, residents and fellows memorize should be the 9 things noted above. They should understand the principles and practice of change behavior and learn how to conduct motivational interviews. They should nudge their patients towards healthier behaviors, eventually getting them to switch from unhealthy practices to healthy lifestyle changes that will prolong their lives, keep them healthy longer and significantly reduce the total cost of healthcare.
