Social media headlines and evolving literature have highlighted the abysmal life expectancy of emergency room doctors.
For example, Dr. Ken Milne, the creator behind The Skeptics Guide to Emergency Medicine, recently shared this post on sobering life-expectancy data for ER physicians.
In this post, we delve into the contributing factors to the increased mortality risk among ER physicians, focusing on the health impacts of shift work. From cancer to cardiovascular disease and mental health challenges, we will explore how the demanding nature of emergency medicine affects the longevity and well-being of its practitioners.
So.. is it true? What they say about shift work?
The most heavily cited article on this topic was published by Brayne et al. in 2021 in the journal Lifestyle Medicine.[1]
The authors analyzed over 8000 physician obituaries published in the BMJ, subsequently extracting specialty, age, and cause of death. What’s important to note, is these obituaries were submitted voluntarily, the BMJ has a free obituary section where physician families can choose to submit an entry.
Of the submitted entries, ER doctor’s mean age of death was 58.7 years, with cancer being the leading cause of death (43%), followed by a tie between accidental injury (14%) and respiratory disease (14%).[1] For reference, the Canadian national average for cancer accounts for 25% of deaths [2].
The key limitation of this article was the sample size. Beyond selection bias, there were only 43 ER doctors analyzed, with a life-expectancy standard deviation of over 23 years. Contrastingly, the study included over 2500 primary care physicians. Clearly, we shouldn’t draw any meaningful conclusions on ER physician life expectancy from this publication.
Surprisingly when we turn to the literature, there aren’t higher-quality studies analyzing ER physician-specific mortality. There are two significant reasons for this:
- Emergency medicine is a relatively new specialty. The first Canadian ER residency was created less than 50-years ago, in 1980 [3]. Up until this time, general practitioners covered the ER and it is exceedingly difficult to tease out this data.
- There are limitations in conventional tracking and public databases on life expectancy by career.[4] Life expectancy data is often collected at broader levels by country or demographic group, rather than by vocation. While insurance companies and actuaries may have this data, itis not readily available to the public.
Nevertheless, the literature adds some credence to the physiologic rationale behind decreased life expectancy in Emergency Medicine providers.
The Harms of Shiftwork
Cancer
In 2007, the International Agency for Research on Cancer, under the World Health Organization, concluded that shift work is a probable human carcinogen.[5] Specifically, a Group 2A carcinogen. For reference, other substances in this same category of risk include insecticides like DDT, lead exposure, strains of HPV, and working in a petroleum refinery.[6]
More recently, their position statement was updated in 2019 and published in Lancet Oncology. identifying night-shift work as a human carcinogen.[7] Some of the strongest links for shiftwork-associated cancers are breast, prostate, and colorectal cancer.
For breast cancer, the evidence was definitive enough that in 2021 the US National Toxicology Program (NTP), classified night shift work as a known carcinogen for breast cancer[8] which puts it in the same category as Asbestos, HIV, and Tanning Beds.[6]
One of the largest studies establishing this link is the Nurse’s Health Study.[9]The study cited above was a cohort from this group, with over 78,000 women who worked rotating night shifts. For pre-menopausal women, the risk of breast cancer after working 1 – 14 years on rotating nights was increased by 23%. After 20-years of nights, the risk of breast was 66% higher than the control group.
“Women working rotating night shifts with at least 3 nights per month, in addition to days and evenings, have a moderately increased risk of breast cancer”. [9]
In males, there are similar links for prostate cancer. One systematic review of almost 2.5 million males found a 24% increased rate of prostate cancer in regular night-shift workers, with a suggestive dose-response relationship.[10]
In 2019, a Cochrane protocol was developed to help operationalize data for studies examining the effects of night shift work on over 16 types of cancers. The goal was to better identify the types of night shift work linked to cancer, and the dose-response relationship. For example, is a 16:00 – 01:00 shift harmful or is it just the 00:00 – 08:00 shift? And how do the cumulative years of shiftwork affect your individual risk?
To conclude, here are risk factors of shift workers thought to be at the highest risk of cancer by the Center for Disease Control and Prevention (CDC): I’ll leave you with an article from the Center for Disease Control and Prevention (CDC) website.[11] They highlight subsets of shift workers thought to be at the highest-risk of cancer.
- Beginning night shift work in early adulthood (such as before the age of 30)
- Night shift work of at least 3 hours between midxnight and 5:00 AM
- Frequent night work (3 or more nights per week)
- Long-term night shift work (10 or more years)
Cardiovascular Disease
Similar to cancer, there have been multiple publications and established links between shift work and cardiovascular disease.[12] Consider the following Canadian meta-analysis published in the British Medical Journal (BMJ) in 2012.[12] It analyzed over 2 million shift workers from 34 independent studies.
