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REVIEW ARTICLE
Cardiovascular Disease in US Firefighters
A Systematic Review
Elpidoforos S. Soteriades, MD,*† Denise L. Smith, PhD,‡§ Antonios J. Tsismenakis, MA,*¶储
Dorothee M. Baur, MD,*¶ and Stefanos N. Kales, MD, MPH*¶
Abstract: Cardiovascular disease (CVD) is the leading cause of on-duty death
among firefighters (45% of on-duty fatalities) and a major cause of morbidity.
CVD in the fire service also has adverse public safety implications as well as
significant cost impacts on government agencies. Over the last decade, our
understanding of CVD among firefighters has significantly improved and provides insight into potential preventive strategies. The physiology of cardiovascular arousal and other changes that occur in association with acute firefighting
activities have been well-characterized. However, despite the strenuous nature of
emergency duty, firefighters’ prevalence of low fitness, obesity, and other CVD
risk factors are high. Unique statistical approaches have documented that
on-duty CVD events do not occur at random in the fire service. They are more
frequent at certain times of day, certain periods of the year, and are overwhelmingly more frequent during strenuous duties compared with nonemergency
situations. Moreover, as expected on-duty CVD events occur almost exclusively
among susceptible firefighters with underlying CVD. These findings suggest that
preventive measures with proven benefits be applied aggressively to firefighters.
Furthermore, all fire departments should have entry-level medical evaluations,
institute periodic medical and fitness evaluations, and require rigorous return to
work evaluations after any significant illness. Finally, on the basis of the overwhelming evidence supporting markedly higher relative risks of on-duty death and disability among firefighters with established coronary heart disease, most firefighters with
clinically significant coronary heart disease should be restricted from participating in
strenuous emergency duties.
Key Words: CVD, risk factors, firefighters
(Cardiology in Review 2011;19: 202–215)
F
irefighting is widely recognized as a hazardous occupation. There
are more than 1 million Americans involved in this essential
public service. Most US firefighters are volunteers (72%), while
28% are career firefighters.1,2 On-duty fatalities in the US fire
From the *Department of Environmental Health, Environmental and Occupational
Medicine and Epidemiology (EOME), Harvard School of Public Health,
Boston, MA; †Department of Occupational and Environmental Medicine, Cyprus
Institute of Biomedical Sciences (CIBS), Nicosia, Cyprus; ‡Department of Health
and Exercise Sciences, Skidmore College, Saratoga Springs, NY; §University of
Illinois, Fire Service Institute, Champaign, IL; ¶The Cambridge Health Alliance,
Harvard Medical School, Employee Health and Industrial Medicine, Cambridge,
MA; and 㛳Boston University, School of Medicine, MA.
Supported by the Federal Emergency Management Agency (FEMA) Assistance to
Firefighters Grant (AFG) program. The studies described in this report were
conducted with support from awards EWM-2006-FP-01493 (PI: to S.N.K.),
EMW-2009-FP-00835 (PI: S.N.K.); EMW-2006-FP-02459 (PIs: to Dr. G.
Horn and D.L.S.), EMW-2007-FP-02581 (PI: Dr. P. Fehling), and EMW2009-FP-02044 (PI: to D.L.S.).
The authors declare that they have no financial or other conflict of interest with
respect to the current study.
Correspondence: Stefanos N. Kales, MD, MPH, Director, Employee Health & Industrial
Medicine, The Cambridge Health Alliance, 1493 Cambridge St, Macht 427, Cambridge, MA 02139. E-mail: [email protected] or [email protected].
Copyright © 2011 by Lippincott Williams & Wilkins
ISSN: 1061-5377/11/1904-0202
DOI: 10.1097/CRD.0b013e318215c105
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service are split roughly along the same proportions between volunteer and career members.2,3 Intuitively, one might think that most
on-duty deaths result from burns and smoke inhalation. However,
cardiovascular disease (CVD) is the single most frequent cause of
duty-related fatalities, accounting for almost half of all fatalities,
with 90% caused by coronary heart disease (CHD).4 Additionally,
for every fatal on-duty heart disease (HD) event, there are an
estimated 17 nonfatal, line-of-duty cardiovascular (CV) events in the
US fire service.5 Some major metropolitan fire departments experience as many as 12 to 20 chest pain or cardiac hospitalizations per
1000 person-years (1.5–2 cases/mo in roughly 1200 –1450 firefighters) 关personal communication兴. Given the team dynamic involved in AQ:1
firefighting, on-duty health events involve not only the affected team
member, but also potentially jeopardize the performance and safety
of coworkers. In addition, existing legislation often provides benefits
to firefighters who die in the line of duty, retire due to CV causes, or
simply develop a CV diagnosis.6,7 For example, in one major city,
the frequency of HD and hypertension workers compensation claims
in the fire department has ranged from 6% to 10% of all members
every year over 6 years 关personal communication兴. Thus, CVD
among firefighters is of importance to the fire service, the medical
community, and to society at large because of the considerable
financial and legal implications.
Physicians evaluating firefighters may face questions fairly
unique to this occupation. What determines whether an individual is
fit enough to safely join the fire service? Does the evidence support
aggressive management of firefighters’ CVD risk factors? What
determines whether a firefighter can safely return to emergency
duties after a CVD event? When is an HD event causally related to
the occupation of firefighting?
To better care for firefighters, this evidence-based review
discusses the hazards of firefighting and their associated CV strain,
the current prevalence and control of CVD risk factors among
firefighters, CVD epidemiology relative to firefighting, and recommendations for prevention and management of CVD. Because the
profession continues to be comprised predominantly of men, most of
the research conducted on firefighters and summarized here is from
male subjects.
OCCUPATIONAL HAZARDS, EXPOSURES, AND
STRESSORS
Firefighters are prone to certain behaviors, unique working
conditions, and hazardous exposures that may increase their CV
risks.8 In general, these can be divided into acute and chronic
stressors (Table 1).
