Firefighters and Coronary Heart Disease: A Brief History on Research and Analysis

From Fire Engineering, Dec 6 2019

By Aditya Shekhar

Whether we want to admit it or not, firefighting and emergency services in general can be a dangerous profession. On firegrounds, there are hazardous materials, flames, heavy machinery, and potentially insecure structures. Responding to emergencies, especially with lights and sirens, dramatically increases the likelihood of traffic accidents. The stress of firefighting and the memories of certain calls can leave permanent scars in the form of post-traumatic stress disorder and other forms of mental illness. However, there is one risk that doesn’t receive as much coverage in the firefighting world: heart disease.

Data from the National Fire Protection Association found that, of the 60 firefighter fatalities that occurred in 2017, 29 were because of sudden cardiac death. Firefighters, as an occupation, have some of the highest rates of heart disease, heart attacks, and sudden cardiac death. There have been several studies published examining firefighters’ unique risk profile and the epidemiology of heart disease in the fire service.

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One of the first studies of the hearts of firefighters was published in 1975 by R.J. Barnard and H.W. Duncan in the Journal of Occupational Medicine. They looked at the heart rates of firefighters responding to emergencies and when engaged in firefighting. Less than a minute after the tones dropped, they recorded an average increase in heart rate of 47 beats per minute. During actual firefighting, researchers recorded unusually prolonged periods of tachycardia. They concluded that firefighting creates states of high anxiety, which then leads to tachycardia.

An early study looking at the relationship between firefighting and heart disease was published in the American Journal of Public Health in 1992 by Dr. James Friel and Dr. Michael Stones. After interviewing 200 Canadian firefighters in 1987 and 1988, they found high levels of obesity and high cholesterol, each being significant risk factors for heart disease. However, these are also modifiable risk factors, meaning that they can be changed with lifestyle modification or pharmacological therapy.

A few years later, Glueck and colleagues published a study in the American Journal of Industrial Medicine (1996). Beginning in 1984, they recruited 806 firefighters without coronary heart disease (CHD). They followed each firefighter for an average of 6.4 years and looked at participants’ weight, blood pressure, fasting glucose, and lipid profile, among other risk factors for CHD. If a participant was found to have high levels of risk, they were advised on how to reduce their risk, given an Electroencephalogram stress test and a thallium scan. Over the course of the study, seven men had heart attacks and 15 developed coronary heart disease. These 22 men were more likely to be smokers, have a family history of heart disease, have higher blood pressures, have higher low-density lipoproteins (LDLs) and total cholesterols, and higher triglycerides. That being said, the CHD rate found by the study was lower than a comparable nonfirefighting population. Researchers concluded that most of the participants’ risk stemmed from modifiable lifestyle choices. (It’s worth noting that this study specifically recruited participants without any heart disease at the outset and from one department only, which presents a selection bias.)

One of the most prominent researchers on the link between firefighting and heart disease is Dr. Stefanos Kales of Harvard’s T.H. Chan School of Public Health. A 2003 study conducting by Kales and several colleagues published in Environmental Health looked at the CHD-related deaths of 52 male firefighters to better understand what sorts of activities precipitated their fatal cardiac events and whether certain fire department duties might be more likely to lead to CHD-related death.

In their background research, they found that, from 1977 to 2002, CHD accounted for 45 percent of on-duty deaths. For reference, CHD was attributed to just 22 percent of on-duty deaths among police and detectives and 11 percent of emergency medical services (EMS) providers. Although the disease may be underlying, researchers also found that specific duties were likely to trigger a CHD-related death. For instance, they noted that actual suppression accounts for less than two percent of a firefighter’s duties but up to 36 percent of deaths. Responding to emergencies also increased the risk of a CHD-related death five-fold. Interestingly, only six percent of CHD-related deaths came during EMS runs (even though EMS calls represent most of the calls for many departments). Unfortunately, most firefighters who experienced CHD-related fatalities had not undergone a fire department medical exam within the previous two years.

Kales also examined a larger sample of firefighter deaths in a 2005 study published in the New England Journal of Medicine. He looked at the Federal Emergency Management Agency’s data on all firefighter deaths from 1994 to 2004 (excluding deaths because of the 9/11 attacks) and examined the ones that were found to be CHD-related. His research showed that 32.1 percent of deaths occurred during fire suppression, 17.4 percent occurred during returning from an alarm, 15.4 percent occurred during nonemergency duties, 13.4 percent occurred during responding to an alarm, and 9.4 percent occurred during responding to nonfire emergencies. Considering the time firefighters spend performing these duties, Kales found that the risk of a CHD-related death was up to 136 times higher during suppression, 14.1 times higher during alarm response, 10.5 times higher during alarm returning, and up to 6.6 times higher during physical training.

Looking at the statistics regarding firefighter mortality, it’s clear that heart disease and sudden cardiac death account for an overwhelming number of on-duty firefighter deaths, far eclipsing any other means. The literature on firefighters and heart disease seems to suggest that there is an inherent risk to being a firefighter and aggravating coronary heart disease. The stress of firefighting, shift life, and the body’s physiological response creates extended periods of tachycardia and other unusual patterns of heart load that aren’t found in a general population. There’s also something unique about the activity fire suppression that creates significant risk. The reason behind this extreme increase is currently unknown.

Departments and individuals can mitigate their risk of suffering a CHD-related death by reducing or eliminating their modifiable risk factors including smoking, obesity, high blood pressure, and high LDL cholesterol. Departments can encourage better nutrition through healthier meals and smaller portions, institute science-based and heart-healthy exercise regimens, and install stricter requirements on medical examinations and early screening for heart disease. Firefighting is an incredible profession for incredible people. If we work together, we can extinguish the risk of CHD.

(Photo by U.S. Air National Guard Airman 1st Class Cody Witsaman.)





References

Fahy RF, PR LeBlanc, JL Molis. “Firefighter fatalities in the United States in 2017.” NFPA Journal. July 2nd, 2018. Retrieved from www.nfpa.org/News-and-Research/Publications-and-media/NFPA-Journal/2018/July-August-2018/Features/Firefighter-Fatalities.

Barnard RJ and HW Duncan. “Heart rate and ECG responses of fire fighters.” Journal of Occupational Medicine. 1975 Apr;17(4):247-50. www.ncbi.nlm.nih.gov/pubmed/1127475.

Friel JK and M Stones. “Firefighters and heart disease.” American Journal of Public Health Aug. 1992. https://ajph.aphapublications.org/doi/10.2105/AJPH.82.8.1175-a.

Glueck CJ, W Kelley, P Want, et al. “Risk factors for coronary heart disease among firefighters in Cincinnati.” American Journal of Industrial Medicine. Sept. 1996. https://onlinelibrary.wiley.com/doi/abs/10.1002/ajim.4700300313.

Kales SN, ES Soteriades, SG Christoudias, et al. “Firefighters and on-duty deaths from coronary heart disease: a case control study”. Environmental Health. Vo 2, No. 14 (2003). https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-2-14.

Kales SN, ES Soteriades, CA Christophi, et al. “Emergency Duties and Deaths from Heart Disease among Firefighters in the United States”. N Engl J Med 2007; 356:1207-1215 DOI: 10.1056/NEJMoa060357 https://www.nejm.org/doi/full/10.1056/NEJMoa060357.





Aditya Shekhar is a research scientist, EMS educator, and writer. His articles about the physiologic progression of heart attacks have been read globally and won awards in the field of cardiology. He has taught Paramedic, EMT, EMR, and CPR courses in the United States and internationally and has designed online educational content for EMS providers.