They found that shift workers have a 23% increased risk of myocardial infarction, and a 5% increased risk of ischemic stroke, independent of socioeconomic status (SES). SES is highlighted as a significant part of human longevity correlates to wealth.[13] That is to say, the rich generally live longer, due to increased access to healthcare resources, knowledge, and time to engage in healthy lifestyle behaviors. Nonetheless, being a physician or of a certain SES doesn’t change this associated link.
Mental Health
Shift workers suffer increased rates of mental health disorders, including depression, anxiety, insomnia, suicidal ideation, impaired cognition, and substance use.[14]
The following statistics are taken from a structured 2020 review involving 23 independent studies.[14]
- Over one in four shift workers may suffer from depression or anxiety [15].
- Shift work is associated with increased suicidal ideation (SI). An alarming 8-fold increased risk of SI exists for shift workers with self-reported insomnia.[14]
- Shift workers have higher rates of substance misuse, including sleep-promoting drugs, wake-promoting drugs, alcohol, and smoking.
- Shift workers experience higher levels of cognitive impairment in middle and older age.
Interestingly, the article highlighted that individual sleep chronotype, i.e. early-bird or night-owl, affects the experienced mental health consequences; early birds tend to show a lower tolerance for shift work, with increased cognitive and mental health impairment.[14]
TL/DR;
Shift work has clear evidence for health harms. We’re going to look into some of the proposed mechanisms and ways that we can mitigate these potential health impacts.
Melatonin Theory
At the core of shiftwork lies circadian rhythm disruption. Our pineal gland, which secretes melatonin, suppresses endogenous melatonin production in response to bright light exposure. Melatonin isn’t just involved in your sleep wake-cycle, but your body’s energy metabolism, immune function, DNA repair, and tumor suppression, with melatonin receptors throughout the body. [16] Melatonin production is suppressed in shift workers.
As outlined in the diagram above by Lingas (2023), melatonin can act as an antioxidant and free radicle scavenger, it enhances natural killer cell function, while also affecting lymphocyte proliferation and the expression of the tumor suppressor gene p53. Melatonin has a direct action on estrogen receptor binding, causing an inhibitory effect, which subsequently decreases blood estrogen.
This is one of the theories behind higher rates of breast cancer in shift workers.[9] Without melatonin inhibiting estrogen, women have higher circulating levels of estradiol, leading to increased growth and proliferation of hormone-sensitive cells in the breast. Particularly in shift workers, researchers have found higher levels of receptor-positive breast cancer, including ER+, PR+, and HER2+.[17]
Sleep Deprivation Theory
Underpinning shiftwork is often sleep deprivation. On average, night and shift workers who work early mornings, sleep 2-4 hours less than their daytime counterparts.[18] Reflect on the last time you switched to a night shift, and then afterwards back to days. Do you think you averaged 8 hours of sleep for every 16 hours you spent awake?
Note that even modest sleep deprivation, especially long-term, leads to marked impairment in your body’s immune function, including decreased natural killer (NK) cells and immune surveillance. [19]
Cardiovascular Theory
Increased cardiovascular disease rates may be partially attributable to higher circulating cortisol and norepinephrine levels in shift workers, as well as other important neurohormonal changes.[19] Your nocturnal surge in prolactin is decreased, whereas insulin shows an increased acute response to glucose challenges and insulin resistance develops. When working overnight, you have decreased levels of circulating leptin, which is the body’s satiety hormone influencing how snacky you likely feel. Over time, these endocrine changes can lead to increased blood pressure, insulin resistance, and metabolic syndrome.
Telomeres
The last theory to cover is that of telomeric shortening. Above is a picture of Turritopsis Dohrnii, the immortal jellyfish that can live over 1000 years, with mutations in telomerase that preserve telomeres.
Studies summarized by the original WHO Study were mostly consistent in showing enhanced telomere shortening in shift workers a hallmark of aging.[5] Furthermore, a dose-response relationship of increased telomeric shortening to increased cardiac rhythm disruption has been demonstrated in animal models.[20]
Conclusion
Working in emergency medicine is an immense privilege, but it’s important to acknowledge and address the significant harms associated with the profession and shiftwork. Although the social media claim that ER physicians have a life expectancy of less than 60 years is inaccurate, research indicates that shift workers, including ER physicians, tend to have a below-average life expectancy. They face higher risks of cancer, cardiovascular disease, and mental health issues due to factors like circadian rhythm disruption, melatonin signaling interference, endocrinologic changes, sleep deprivation, and telomeric shortening. Therefore, prioritizing health through proper nutrition, exercise, sleep, and overall wellness is essential.
References
[1] A. B. Brayne, R. P. Brayne, and A. J. Fowler, “Medical specialties and life expectancy: An analysis of doctors’ obituaries 1997–2019,” Lifestyle Med., vol. 2, no. 1, p. e23, Jan. 2021, doi: 10.1002/lim2.23.