T1
Chronic Stressors
Inadequate Physical Activity
Regular physical exercise of sufficient duration is widely
accepted to promote cardioprotection. However, infrequent and
inadequate amounts of physical activity are commonplace in the fire
service. Firefighters often experience long sedentary periods and
most departments do not mandate exercise, have regular exercise
Cardiology in Review • Volume 19, Number 4, July/August 2011
⬍DOI: 10.1097/CRD.0b013e318215c105⬎
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Cardiology in Review • Volume 19, Number 4, July/August 2011
TABLE 1. Potential Occupational Cardiovascular Hazards in
Firefighters
Chronic
Long sedentary periods
Smoke exposure
(gaseous and particulate)
Noise
Shift work/partial sleep deprivation
Fire house dietary patterns
Occupational stress
Post-traumatic stress disorders
High job demand and low decisional
control
Acute
Irregular physical exertion
Smoke exposure
(gaseous and particulate)
Noise
Excess heat/dehydration
Duty-specific hazards
Firefighting activities
Physical training
Alarm response
regimens, or require the maintenance of discrete physical fitness
parameters after hire. Furthermore, discretionary time for exercise
may be largely consumed by overtime and second jobs. Inadequate
physical activity makes firefighters prone to increased fat mass and
the metabolic syndrome. Moreover, obese firefighters are more
susceptible to further weight gain9 and associated decrements in
health.9,10 This is especially pertinent within the current obesity
epidemic, where recruits come from an increasingly heavy, less-fit
general public.11 While sedentary behavior promotes atherosclerosis
over the long-term, it also increases the risk of acute events.
Irregular bouts of strenuous activity in otherwise sedentary
individuals are a known precipitant of acute coronary events,12 as
are periods of high emotional stress.13 Indeed, firefighters are many
times more likely to experience CVD events during periods of high
psychological or physical stress, such as alarm response or fire
suppression/active firefighting.4 The concept of firefighting precipitating or “triggering” cardiac events is reviewed in the proceeding
discussion on strenuous duties.
Poor Dietary Habits
The unpredictable nature of emergency work leads to unreliable meal times, making the expediency of “fast-food” an unavoidable choice during certain work-shifts. In addition, working in shifts
makes career firefighters more likely to consume more meals with
higher fat and carbohydrate content.14 Shift workers have significantly increased triglyceride, free-fatty acid, and glucose levels and
lower mean HDL-cholesterol.15 Moreover “firehouse culture” is
known for recipes high in fat and dense in simple, refined carbohydrates. In one study, despite good awareness that dietary choices can
mitigate CV risk, 37% of the firefighters surveyed reported that they
enjoyed their current diets and had no desire to change.16
Shift Work
Career emergency responders commonly perform two 24hour shifts per week or rotating shifts, and growing evidence from
other occupations supports the association between shift work and
an increased risk of CVD.17–19 The mechanisms are likely multifactorial (psychosocial, behavioral, and direct physiological pathways) including altered dietary habits and sleep disruption favoring
metabolic syndrome, as well as less physical activity, higher stress
levels, and altered circadian rhythms.14,19 In addition to shift work,
second jobs and overtime details (commonly performed in between
regular fire shifts) can further contribute to chronic partial sleep
deprivation. Finally, sleep may also be affected by the psychological
stress of public safety work.20 Sleep disturbance or deprivation has
been associated with insulin resistance, weight gain, hypertension,
and CVD.21–28
© 2011 Lippincott Williams & Wilkins
Cardiovascular Disease in US Firefighters
Smoke Exposure
The exposure to smoke during firefighting work, consisting of
gases and particulates, was previously a more significant hazard and
therefore was considered an important contributor to on-duty
CVD.29 In recent decades, smoke exposure has been significantly
reduced by the mandated use of the self-contained breathing apparatus during fire attack and suppression (aka, “knockdown”) operations. However, firefighters often do not wear self-contained breathing apparatus or other respirators during “overhaul,” the period
immediately after fire suppression when the site is inspected for
remaining sources of potential reignition. During overhaul, various
noxious inhalants have been documented to still be present.30,31
Smoke inhalation can produce tissue hypoxia due to carbon monoxide, cyanide, and direct hypoxemia leading to myocardial ischemia in those with underlying CVD.32 Additionally, particulates
have been associated with autonomic dysfunction, including increased heart rate, decreased heart rate variability, and the promotion of arrhythmias.33–35
Although the long-term CV consequences of smoke exposure
in firefighters have not been adequately examined, plausible mechanisms for increased CVD related to chronic smoke exposure exist,
including the increased formation of free radicals, subsequent endothelial dysfunction, increased coagulability, and increased progression of atherosclerosis.36 Therefore, firefighters are strongly
encouraged to wear personal protective equipment during all activities with smoke exposure.
Noise
Noise is another intermittent exposure with negative CV
impact, primarily by increasing blood pressure.37 Alarms, sirens,
vehicle engines, and mechanized rescue equipment typically produce average noise exposures in the 63 to 85 dBA range. Personal
monitors have consistently documented intermittent exposures in
excess of 90 dBA (the federal permissible exposure limit for an
8-hour time-weighted average), and as high as 116 dBA.38 It has
been estimated that for each 5 decibel increase in acute occupational
noise exposure, there is a corresponding acute increase of 0.51 mm
Hg in systolic blood pressure.39 Thus, siren noises38,40 potentially
elevate systolic blood pressure by 5.9 to 11.8 mm Hg. There is
general agreement that the hemodynamic effects of intermittent
occupational noise persist during active exposure.41 However,
whether these pressor effects are longstanding42 or relatively shortlived43 has yet to be clearly elucidated.37
Psychological Stress
Firefighters are also exposed to a variety of psychological
stressors in the course of various emergencies, including fires,
natural disasters, terrorism, rescues, and the provision of emergency
medical services. High occupational demands, coupled with low
decisional latitude in Karasek’s classic “demand-control” model,
potentially contribute to increased stress levels, leading to elevated
heart rate and blood pressure, as well as poor sleep.44 Susceptible
firefighters exposed to more extreme stressors may develop posttraumatic stress disorder, associated with further adverse effects on
heart rate, blood pressure, and the metabolic syndrome.45– 47
Acute Cardiovascular Strain of Firefighting
Firefighting duties directly challenge the CV system, beginning with the alarm bell’s activation of the sympathetic nervous
system, the physical workload of firefighting, and associated heat
stress and dehydration (Fig. 1). Individual physiologic responses are F1
determined largely by the underlying medical status and cardiorespiratory fitness of each firefighter.
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basis of the relative risk of future health and employment outcomes.
Heat
FIGURE 1. Cardiovascular strain of firefighting.
Sympathetic Activation
Structural fires are chaotic, noisy, low-visibility work environments with severe time limitations, and life-threatening conditions promoting “fight or flight responses.” Thus, sympathetic activation is a crucial mediator of altered physiology during firefighting.
In one early study, researchers documented that firefighters achieved
maximally predicted heart rates during emergencies, including one
subject who sustained ⬎188 beats per minute for a 15-minute
period.48 Several groups have confirmed that heart rates increase
dramatically following the initial alarm and reach maximal or
near-maximal predicted values during simulated or actual fire emergencies.49 –51
Physical Workload
Structural firefighting includes forcible entry, search and
rescue, structure ventilation, and fire attack and suppression.