[2] D. R. Brenner et al., “Projected estimates of cancer in Canada in 2024,” Cent. Nerv. Syst., vol. 196, no. 18, 2024.
[3] R. Elyas, “31. The birth of a new specialty: The history of emergency medicine in Canada,” Clin. Invest. Med., vol. 30, no. 4, p. 44, Aug. 2007, doi: 10.25011/cim.v30i4.2791.
[4] Dr. R. Deshpande and V. Uttarkar, “Life Expectancy using Data Analytics,” Int. J. Res. Appl. Sci. Eng. Technol., vol. 11, no. 4, pp. 972–978, Apr. 2023, doi: 10.22214/ijraset.2023.50140.
[5] K. Straif et al., “Carcinogenicity of shift-work, painting, and fire-fighting,” Lancet Oncol., vol. 8, no. 12, pp. 1065–1066, Dec. 2007, doi: 10.1016/S1470-2045(07)70373-X.
[6] American Cancer Society, “Known and Probable Human Carcinogens.” [Online]. Available: https://www.cancer.org/content/dam/CRC/PDF/Public/633.00.pdf
[7] E. M. Ward et al., “Carcinogenicity of night shift work,” Lancet Oncol., vol. 20, no. 8, pp. 1058–1059, Aug. 2019, doi: 10.1016/S1470-2045(19)30455-3.
[8] National Toxicology Program (NTP), “National Toxicology Program Cancer Hazard Assessment Report on Night Shift Work and Light at Night.”
[9] E. S. Schernhammer et al., “Rotating Night Shifts and Risk of Breast Cancer in Women Participating in the Nurses’ Health Study,” JNCI J. Natl. Cancer Inst., vol. 93, no. 20, pp. 1563–1568, Oct. 2001, doi: 10.1093/jnci/93.20.1563.
[10] L. Xie, D. Rao, H. Yu, Y. Bai, and X. Zheng, “Does night-shift work increase the risk of prostate cancer? a systematic review and meta-analysis,” OncoTargets Ther., p. 2817, Oct. 2015, doi: 10.2147/OTT.S89769.
[11] C. Lawson, E. Whelan, T. Carreon-Valencia, and C. Caruso, “Recent News about Night Shift Work and Cancer: What Does it Mean for Workers?,” U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Oct. 2019. doi: 10.26616/NIOSHPUB2015115revised102019.
[12] M. V. Vyas et al., “Shift work and vascular events: systematic review and meta-analysis,” BMJ, vol. 345, no. jul26 1, pp. e4800–e4800, Jul. 2012, doi: 10.1136/bmj.e4800.
[13] R. Chetty et al., “The Association Between Income and Life Expectancy in the United States, 2001-2014,” JAMA, vol. 315, no. 16, p. 1750, Apr. 2016, doi: 10.1001/jama.2016.4226.
[14] J. P. Brown, D. Martin, Z. Nagaria, A. C. Verceles, S. L. Jobe, and E. M. Wickwire, “Mental Health Consequences of Shift Work: An Updated Review,” Curr. Psychiatry Rep., vol. 22, no. 2, p. 7, Feb. 2020, doi: 10.1007/s11920-020-1131-z.
[15] B. I. Voinescu, “Common Sleep, Psychiatric, and Somatic Problems According to Work Schedule: an Internet Survey in an Eastern European Country,” Int. J. Behav. Med., vol. 25, no. 4, pp. 456–464, Aug. 2018, doi: 10.1007/s12529-018-9719-y.
[16] E. C. Lingas, “A Narrative Review of the Carcinogenic Effect of Night Shift and the Potential Protective Role of Melatonin,” Cureus, Aug. 2023, doi: 10.7759/cureus.43326.
[17] J. Hong et al., “The relationship between night shift work and breast cancer incidence: A systematic review and meta-analysis of observational studies,” Open Med., vol. 17, no. 1, pp. 712–731, Apr. 2022, doi: 10.1515/med-2022-0470.
[18] G. Kecklund and J. Axelsson, “Health consequences of shift work and insufficient sleep,” BMJ, p. i5210, Nov. 2016, doi: 10.1136/bmj.i5210.
[19] G. Costa, E. Haus, and R. Stevens, “Shift work and cancer – considerations on rationale, mechanisms, and epidemiology,” Scand. J. Work. Environ. Health, vol. 36, no. 2, pp. 163–179, Mar. 2010, doi: 10.5271/sjweh.2899.
[20] E. Grosbellet et al., “Circadian desynchronization triggers premature cellular aging in a diurnal rodent,” FASEB J., vol. 29, no. 12, pp. 4794–4803, Dec. 2015, doi: 10.1096/fj.14-266817.
Presume there are intervention studies with melatonin or estrogen in shift workers?