Such work requires high levels of both dynamic aerobic and static
physical exertion (climbing, crawling, squatting, moving and
lifting heavy items, and using heavy tools). Moreover, these
duties are performed wearing heavy, insulating personal protective equipment (PPE) often weighing in excess of 25 kg. Thus,
firefighting PPE adds to the metabolic and thermal demands of
firefighting. Studies of simulated firefighting tasks suggest that
the minimum aerobic capacity as measured by oxygen consumption (VO2) necessary to safely perform firefighting duties ranges
from 33.9 to 45 mL/kg/min (9.7–12.8 METS 关1 MET⫽ 3.5
mL/kg/min兴).52–55
A recent study measured oxygen consumption during a
series of simulated firefighting tasks at a self-selected pace and
found that firefighters averaged 62% of their VO2max (29 mL/
kg/min) over 8.5 minutes.52 At the end of the activity, oxygen
consumption averaged 31.5 mL/kg/min, but ranged widely (12.5–
53.1 mL/kg/min), with a significant inverse correlation between
VO2 max and performance time. Thus, fitter firefighters safely
completed the tasks in less time. Among a carefully selected
sample of firefighters, 100% of subjects with a VO2 max ⬍34
mL/kg/min (9.7 METS) failed a standard firefighting physical
abilities test (PAT).56 The National Fire Protection Association
(NFPA) has suggested 12 METS (approximately 42 mL/Kg/min
VO2) as the minimum exercise capacity required for the safe
performance of firefighting.57 A recent cohort study of professionally active career firefighters found more than one-third have
aerobic capacities ⱕ12 METS.58 Longitudinal studies have been
initiated to objectively determine “safe” fitness levels on the
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Firefighters produce large amounts of metabolic heat while
working, and insulating PPE severely limits heat dissipation. Furthermore, fire-related heat contributes to additional thermal strain.
Most studies of firefighting effects on core temperature have used
relatively short bouts (18 –38 minutes) of activity in training
fires.59 – 61 These data suggest that core temperatures increase at a
rate of approximately 0.05°C/min or 1.0°C over 20 minutes of acute
firefighting activities. This degree of hyperthermia increases CV
strain. During longer fire operations, this rate of core temperature
increase can produce serious heat-related injuries and/or illness.
Several factors predispose to heat illness, including obesity,
low levels of physical fitness, dehydration, lack of acclimatization,
previous history of heat illness, and sleep deprivation.62 Furthermore, medical conditions such as diabetes, sweat gland dysfunction,
viral illness, diarrhea, sunburn, and cardiac disease as well as
medications that impair thermoregulation, including stimulants, anticholinergic, and certain CV drugs further increase the risk.62,63
Dehydration
Dehydration is closely related to heat stress and decreases
plasma volume, further impairing thermoregulation and resulting in
hemoconcentration. Because of encapsulating PPE, firefighters often
sweat profusely, as much as 1.2 to 1.9 L/h during strenuous firefighting activity.49,59,64 Smith et al49 reported a 15% reduction in
plasma volume after 3 bouts of strenuous firefighting activity that
can have significant physiologic impacts, such as decreased stroke
volume. In a series of three, 7-minute training drills with live fires,
stroke volume decreased to almost 20% below baseline by the end
of the trial, despite a 10-minute break to cool down and ingest fluids
between the second and third bout of firefighting.49 Of particular
concern with regard to dehydration are several fire service reports
suggesting that firefighters are often relatively dehydrated even
before they begin firefighting activity.65– 68
Dehydration also leads to hemoconcentration associated with
an increase in the concentration of several biochemical parameters.49 Firefighting is also associated with approximately 25% increase in circulation platelet numbers and activity likely attributable
to hemoconcentration and increased sympathetic nervous activity
along with an increase in several coagulatory variables.65,69 Thus,
firefighting has the potential to acutely increase prothrombotic
tendencies, which is potentially important for firefighters with underlying vascular disease.
In summary, firefighting activity leads to hyperthermia, dehydration, and considerable CV strain. In a susceptible individual,
the CV strain associated with firefighting activity may trigger a
sudden cardiac event through several biologically plausible pathways: increased sheer stress may cause rupture of vulnerable plaque,
hypercoagulability may lead to platelet aggregation and clot formation, or the increase in myocardial oxygen demand associated with
firefighting may exceed myocardial oxygen supply.
STANDARD CVD RISK FACTORS AMONG
FIREFIGHTERS
On-duty CVD events and premature retirements related to
HD occur almost exclusively among susceptible firefighters with
underlying CVD (whether overt and previously diagnosed or theretofore, unrecognized and “subclinical”). Accordingly, firefighters
suffering adverse CV-related job events have been shown to have an
excess of discrete CVD risk factors compared with control firefighters (Table 2).6,70,71
T2
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TABLE 2. Relative Risk of Cardiovascular Outcome by Risk
Factor
On-Duty
CHD
Fatalities69
Current smoking
8.6 (4.2–17)
Hypertension
12 (5.8–25)
Obesity, BMI ⱖ30
3.1 (1.5–6.6)
Cholesterol ⱖ5.18
4.4 (1.5–13)
mmol/L (200 mg/dL)
Diabetes mellitus
10.2 (3.7–28)
Prior diagnosis
35 (9.5–128)
of CHD
Age ⱖ45-yr-old
18 (8.5–40)
Non-CHD
Cardiovascular
CHD
Retirements
Retirements
OR (95% CI)6 OR (95% CI)6
2.5 (1.2–5.1)
11 (6.1–20)
3.6 (2.0–6.4)
1.1 (0.51–2.24)
3.9 (2.5–6.2)
5.4 (3.7–7.9)
1.4 (0.96–1.93)
2.4 (1.6–3.6)
7.7 (2.9–20)
NA
13 (6.1–28)
30 (9.1–96)
26 (13–51)
63 (35–111)
CHD indicates coronary heart disease.
Smoking
Smoking is a major risk factor for CVD. Not surprisingly,
some US States have passed legislation prohibiting firefighters hired
subsequent to the passage of these laws from smoking tobacco.72
However, smoking continues to be a problem in the fire service, both
among veteran firefighters “grandfathered” out of smoking prohibitions, in jurisdictions without such restrictions, and among volunteers. The prevalence of current smoking in recent firefighter studies
ranges from 10% to 18% among general cohorts, whereas the
prevalence is 40% to 50% among those succumbing to on-duty CHD
fatalities.70,71,73 Thus, smoking has been demonstrated to be a
strong independent risk factor for on-duty CHD events, CHD-related
retirements, and for CHD event case-fatality among firefighters
(Table 2).
Hypertension
Hypertension is universally accepted as a major risk factor for
CVD, with increasing risk starting in the prehypertensive
range.74 –76 Approximately, 50% of firefighters have prehypertension, and 20% to 30% are hypertensive, a proportion expected to
increase due to the obesity epidemic.37,77 Hypertension is also
inadequately controlled in these professionals. In a prospective
investigation, almost 75% of firefighters with hypertension
lacked adequate blood pressure control,78 similar to the general
population.79 – 81 Moreover, in the absence of criteria requiring
proactive blood pressure management, the control of hypertension did not improve over the course of 4-year follow-up.78 In the
above career firefighter cohort,78 2% to 5% had stage 2 hypertension, whereas surveys of volunteer firefighters have found 4%
to 9% with stage 2 blood pressure readings.82
Higher blood pressures have been associated with CVD risk
factor clustering, including older age, dyslipidemia, insulin resistance, and glucose intolerance.9,10,83– 85 Hence, total aggregate CHD
risk is greater among hypertensive firefighters than would be expected based upon the blood pressure alone. Accordingly, hypertension is an independent predictor of adverse employment outcomes:
disability retirements due to HD, incident CHD, nonfatal myocardial
infarction, and on-duty CHD fatalities (Table 2).6,71,83– 88
Evidence suggests that hypertension-associated risks are concentrated among individuals with uncontrolled, rather than controlled, hypertension. A roughly 3-fold increase in adverse job
outcomes with hypertension (combined outcome including on-duty
death, injured on-duty, termination of duty, resignation, premature
retirement, incident CV event) was attributable largely to firefighters
with stage 2 hypertension who were not taking antihypertensive
© 2011 Lippincott Williams & Wilkins
Cardiovascular Disease in US Firefighters
medications.83 Likewise, among on-duty CHD fatalities, left ventricular hypertrophy and/or cardiomegaly were found in 56% of
firefighters who had undergone an autopsy, suggesting chronically
uncontrolled hypertension.70 In Massachusetts, chronically uncontrolled hypertension and hypertensive HD were responsible for 8%
of CV disability retirements, representing a third of CV pensions
awarded to firefighters for non-CHD causes.6 Nonetheless, similar to
the general population, the majority of incident CVD events that
occur among emergency responders occur in persons who are
initially prehypertensive or only mildly hypertensive with average
pressures in the range of 140 to 146/88 to 92 mm Hg.37
Obesity
Obesity is another well-established CVD risk factor, associated with cardiometabolic risk factor clustering.9 –11 Obesity and
increased body mass index (BMI) are also risk factors for job-related
disability,89 incident CHD,86 on-duty CHD events,70 and CVD
retirements6 (Table 2). However, the prevalence of obesity among
firefighters has been increasing steadily over time within the overall
obesity epidemic, so that roughly 40% of firefighters are now
obese.9,10 In the 1980s and early 1990s, the average veteran had a
BMI of 25.4 to 26.7 kg/m2,86,90 but by 1996 –1997, mean BMI had
increased to almost 29 kg/m2,10,91 and by 2001, it was 29.7 kg/m2.9
Today, even much younger firefighter recruits (mean age, 26 years)
have an average BMI of 28.5 kg/m2 (Fig. 2).11 A recent population- F2
based investigation of career and volunteer firefighters— using BMI,
waist circumference, and body fat measures—proved that the high
obesity prevalence was not due to the misclassification of increased
muscle mass.92 Contrary to common wisdom in the fire service,
obesity was even more prevalent when assessed by body fat rather
than BMI, and the misclassification of muscular firefighters as obese
by BMI was infrequent.
Among emergency responder recruits, 44% were overweight
and 33% were obese, and in this cross-sectional study, obese
subjects had an almost 7-fold greater risk of hypertensive blood
pressure readings as compared with normal weight subjects (16% vs.
2.4%).11 Another recent study of young firefighters (29.7 ⫾ 8.0
years), that excluded hypertensive subjects, showed similar results
regarding the prevalence of overweight and obesity.77 Additionally,
central and peripheral blood pressure were higher, while aortic and
carotid artery stiffness were increased in those firefighters in the top
tertile of BMI.77 Finally, with obesity prevalence among firefighters
ranging from 30% to 40% and more than 90% of them being male,
significant number of obese responders have or are expected to
develop obstructive sleep apnea,93 another risk factor for hypertension, CHD, and increased mortality.94
Dyslipidemia
Dyslipidemia is another prevalent risk factor among firefighters, although their mean total cholesterol levels decrease over time
from values of 200 to 220 mg/dL to 180 to 200 mg/dL, perhaps
because of more frequent statin use.82,95 The prevalence of low
HDL (⬍40 mg/dL) has been found to be 26% to 31%, whereas high
fasting triglycerides (ⱖ150 mg/dL) have been found in more than
20% of firefighters.95,96 The assessment of lipid abnormalities as an
independent risk factor in retrospective studies of on-duty CHD
events and CHD-related retirements has been limited because many
of the firefighters suffering from these events lacked premorbid lipid
values for comparison. Nonetheless, in unadjusted analyses, high
total cholesterol (ⱖ200 mg/dL) is associated with a 2.4-fold and
4.4-fold increased risk of CHD retirement and on-duty CHD death,
respectively.6,71 Likewise, in a prospective study, firefighters who
developed CHD had significantly higher total cholesterol, LDL, and
triglycerides.86
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FIGURE 2. Mean BMI in different
age groups from all representative
firefighter studies: 1980 –2005.
Diabetes Mellitus
The frequency of hyperglycemia (fasting glucose ⱖ110 mg/
dL) in firefighters may be as low as 1%,96 while others have found
the prevalence of type II diabetes mellitus (DM 2) to be 3% to
4%.71,97 As expected, the prevalence of DM 2 among firefighters
succumbing to on-duty CHD events and CHD retirements is much
higher: 21% and 26%, respectively. DM 2 is associated with an
unadjusted 10- to 13-fold increased risk of on-duty CHD death or
CHD retirement (Table 2).6,71 However, after multivariate adjustment, DM 2 is not a significant independent predictor in retrospective studies. Thus, DM 2-associated risks are likely mediated
through concurrent effects on blood pressure, lipid metabolism, and
previously established atherosclerotic disease.
Established CHD and CHD Equivalents
Peripheral artery disease, carotid stenosis, and history of
thrombotic stroke or transient ischemic attack, diagnosed before a
subsequent on-duty event or later retirement, are considered together
for risk assessment purposes. The prevalence of established CHD is
as low as 1% among career firefighters,71 but as high as 9% among
volunteers.97 However, among firefighters experiencing fatal and
nonfatal on-duty CHD events, previously diagnosed CHD accounts
for 31% and 18% of cases, respectively,70 and is a strong independent risk factor for subsequent on-duty CHD events, on-duty CHD
case-fatality, and CHD-related retirements (Table 2).6,70,71 Preexisting evidence of myocardial damage due to past infarction is
associated with a roughly 2-fold increased risk of case fatality (ie,
whether an on-duty event results in death or nonfatal disability).70
FIGURE 3. Age and risk of on-duty CHD death in US firefighters. Reprinted with permission from N Engl J Med.4
risk. Conversely, relatively few departments require periodic testing
of veterans, and even when they do, they usually do not require
stringent physical fitness requirements for maintaining active duty.
Age
OCCUPATIONAL EPIDEMIOLOGY OF CVD IN THE
FIRE SERVICE
Firefighting and the Lifetime Risk of CVD
Increasing age is a robust, independent predictor of adverse
CVD outcomes in firefighters, even after multivariate adjustment for
all other risk factors (Table 2) and adjustment for types of duty
performed, during or just prior to the onset of the CHD event
(Fig. 3).4 Although the relationship of age to CVD and mortality is
obvious, it deserves emphasis, because most current preventive and
selective efforts in the fire service consist of medical and physical
abilities standards required of young recruits at the lowest relative
A classic methodology for evaluating the occupational risks
of certain diseases is to compare the morbidity and/or mortality
attributable to said disease(s) in a particular occupation to that found
in the general population or a comparable occupational cohort free
of the exposures/risks expected in the index profession. Although
“presumed” by the fire service and by many legal jurisdictions (see
legal issues below) that firefighters have an elevated lifetime risk of
CVD, the evidence is inconclusive and does not, on balance, support
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Cardiovascular Disease in US Firefighters
TABLE 3. Duty Specific Risks of Heart Disease
Type of Duty
Kales et al71 (Relative Risk of
CHD Death)
Holder et al6 (Relative Risk of
Heart Event Leading to Retirement)
Kales et al4 (Relative Risk of
CHD Death)
64.1 (7.4–556)
7.6 (1.8–31.3)
5.6 (1.1–28.8)
3.4 (0.8–14.7)
1.7 (0.5–5.9)
51 (12–223)
0.68 (0.2–2.7)
6.4 (2.5–17)
0.37 (0.07–1.8)
0.75 (0.3–1.8)
53 (40–72)
5.2 (3.6–7.5)
7.4 (5.1–11)
5.8 (4.1–8.1)
1.3 (0.9–2.0)
1.0
1.0
1.0
Fire suppression—OR (95% CI)
Physical training—OR (95% CI)
Alarm response—OR (95% CI)
Alarm return—OR (95% CI)
EMS and other non-fire emergencies—
OR (95% CI)
Firehouse and other non-fire emergencies—
OR (95% CI)
CHD indicates coronary heart disease; EMS, emergency medical service; OR, odds ratio; CI, confidence interval.
such a hypothesis. Similar to the general population, CVD accounts
for about 35% of firefighters’ lifetime mortality.98 –105
These cohort mortality studies of firefighters have failed to
demonstrate any consistent increased risk of CVD death: firefighters’ standardized mortality ratio for CHD is approximately 0.9 or
10% lower when compared with that of the general population.106 It
has been argued that these “negative” findings are likely because of
the “healthy worker effect”. In other words, based on medical and
physical abilities selection criteria that must be passed to join the fire
service, as well as the health benefits of being occupationally active,
firefighters are expected to enjoy greater wellbeing. Therefore, they
have a lower risk of morbidity and mortality than the general
population, which includes individuals not occupationally active,
and those with significant infirmities and disabilities.105–107
Proportionate On-Duty CVD Mortality
Proportionate on-duty CVD mortality refers to the proportion
or percentage of deaths attributable to CV etiologies occurring while
on-duty. There is unanimous agreement that firefighters experience
the highest proportionate mortality due to CVD while on-duty as
compared with other occupational groups and other public safety
officers.71,108 CVD accounts for about 45% of about 100 on-duty
deaths per year among firefighters, whereas the corresponding figures for police officers, construction workers, emergency medical
services workers, and all occupations combined have been reported
as 22%, 12%, 11%, and 15%, respectively.4,109,110 Presumably,
these findings are explained by the unique interaction of firefighters’
risk profiles and the exposures and stressors encountered during
specific types of firefighting duties. Not surprisingly, the risks of
on-duty CHD events vary widely across different duties, with the
highest risks associated with the most strenuous tasks (see strenuous
duties and Table 3).
Strenuous Firefighting Duties as a Trigger of CVD
Events
Numerous studies have documented that various types of
strenuous situations can trigger acute CV events in individuals with
underlying disease including: exercise,12 snow shoveling,111 episodes of anger, and watching sports events.13,112 Similarly, environmental insults such as surges in air pollution35 or influenza
activity113 precede spikes in CVD events, which are largely confined
to susceptible persons within the larger exposed population.
Along these lines, 3 independent studies have provided compelling evidence that certain strenuous firefighting duties can precipitate CVD events in susceptible firefighters.4,6,71 Together, they
show remarkably similar odds for CVD events during specific fire
service duties relative to nonemergency duty when the same assumptions are made for the average professional time spent in each
type of duty (Table 3). In the largest of the studies, covering all 449
© 2011 Lippincott Williams & Wilkins
on-duty CHD deaths among US firefighters during 1994 –2004, 3
different risk estimates were calculated to account for uncertainties
in the relative times spent by firefighters across different duties.
Regardless of the model applied, the risks of CHD death remained
markedly elevated in a significant manner for the same strenuous
duties. For example, although fire suppression (mitigating and extinguishing fires) represents only about 1% to 5% of annual professional time among firefighters, fire suppression accounts for ⬎30%
of on-duty CHD deaths or a relative risk of roughly 10 to 100 times
higher than that of nonemergency duties depending on the risk
estimate used.4 Notably, fire suppression/firefighting is much more
likely to precipitate a CHD event than exercise alone.
Circadian and Seasonal On-Duty CHD Patterns
Complementary evidence supporting that emergency duties
can precipitate CVD fatalities comes from the circadian distribution
of on-duty CHD deaths in firefighters,71 which mirrors the distribution of emergency alarms and dispatches, as well as that of fire
service trauma deaths. Rather than following the typical circadian
pattern seen in the general population, 67% to 77% of on-duty CHD
deaths among firefighters occur between noon and midnight as do
F4
most emergency operations (Fig. 4).71
Regarding the seasonal pattern of on-duty CHD deaths, there is
a winter peak with a smaller secondary peak in summer (Fig. 5).114 F5
Seasonal effects could not be explained by day-to-day temperature
fluctuations in the single seasonal study reported to date. However,
the smaller summer excess of mortality was mostly due to a higher
number of fire suppression deaths, making additional heat stress one
plausible hypothesis. The winter peak may be produced in part by
typical chronobiological changes observed during colder weather
months, including increases in plasma viscosity, serum lipids, coagulation factors, and blood pressure, all of which are prothrombotic.115,116 Second, surges in influenza and upper respiratory infections typically occur in the first quarter of the year and have been
associated with spikes in CHD incidence.113
MANAGEMENT OF CVD RISK IN THE FIRE SERVICE
The prevention and management of CVD risk among firefighters should include pre-placement medical examinations and
PAT for new recruits. Additionally, continuing members should
have periodic medical exams, PAT fitness and wellness programs,
and “return to work” or “fitness for duty” evaluations.
Pre-placement Medical Examinations
Pre-placement medical examinations should be a part of the
hiring process to review baseline health status, identify those requiring additional medical testing to rule out conditions possibly affecting job performance, and exclude those who are unable to safely
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FIGURE 4. Circadian distribution of on-duty CHD deaths in firefighters versus the daily pattern of emergency calls 关EC兴 (A)
and versus the circadian pattern in the general population (B). Reprinted from Environ Health.71
perform the essential job duties. The National Fire Protection
Agency (NFPA) (a private entity, which cannot mandate standards,
but convenes committees of national experts to create consensus
standards) as well as various government agencies have promulgated standards for pre-placement medical exams. In general, these
standards specify minimum examination components and medical
conditions that either lead to exclusion from a fire department or
lead to exclusion under various circumstances or degrees of severity.57,117,118 With respect to CVD risk factors, the pre-placement
medical examination should ideally include an assessment of habits
(eg, tobacco use, diet, sleep hygiene, and exercise), anthropometric
measures (BMI, waist circumference, body composition, that is,
208 | www.cardiologyinreview.com
body fat estimates), blood pressure, lipids and glucose, resting ECG,
as well as an objective measure of cardiorespiratory fitness (ie, a
treadmill, stair climbing, bicycle ergometer, or similar test).
Physical Abilities Testing
PAT is a type of “functional capacity testing” that attempts to
simulate the physical requirements of essential firefighting duties.
Generally, it must be completed according to a fixed protocol within
specific time limits on a standardized course or environment. The
candidate PAT, which is endorsed by major Fire Service organizations, has been reported to elicit approximately 73% of maximal
oxygen uptake and 90% of maximal heart rate in a group of
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FIGURE 5. Seasonal Distribution of US firefighters’ CHD
deaths. Reprinted from Chronobiol Int.114
individuals who successfully completed the test within the allotted
time, and who were thought to be representative of incumbent
firefighters.119 These authors also reported that maximal aerobic
power, body mass, and handgrip strength accounted for 67% of the
variance in completion time on the candidate PAT, although they
noted large individual variations in estimations of time to completion. Like the pre-placement examination, PAT components and
requirements are usually predetermined by a governmental entity or
recommended by private groups that have convened expert panels.120,121 It should be conducted on candidate firefighters and
veteran firefighters who have successfully completed all required
medical evaluations and do not possess exclusionary conditions. It
should never be used in the absence of a fire department medical
examination to determine medical clearance.71 Any doubts about a
firefighter’s fitness to safely engage in a PAT should be ruled out by
a medically supervised exercise test.
Fitness and Wellness Programs
Fitness and wellness programs provide the opportunity for a
broad array of preventive strategies.122–129 These programs should
focus on the triad of healthy diet, regular and frequent exercise, and
good sleep hygiene. A comprehensive wellness program will also
provide educational programs and employee assistance options.
Robust evidence supports the benefits of diets lower in saturated
fats, salt, and refined carbohydrates; and higher in unsaturated fats,
fiber, and fruits. Several studies are underway to evaluate firefighters’ eating habits, barriers to healthier diet options, and ways to
facilitate better dietary choices.
Another vital component of an effective wellness program for
firefighters is regular and frequent exercise that emphasizes vigorous
aerobic exercise while including some strength training. The goals
of the fitness program should be the following: (1) optimizing work
performance, (2) improving safety, (3) promoting and maintaining
higher levels of cardiorespiratory fitness, and (4) exerting beneficial
effects on modifiable CVD risk factors. Given that most of current
firefighters are overweight and one-third to 40% are obese, large
gains in health and fitness may be realized from exercise programs,
especially when coupled with healthy diets. Promoting improved
sleep hygiene can have complimentary beneficial effects in preventing or improving the metabolic syndrome and lowering stress levels
among firefighters. Additionally, normal sleep duration (7– 8 hours
per night) is associated with a lower incidence of obesity, diabetes,
hypertension, myocardial infarction, stroke, and all-cause mortality
© 2011 Lippincott Williams & Wilkins
Cardiovascular Disease in US Firefighters
when compared with so-called short sleep or chronic partial sleep
deprivation (sleeping ⬍5– 6 hours per night).130 –134
Additional wellness measures should address tobacco use
and influenza vaccination. Smoking or tobacco use should be
prohibited among new hires and strong incentives along with
specific programs on smoking cessation should be offered to
incumbent firefighters who continue to smoke. Given firefighters’
close contact with the public while providing emergency medical
services and that a relative excess of CHD deaths among firefighters occurs during the winter, annual influenza vaccinations
should be strongly encouraged.
The firefighter wellness intervention trial called PHLAME
(Promoting Healthy Lifestyles: Alternative Models’ Effects) is a
prospective randomized controlled study that has examined both
individual (one-on-one motivational counseling) and team approaches to health promotion. Both individual- and team-based
interventions had positive effects on LDL cholesterol reduction and
personal exercise habits, compared with controls.135 Additionally, at
1 year, both interventional groups improved weight control, significantly increased fruit and vegetable consumption and had a greater
sense of well-being compared with controls.136 Although follow-up
at 4 years showed some dissipation of the effects of the year-long
interventions, dietary and exercise behaviors remained improved, on
the whole, compared with baseline.137 Interestingly, even control
groups showed improved health and dietary behaviors at follow-up,
suggesting the dissemination of information on healthy behaviors
from firefighters in the experimental groups to colleagues in the
control groups.
Periodic Medical Examinations
Periodic medical examinations objectively assess risk factor
profiles and are likely to identify firefighters in need of risk reduction before overt problems occur. Periodic examinations can also
recognize firefighters who may need additional medical testing and
may identify firefighters unable to safely perform the essential job
duties of a firefighter so that they can be restricted from strenuous
duties. Again, standards for such examinations have been recommended by the NFPA and government agencies in certain jurisdictions; and components should be similar to those of pre-placement
examinations.
The sections above illustrate that hypertension, obesity, and
dyslipidemia are inadequately managed among firefighters in the
sense that large proportions of firefighters have risk-factor measurements that fall outside of evidence-based healthy and/or target
ranges. Given firefighters’ occupational hazards for CVD, physicians should be more proactive when providing care to firefighters.
It is also important to emphasize that periodical medical evaluations
be provided to both career and volunteer firefighters.
Lipids
In general, lipids should be managed according to ATP
criteria.138 No evidence from firefighters or similar occupational
groups directly support high sensitivity C-reactive protein as a necessary adjunct to serum lipids in periodic exams, however, data from
middle-aged and older adults in the general public suggest that it could
be useful in identifying additional firefighters who despite low LDL
values may benefit from primary prevention with statins.139,140
Blood Pressure
Blood pressure should be assessed and managed according to
Joint National Committee guidelines.37,74 Unfortunately, the NFPA
and some jurisdictions have suggested that blood pressures of up to
160 to 180/100 are acceptable for active duty.57,117,118 Outdated
occupational blood pressure standards unintentionally encourage
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TABLE 4. Blood Pressure Management Scheme for Emergency Responders*†
Blood Pressure
Fitness Determination
Recommended Intervention(s)
Occupational Follow-up
Normal
Unrestricted duty
Population-based wellness programs
Pre-hypertension
Unrestricted duty
Stage 1
Hypertension
Time-limited clearance for duty
Population-based wellness programs
Individual education§
Population-based wellness programs
Individual education§
Hypertension treatment & evaluation,
including appropriate tests to rule out endorgan damage
Stage 2
Hypertension
Restricted to modified duty (excluding
physical exertion related duties)
until blood pressure reaches Stage 1
or lower
Population-based wellness programs
Individual education§
Clinical management of Hypertension and
evaluations for end-organ damage, including
echocardiogram
12–24 mo based on overall CVD risk
factor profile‡
6–12 mo based on overall CVD risk
factor profile‡
Time-limited clearance (6–12 mo)
based on overall CVD risk factor
profile‡
Expect controlled blood pressure at
follow-up
If blood pressure control improves,
revert to annual follow-up
Time-limited clearance after adequate
blood pressure control
Follow steps for Stage 1, as above
*Assumes absence of comorbid conditions potentially affecting fitness for duty, prognosis, and treatment decisions.
†
Adapted from Am J Hypertens.37
‡
Full CVD risk factor assessment, including tobacco use, fasting lipid profile, blood glucose level, etc.
§
DASH: Dietary Approaches to Stop Hypertension,3 and other non-pharmacologic measures.
CVD indicates cardiovascular disease.
firefighters to believe that elevated blood pressures are acceptable.
Accordingly, a state of the art scheme for evaluating and managing
emergency responders’ blood pressure within the Joint National
Committee framework has been proposed (Table 4).37 Briefly,
responders with stage 2 blood pressure (ⱖ160/100 mm Hg) should
be restricted from strenuous duties until better control is achieved and
investigations for end-organ damage, including an echocardiogram to
rule out left ventricular hypertrophy should be completed. Firefighters
with stage 1 hypertension (140 –159/90 –99 mm Hg), should be given
time-limited work clearances similar to corresponding rules for federally-regulated drivers,141 with work status and follow-up intervals
depending on the achievement of improved blood pressure control at
re-evaluation. Based on the chronicity of the elevated blood pressure in
those with stage 1 hypertension and clinical judgment, an echocardiogram should be considered to evaluate possible left ventricular hypertrophy. Appropriate evaluations for left ventricular hypertrophy should
also be done in firefighters with exaggerated blood pressure responses
to exercise.
Obesity
Despite the robust evidence of obesity’s negative effects,
currently there are no occupational guidelines for obesity as a
limiting condition for active duty among firefighters. Physicians
should objectively assess weight status with BMI, waist circumference, and body fat measures. Because many firefighters have erroneous perceptions of their weight and have not been appropriately
informed by physicians that they are carrying excess weight, overweight and obese firefighters should be given weight loss guidance
based on exercise, diet, and sleep hygiene as first-line measures.142,143 Furthermore, we propose that firefighters with stage III
obesity (BMI ⱖ40) be restricted from strenuous duty until they have
lost weight and improved their fitness status.
Aspirin
Following current guidelines, male firefighters aged ⬎45
years should consider taking low dose acetylsalicyclic acid (ie, 81
mg/d) as primary prevention.144 Aspirin has a strong antiplatelet
effect under resting conditions, but does not attenuate increased
platelet function occurring with exercise.145,146 Therefore, the pre210 | www.cardiologyinreview.com
cise benefits of aspirin for firefighters are unknown. Studies in
firefighters are underway to clarify the ability of acetylsalicyclic acid
to block several prothrombotic alterations in blood parameters that
have been observed during acute firefighting activities.
Exercise Testing
Further prognostic risk stratification of all asymptomatic
firefighters without a history of atherosclerotic disease should include maximal exercise tolerance testing (ETT) starting at the age of
45 and earlier35– 40 in firefighters with known CVD risk factors,
depending on the risk profile. ETT results should be examined for
electrocardiogram changes suggestive of ischemia, for blood pressure response, heart rate recovery, and exercise capacity.147 These
results can then be interpreted using integrated risk tools such as the
Duke treadmill score.148 We hypothesize that as in the general
population, aerobic capacity or cardiorespiratory fitness will
predict morbidity and mortality, with each additional MET
achieved conveying additional benefit. The NFPA has suggested
12 METS as the minimum capacity required for safe firefighting.
Prospective studies of asymptomatic firefighters are underway to
better define ETT criteria.
If ETT are performed on asymptomatic individuals, most
abnormal findings will ultimately be judged as “false positives.”
Traditionally, firefighters with abnormal ETT have been evaluated
further by myocardial perfusion imaging or stress echocardiograms.
Roughly, 30% remain abnormal on the follow-up test and require
invasive angiography, but only 26% of abnormal perfusion studies
(8% of all abnormal ETTs) have angiogram findings of ⱖ50%
stenosis of a coronary artery.149 In the Los Angeles County Fire
Department, a more cost-effective protocol has been developed
using coronary artery calcium scores as a “gate-keeper” test for
asymptomatic firefighters with abnormal maximal treadmill tests as
defined as ⱖ1 mm of ST depression. This is followed by a noninvasive computed tomography (CT) angiogram as the next study for
those with high calcium scores. Finally, invasive angiogram is
recommended only for those with an abnormal CT angiogram, with
ⱖ50% stenosis being confirmed 95% of the time.149 We do not
recommend coronary artery calcium scores or CT angiograms as
routine tests at this time for all firefighters, although some medical
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centers are promoting and marketing these tests as “screens” to the
fire service.
Fitness for Duty /Return to Work Evaluations
Fitness for duty or return to work evaluations are extremely
useful in the risk assessment and characterization of firefighters who
have developed overt CVD, and may no longer qualify for strenuous
activities. Because many fire departments do not permit modified
duty, physicians should verify with the fire department any claims
by firefighters that their duties are not strenuous or somehow are
limited to certain activities. On the basis of overwhelming evidence
supporting higher relative risks of on-duty death and disability
among firefighters with a history of CHD (Table 2), most firefighters
with known CHD or CHD equivalents (previous thrombotic strokes,
transient ischemic attacks, carotid stenosis, or symptomatic peripheral arterial disease) should be restricted from participating in
strenuous emergency duties. Current evidence suggests that if firefighters with known clinically significant atherosclerotic disease
were restricted from emergencies, such a measure would likely lead
to a decrease of about 30% in on-duty CV mortality in the fire
service, given that these cases currently account for 31% of on-duty
fatalities.70 However, certain select individuals who are asymptom-
TABLE 5. NFPA Guidelines for Veteran Firefighters for
Return to Work in the Presence of CHD
No angina
No stenosis of major coronary artery (⬎70% of lumen)
Normal LVEF
Exercise tolerance ⬎12 METS during EST
No exercise induced angina
No ischemia or arrhythmias during EST (with imaging)
No persistence of modifiable risk factor for plaque rupture (tobacco, HBP,
cholesterol ⬎180, LDL ⬎100, HbA1c ⬎7)
Data from Hales T. N Engl Coll Occup Environ Med (NECOEM) Reporter 2008;
2(24). Available at: http://www.necoem.org/documents/v2_24.pdf.150
CHD indicates coronary heart disease; LVEF, left ventricular ejection fraction;
METS, metabolic equivalents; EST, exercise stress test; HBP, high blood pressure;
LDL, low density lipoprotein; HbA1c, glycated hemoglobin.
Cardiovascular Disease in US Firefighters
atic, have excellent exercise capacity, no myocardial damage, and
are found with very early evidence of CHD as a result of screening
may be able to safely continue performing firefighting duty. The
NFPA has suggested criteria for evaluating safe return to work in the
presence of CHD (Table 5).150 However, their criteria have not been T5
validated by prospective or retrospective studies, and clinicians
should bear in mind that prior atherosclerotic disease independently
predicted case-fatality, and that death was more common in those
who had returned to service with prior evidence of myocardial
damage from earlier infarction(s).70
MEDICOLEGAL ISSUES
Because firefighters are generally government employees and
provide public services, CVD among firefighters represents an
important public health/policy problem with death, disability, and
retirement benefits typically regulated by specific legislation. In
particular, special legislative provisions often legally “presume”
CVD among firefighters to be work-related regardless of the presence of standard CVD risk factors. More than 35 states have
“presumptive” laws entitling firefighters with HD to receive publicly
funded disability and/or death benefits.6,120,121 In general, this type
of benefit legislation creates the legal presumption that the firefighters’ disease is causally related to firefighting even in the presence of
other obvious disease risk factors. The Hometown Heroes Survivor
Benefits Act provides federal aid to the families of firefighters,
police officers, and EMS workers who die of on-duty heart attacks
or stroke.7 Given that society has decided to fund such benefits, both
the fire service and taxpayers would be better served if a portion of
these resources were invested proactively in prevention programs to
reduce firefighters’ CVD morbidity and mortality, as well as generate downstream cost-savings. This recommendation is especially
important given that resources devoted to prevention programs for
many fire departments are either nonexistent or scarce at best.
In jurisdictions lacking strong legal presumptions, several
studies (Table 3) provide a stronger basis for making determinations
of work-relatedness. The findings in Table 3 support previous
suggestions by Guidotti104 that events occurring during or within a
day of strenuous duties, such as fighting a fire, responding to or
FIGURE 6. Theoretical model of atherosclerosis
and possible adverse health outcomes in firefighters.
© 2011 Lippincott Williams & Wilkins
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returning from an alarm, or involving vigorous physical training or
a strenuous rescue, are likely to be work-precipitated.
CONCLUSIONS
In conclusion, CVD remains the leading cause of line of duty
death among firefighters (45% of on-duty fatalities) and the prevalence of standard CVD risk factors remains high in this occupational
group. Over the last decade, however, our understanding of CVD
among firefighters has significantly improved with respect to the
following. First, the physiology of CV arousal and other changes
that occur in association with acute firefighting activities have been
well-characterized. Second, unique statistical approaches have documented that on-duty CVD events do not occur at random in the fire
service. They are more frequent at certain times of day, certain
periods of the year, and are overwhelmingly more frequent during
strenuous duties compared with nonemergency situations. Third,
clinical epidemiology investigations have proven, as expected, on-duty
CVD events occur almost exclusively among susceptible firefighters
with underlying CVD (whether overt and previously diagnosed or
theretofore, unrecognized and “subclinical”) (Fig. 6). Thus, it is imperative that preventive measures with proven benefits in the general
population be applied in a more aggressive manner to firefighters
who serve public safety, experience severe CV strain during emergency operations, and are exposed to increased risks of acute CVD
adverse events while performing emergency duties. Furthermore, all
fire departments should have entry-level medical evaluations, institute periodic medical evaluations, and define return to work evaluation procedures that require clearance by an experienced occupational physician after major or significant illness. On the basis of
overwhelming evidence supporting markedly higher relative risks
of on-duty death and disability among firefighters with a history of
CHD, most firefighters with known CHD or other clinically significant atherosclerotic endpoints should be restricted from participating in strenuous emergency duties.
ACKNOWLEDGMENTS
The authors would like to thank Leonard Lilly, MD, very
much for his critical review of the manuscript and excellent suggestions.
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